A neutral triangular supramolecule formed by Mo2(4+) units.
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Journal Article↗
Biomedical subjects
C Lin
Publications and source records attributed to C Lin.
Connecting pairs of dimetal units to form molecular loops.
Four compounds consisting of molecular loops formed from two quadruply bonded Mo2(DAniF)2 (DAniF = N,N'-di-p-anisylformamidinate) units linked by two dicarboxylate anions have been prepared in high purity and essentially quantitative yields. These compounds have been characterized by crystallography and NMR spectroscopy and display electrochemical behavior dependent on the nature of the dicarboxylate anion. However, the electronic communication between the two Mo2(4+) units is not strong. As denoted by the dicarboxylate linkers, the compounds are malonate, 1, 1,4-phenylendiacetate, 2, homophthalate, 3, and trans-cyclopentane-1,2-dicarboxylate, 4.
Journal Article↗
Supramolecular squares with Mo2(4+) corners.
Seven complexes obtained by reacting the quadruply bonded complex [Mo2(cis-DAniF)2(CH3CN)4](BF4)2 (DAniF = N,N'-di-p-anisylformamidinate) and (Bun4N+)2(Carb2-), where Carb2- is a dicarboxylate anion, have been found to have a ratio of dimetal unit to dicarboxylate of 1:1. As noted by the carboxylate linker, the compounds are oxalate, 1, fumarate, 2, ferrocene dicarboxylate, 3, 4,4'-biphenyldicarboxylate, 4, acetylenedicarboxylate, 5, tetrafluorophthalate, 6, and carborane dicarboxylate, 7. Structural characterization of 1-4 revealed a square of dimolybdenum units linked by the dicarboxylate anions, each having an interstice capable of accommodating specific solvent molecules. Results of NMR studies of all seven compounds are consistent with the presence of a highly symmetrical structure. These compounds display a rich electrochemical behavior that is affected by the nature of the carboxylate group.
Journal Article↗
SUB1, an Arabidopsis Ca2+-binding protein involved in cryptochrome and phytochrome coaction.
Cryptochromes and phytochromes are the major photosensory receptors in plants and often regulate similar photomorphogenic responses. The molecular mechanisms underlying functional interactions of cryptochromes and phytochromes remain largely unclear. We have identified an Arabidopsis photomorphogenic mutant, sub1, which exhibits hypersensitive responses to blue light and far-red light. Genetic analyses indicate that SUB1 functions as a component of a cryptochrome signaling pathway and as a modulator of a phytochrome signaling pathway. The SUB1 gene encodes a Ca2+-binding protein that suppresses light-dependent accumulation of the transcription factor HY5.
Amino Acid Motifs↗
High-resolution intracranial and cervical MRA at 3.0T: technical considerations and initial experience.
Initial experience with intracranial and cervical MRA at 3.0T is reported. Phantom measurements (corrected for relaxation effects) show S/N (3.0T) = 2.14 +/- 0.08 x S/N (1.5T) in identical-geometry head coils. A 3.0T 3DTOF intracranial imaging protocol with higher-order autoshimming was developed and compared to 1.5T 3DTOF in 12 patients with aneurysms. A comparison by two radiologists showed the 3.0T to be significantly better (P < 0.001) for visualization of the aneurysms. The feasibility of cervical and intracranial contrast enhanced MR angiography (CEMRA) at 3.0T is also examined. The relaxivity of the gadolinium contrast agent decreases by only about 4-7% when the field strength is increased from 1.5 to 3.0T. Cervical 3.0T CEMRA was obtained in eight patients, two of whom had 1.5T studies available for direct comparison. Image comparison suggests 3.0T to be a favorable field strength for cervical CEMRA. Voxel volumes of 0.62-0.73 mm(3) (not including zero-filling) were readily achieved at 3.0T with the use of a single-channel transmit-receive head or cervical coil, a 25 mL bolus of gadoteridol, and a 3D pulse sequence with a 66% sampling efficiency. This spatial resolution allowed visualization of intracranial aneurysms, carotid dissections, and atherosclerotic disease including ulcerations. Potential drawbacks of 3.0T MRA are increased SAR and T(*)(2) dephasing compared to 1.5T. Image comparison suggests signal loss due to T(*)(2) dephasing will not be substantially more problematic than at 1.5T. The dependence of RF power deposition on TR for CEMRA is calculated and discussed.
Brain↗
A comparative study of the effects of magnetic stimulation and electric stimulation on peripheral nerve injury in rat.
