Three-dimensional gadolinium-enhanced dynamic MRI of whole liver using spectrally selected enhanced fast gradient recall sequence]

Although scribing has been used in ophthalmology for many years, the real benefits could not be realized until the entry of managed care into medicine in the United States. Everyone benefits in an office that uses scribes. The patient and the physician benefit by having a record that is much closer to being complete. The technician benefits as a result of becoming a pivotal reference for every patient encounter.     

MRI of fibrous cortical defect of the femur

Concurrent with the new technologies in oral disease prevention, diagnosis, and treatment are the changing global perspectives on health which impact significantly on who will actually receive the new technologies and services. Issues of access to care, the rapidly changing social, political, and economic environments and the growing recognition of the disparities and barriers to oral health are stimulating new strategies for positive change and enhancement. Governments, in partnership with professional associations, private sector concerns and consumer interests in Canada and the United States, have recently reviewed current oral health status and identified needs and inequities. A few bold new multisectoral initiatives have evolved but not enough to address all the trends. The challenges not adequately addressed by current policies and practices have been identified. Goals for oral health have been established both nationally and internationally to address the trends and the challenges. Critical areas for taking action have been also been identified and include research in epidemiology, behavioural and social sciences, health services, and evaluation. This type of research considers the social and environmental context of where and how oral services are provided. Ultimately this is the kind of research that can radically change the role of the dental hygienist in the delivery of oral health care.     

Mechanical and biological properties of two types of bioactive bone cements containing MgO-CaO-SiO2-P2O5-CaF2 glass and glass-ceramic powder

The electrostatic steering of charged ligands toward the active site of Torpedo californica acetylcholinesterase is investigated by Brownian dynamics simulations of wild type enzyme and several mutated forms, in which some normally charged residues are neutralized. The simulations reveal that the total ligand influx through a surface of 42 A radius centered in the enzyme monomer and separated from the protein surface by 1-14 A is not significantly influenced by electrostatic interactions. Electrostatic effects are visible for encounters with a surface of 32 A radius, which is partially hidden inside the protein, but mostly within the solvent. A clear accumulation of encounter events for that sphere is observed in the area directly above the entrance to the active site gorge. In this area, the encounter events are increased by 40% compared to the case of a neutral ligand. However, the differences among the encounter rates for the various mutants considered here are not pronounced, all rate constants being within +/- 10% of the average value. The enzyme charge distribution becomes more important as the charged ligand moves toward the bottom of the gorge, where the active site is located. We show that neither the enzyme's total charge, nor its dipole moment, fully account for the electrostatic steering of ligand to the active site. Higher moments of the enzyme's charge distribution are also important. However, for a series of mutations for which the direction of the enzyme dipole moment is constant within a few degrees, one observes a gradual decrease in the diffusional encounter rate constant with the number of neutralized residues. On the other hand, for other mutants that change the direction of the dipole moment from that of the wild type, the calculated encounter rate constants can be very close to that of the wild type. The present work yields two new insights to the kinetics of acetylcholinesterase. First, evolution appears to have built a redundant electrostatic steering capability into this important enzyme through the overall distribution of its thousands of partially charged atoms. And second, roughly half of the rate enhancement due to electrostatics arises from steering of the substrate outside the enzyme; the other half of the rate enhancement arises from improved trapping of the substrate after it has entered the gorge. The computational results reproduce qualitatively, and help to rationalize, many surprising experimental results obtained recently for human acetylcholinesterase.     

The role of 36 megadalton plasmid of Salmonella enteritidis for the pathogenesis in mice

The pathogenesis associated with the 36 Megadalton (Md) plasmid of Salmonella choleraesuis subsp. choleraesuis serovar Enteritidis (S. Enteritidis) was assessed by using the plasmid-containing strain AL1190, plasmid-cured strain AL1192, and plasmid-reintroduced strain AL1193. After oral inoculation of strain AL1190 or AL1192 to C57BL/6 mice, mesenteric lymph nodes, spleens, and livers were examined for the numbers of viable bacteria and for the histopathological changes. The numbers of bacteria were greater and histopathological changes were severer in these organs of mice inoculated with strain AL1190, than in those with strain AL1192. Strains AL1190, AL1192, and AL1193 showed the equivalent survival rate to sera of guinea pig, calf, and pig, and grew equally well under the iron-limiting conditions. These results suggested that the 36 Md plasmid of S. Enteritidis contribute to the spread of the infection beyond small intestines to mesenteric lymph nodes, spleens, and livers, but not to serum resistance or acquisition of iron.     

Production of basic fetoprotein in human peripheral lymphocytes during blastic transformation

To clarify the significance of basic fetoprotein (BFP) in lymphocytes, we investigated whether BFP is produced in lymphocytes during blastic transformation. Peripheral blood lymphocytes obtained from 14 adults were cultured under the stimulation of lectins. The concentration of BFP in the culture medium (extracellular BFP) was estimated serially. The incorporation of [6-3H]-thymidine was assayed simultaneously. The intracellular BFP was measured by dual flow cytometry for DNA and BFP. A lymph node was studied immunohistochemically. Serum BFP was measured in four cases of lymphocytic leukaemia. In two cases, dual staining was performed. The intracellular BFP of the mitogen-stimulated lymphocytes was increased within 24 h. The extracellular BFP was increased exponentially from 72 h. The extracellular BFP at 96 h did not correlate with the [3H]-thymidine incorporation. The intracellular BFP increase began in G1 phase. Immunostaining showed that the B cells also produced BFP. The serum BFP level in leukaemia was high in 1 of 4 cases and the leukaemic cells in two cases showed high intracellular BFP content. These observations indicate that BFP is produced in activated human lymphocytes and in lymphocytic leukaemic cells. The production of BFP during blastic transformation will be a useful new in vitro model for studying the biological role of BFP, and BFP labelling may offer some new possibilities for the study of lymphocytes.     

Adult onset of the Dandy-Walker syndrome

OBJECTIVE: We describe the CT findings of medial transfer of a sartorius muscle flap, which is done to protect the femoral blood vessels after radical inguinal lymphadenectomy for cancer or surgical debridement of infected femoral vascular grafts. MATERIALS AND METHODS: We reviewed the appearances and initial interpretations of 33 CT studies in 17 patients who underwent medial sartorius flap transfer after either (1) inguinal lymphadenectomy for melanoma or penile cancer or (2) debridement of infected groin wounds complicating vascular reconstruction of the femoral arteries. Muscle flap transfer was defined by the surgical record as either complete or incomplete. In complete sartorius muscle transfer, the proximal end of the muscle is dissected from the anterior superior iliac spine, rotated along its long axis, and sutured medially to the inguinal ligament. In incomplete transfer, the muscle it mobilized and stretched medially, and its medial border is fixed to the inguinal ligament and deep tissues. Clinical correlation and follow-up examinations were done for all patients, and CT reevaluation at intervals was done in nine patients. RESULTS: Complete sartorius flap transfer resulted in a mass anterolateral or anterior to the femoral vessels on postoperative CT scans in 20 studies; five of these masses were misinterpreted initially as possible recurrent metastatic lymphadenopathy, infection, or hematoma. Incomplete sartorius flap transfer resulted in bandlike stretching of the muscle over the femoral vessels in 13 studies. CONCLUSION: Medial transfer of the sartorius muscle