The influence of pulsed magnetic stimulation (MS) on the sciatic nerve injury was investigated. Thirty rats were divided into three groups equally: MS group (A), electric stimulation (ES) group (B) and the control group (C). The MS and ES were applied immediately after the first 10 min of the sciatic nerve crush. Sciatic function index (SFI), toe spreading reflex (TSR), muscular weight and volume were measured after the experiment. The TSR of in the groups A and B occurred at 4th day while in the control group it occurs at 10th day. There was statistically significant difference in SFI between groups A and B (P < 0.01). The weight and volume of the gastrocnemius muscle were statistically greater in the groups A and B than in the control group (P < 0.01). The effect of MS was similar to that of ES. It was suggested that the application of MS immediately after the nerve injury might have an important clinical value as it can accelerate functional recovery and prevent or minimize muscle atrophy. The technique is easily to operate, non-invasion, painless and permits tolerance of high intensity output to be used.
Animals↗
Cultures of equine respiratory epithelial cells and organ explants as tools for the study of equine influenza virus infection.
Equine nasal turbinate epithelial cells and tracheal rafts were maintained with sustained viability in culture. Both types of culture supported productive replication of equine influenza virus (equine-2, subtype H3N8) and cell death occurred through apoptosis following viral infection. Thus, primary respiratory epithelial cell and organ cultures of equine origin may be valuable as alternatives to the intact animal for studying the virus-host interaction of equine respiratory viruses including influenza.
Animals↗
Transport modeling of copper and cadmium with linear and nonlinear retardation factors.
The predictive accuracy of using the one-dimensional advection-dispersion equation to evaluate the fate and transport of solute in a soil column is usually dependent on the proper determination of chemical retardation factors. Typically, the distribution coefficient (Kd) obtained by fitting the linear sorption isotherm has been extensively used to consider general geochemical reactions on solute transport in a low-concentration range. However, the linear distribution coefficient cannot be adequately utilized to describe the solute fate at a higher concentration level. This study employed the nonlinear equilibrium-controlled sorption parameters to determine the retardation factor used in column leaching experiments. Copper and cadmium transportation in a lateritic silty-clay soil column was examined. Through the explicit finite-difference calculations with a third-order total-variation-diminishing (TVD) numerical solution scheme, all results of the theoretical copper and cadmium breakthrough curves (BTCs) simulated by using the Freundlich nonlinear retardation factors revealed good agreement with the experimental observations.
Adsorption↗
Effect of slip on movement of body center of mass relative to base of support.
OBJECTIVE: The purpose is to investigate the effect of balance conditions and slippery perturbation on the position and velocity of the body's center of mass relative to the body's base of support. DESIGN: Twenty-two young and healthful subjects were investigated while their walk was perturbed by a soap patch applied over a force plate. A safety harness was used to prevent the subject from falling on knee or buttock. BACKGROUND: Appropriate postural response to meet physiological biomechanical requirements is mandatory in restoration of balance upon slip. METHODS: Twenty-two healthy subjects dressed with safety harness walked first without and then with slippery perturbation, guided by a metronome at 120 steps/min and 90 steps/min cadence. Data were collected from a motion analysis system and force plates. RESULTS: For slippery perturbation, the displacement and velocity of center of mass with respect to base of support became smaller from heel strike to contralateral toe off. Subject's balance condition correlated significantly to the displacement of center of mass with respect to base of support (r=-0.51 at 120 steps/min and r=-0.471 at 90 steps/min), as well as the velocity (r=-0.834 at 120 steps/min, r=-0.673 at 90 steps/min) at contralateral toe off. CONCLUSIONS: For slip during walking, smaller excursion and faster velocity of center of mass with respect to base of support were important for subjects regaining balance from heel strike to contralateral toe off. The critical time for subjects regaining stability is the first double support phase of the gait cycle. RELEVANCE: It is confirmed that two variables, the displacement and the velocity of center of mass with respect to base of support, are valuable biomechanical factors and provide quantifiable determination for investigation of the balance condition in slipping.
Accidental Falls↗
Risk for respiratory distress syndrome in preterm infants born to mothers complicated by placenta previa.
This study examined the risk factors for respiratory distress syndrome (RDS) in preterm infants from pregnancies complicated by placenta previa. Forty preterm infants born to mothers with placenta previa between January 1989 and December 1995 in a medical center were enrolled. Each of these patients was matched in gestational age and gender with an infant born immediately after to a mother without placenta previa. Obstetric and neonatal outcome variables were collected. The mean+/-S.D. gestational age for both groups was 33.0+/-3.1 weeks. There was no difference in mean birthweight between the placenta previa and control groups (2129+/-598 vs. 2136+/-493 g). All the patients in the former and 11 (28%) in the latter were born by cesarean section. About a half of the mothers in both groups received antenatal steroids. Infants from placenta previa pregnancies had a higher incidence (21/40 vs. 10/40, P<0.01) and more severe RDS than controls. Stratified by the status of treatment with antenatal steroid, we found that gestational age was a significant risk factor for RDS in both treated and untreated groups (P<0.01), but placenta previa was an independent risk factor (odds ratio 32; CI 1-4182) by multiple exact logistic regression in antenatal steroid-treated group. We conclude that preterm infants born to mothers with placenta previa had a higher risk for RDS than controls. It played an independent role, in addition to gestational age, only in infants treated with antenatal steroid. We speculate that placenta previa was not directly contributing to RDS, but through other associated risk factors for RDS.
Adrenal Cortex Hormones↗
Cardioprotective effects of ATP-sensitive potassium channel opener (cromakalim) in surgically induced cardiac arrest.
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Journal Article↗
Supramolecular arrays based on dimetal building units.
Supramolecular chemistry is today a major thrust area, a significant part of which is based on the use of metal atoms or ions as key elements in promoting the assembly of and dictating the main structural features of the supramolecular products. Most of the work has been done with single metal atoms or ions in this role, but considerable success has already been achieved by employing M-M bonded dimetal entities instead. We review here the work done in our laboratory. Metal-metal bonded cationic complexes of the [M(2)(DAniF)(n)(MeCN)(8-2n)]((4-n)+) type, where M = Mo or Rh and DAniF is an N,N'-di-p-anisylformamidinate anion, have been used as subunit precursors and then linked by various equatorial and axial bridging groups such as polycarboxylate anions, polypyridyls, and polynitriles. Characterization of the products by single-crystal X-ray diffraction, CV, DPV, NMR, and other spectroscopic techniques has revealed the presence of discrete tetranuclear (pairs or loops), hexanuclear (triangles), octanuclear (squares), and dodecanuclear (cages) species and one-, two-, or three-dimensional molecular nanotubes. These compounds display a rich electrochemical behavior which is affected by the nature of the linkers.
Journal Article↗
TGF-beta1 promotes microglial amyloid-beta clearance and reduces plaque burden in transgenic mice.
Abnormal accumulation of the amyloid-beta peptide (Abeta) in the brain appears crucial to pathogenesis in all forms of Alzheimer disease (AD), but the underlying mechanisms in the sporadic forms of AD remain unknown. Transforming growth factor beta1 (TGF-beta1), a key regulator of the brain's responses to injury and inflammation, has been implicated in Abeta deposition in vivo. Here we demonstrate that a modest increase in astroglial TGF-beta1 production in aged transgenic mice expressing the human beta-amyloid precursor protein (hAPP) results in a three-fold reduction in the number of parenchymal amyloid plaques, a 50% reduction in the overall Abeta load in the hippocampus and neocortex, and a decrease in the number of dystrophic neurites. In mice expressing hAPP and TGF-beta1, Abeta accumulated substantially in cerebral blood vessels, but not in parenchymal plaques. In human cases of AD, Abeta immunoreactivity associated with parenchymal plaques was inversely correlated with Abeta in blood vessels and cortical TGF-beta1 mRNA levels. The reduction of parenchymal plaques in hAPP/TGF-beta1 mice was associated with a strong activation of microglia and an increase in inflammatory mediators. Recombinant TGF-beta1 stimulated Abeta clearance in microglial cell cultures. These results demonstrate that TGF-beta1 is an important modifier of amyloid deposition in vivo and indicate that TGF-beta1 might promote microglial processes that inhibit the accumulation of Abeta in the brain parenchyma.
Aged↗
Molecular therapy with recombinant antisense c-myc adenovirus for human gastric carcinoma cells in vitro and in vivo.
BACKGROUND AND AIMS: This study used a recombinant antisense c-myc adenovirus (Ad-ASc-myc) to evaluate how alterations of c-myc expression in the SGC7901 human gastric carcinoma cells could influence the proliferation, apoptosis and the growth of human gastric tumors in nude mice. METHODS: The human gastric carcinoma cell line, SGC7901, treated with Ad-ASc-myc or adenovirus recombinants carrying LacZ gene (Ad-LacZ) were analyzed by using X-gal stain, MTT, DNA ladder, TUNEL assay, flow cytometric analysis, polymerase chain reaction and western blot in vitro. The tumorigenicity and experimental therapy in nude mice models were assessed in vivo. RESULTS: The Ad-ASc-myc could strongly inhibit cell growth and induce apoptosis in SGC7901 cells. The proliferation of the Ad-ASc-myc-infected SGC7901 cells was reduced by 44.1%. The mechanism of killing gastric carcinoma cells by Ad-ASc-myc was found to be apoptosis, which was detected by the use of a DNA ladder, TUNEL and flow cytometric analysis. Infection of Ad-ASc-myc in nude mice showed that all three mice failed to form tumors from the 7 to 30 day period, compared with injection of Ad-LacZ and parent SGC7901 cells. Experimental therapy on the nude mice bearing subcutaneous tumors of SGC7901 cells showed that intratumor instillation of Ad-ASc-myc inhibited the growth of the tumors. Recombinant antisense c-myc adenovirus-treated tumors were inhibited by 68.9%, compared with tumors injected with Ad-LacZ and control (LacZ and phosphate-buffered saline). CONCLUSION: The expression of Ad-ASc-myc can inhibit growth and induce apoptosis of gastric cancer cells in vitro and in vivo and thus is a potential clinical utility in gene therapy for the treatment of gastric carcinoma.
Adenoviridae↗
Could capillary zone electrophoresis of tryptic peptides be used for the characterization of hemoglobin variants?
The present article describes a simple and rapid new peptide mapping procedure that could be used to assist identification of rare hemoglobin variants in clinical laboratories. Four hemoglobin variants were taken as example, namely Hb D-Ouled Rabah, Hb Marseille, Hb G-Philadelphia, and Hb Ube-2, and isolated by electrophoresis at alkaline pH. The globin chains were aminoethylated and, after tryptic digestion, the peptides were separated by a capillary zone electrophoresis method. Highly reproducible migration times of the peptides were obtained with intra-assay and inter-assay coefficients of variation of less than 1 and 2%, respectively.
Amino Acid Sequence↗
The collagen receptor DDR2 regulates proliferation and its elimination leads to dwarfism.
The discoidin domain receptor 2 (DDR2) is a member of a subfamily of receptor tyrosine kinases whose ligands are fibrillar collagens, and is widely expressed in postnatal tissues. We have generated DDR2-deficient mice to establish the in vivo functions of this receptor, which have remained obscure. These mice exhibit dwarfism and shortening of long bones. This phenotype appears to be caused by reduced chondrocyte proliferation, rather than aberrant differentiation or function. In a skin wound healing model, DDR2-/- mice exhibit a reduced proliferative response compared with wild-type littermates. In vitro, fibroblasts derived from DDR2-/- mutants proliferate more slowly than wild-type fibroblasts, a defect that is rescued by introduction of wild-type but not kinase-dead DDR2 receptor. Together our results suggest that DDR2 acts as an extracellular matrix sensor to modulate cell proliferation.
Animals↗
Magnetic resonance angiography at 3.0 Tesla: initial clinical experience.
Magnetic resonance (MR) angiography has undergone significant development over the past decade. It has gone from being a novelty application of MR with limited clinical use to replacing catheter angiography in some clinical applications. One of the principal limitations inherent to all MR angiographic techniques is that they remain signal limited when pushed to the limits of higher resolution and short acquisition time. Developments in magnetic gradient hardware, coil design, and pulse sequences now are well optimized for MR angiography obtained at 1.5-T main magnetic field (B-field) strength, with acquisition times and imaging matrix size near their optimal limits, respectively. Recently, the United States Food and Drug Administration (FDA) approved use of clinical magnetic resonance imaging with main magnetic field strengths of up to 4 T. Before FDA approval, use of MR with magnetic field strengths much greater than 1.5 T was essentially reserved for investigational or research applications. The main advantage of high B-field imaging is a significant improvement in the signal-to-noise ratio (SNR), which increases in an approximately linear fashion with field strength in the range of 1.5 to 3.0 T. This increased SNR is directly available when performing MR angiographic acquisitions at higher magnetic field strengths, allowing for better resolution and conspicuity of vessels with similar acquisition times. Little has been reported on the benefits of performing MR angiography at magnetic field strengths >1.5 T. The purpose of this article is to summarize our current experience with intracranial and cervical MR angiographic techniques at 3.0 T.
Equipment Design↗
Necrotizing fasciitis of the head and neck: an analysis of 47 cases.
Necrotizing fasciitis is an overwhelming infection common to the perineum, abdominal wall, and extremities. It is a surgical emergency related to a high mortality rate that is more often seen in elderly and immunocompromised patients. Necrotizing fasciitis occurs uncommonly in the head and neck region. Over a 12-year period, 47 cases of necrotizing fasciitis of the head and neck region were collected at this hospital. The demographics, predisposing factors, clinical presentation and courses, management, complications, and outcomes were analyzed. The cases were divided into two groups: survivors and nonsurvivors. Statistical comparisons were made of the parameters age, gender, smoking or drinking habit, underlying medical problems, laboratory data, and treatments used. Forty-two patients (89.4 percent) had associated systemic disease; most of these patients had diabetes (72.3 percent). The clinical manifestations are nonspecific but are often typical for diagnosis. The necessity of computed tomographic scans is not conclusive in this study. Presentation of septic shock (p = 0.004) and association with underlying malignancy (p = 0.03) were the only statistically significant factors that led to a poor prognosis. The cornerstones of proper management include early diagnosis, aggressive surgical debridement, broad-spectrum antibiotics, and intensive supportive care.
Adolescent↗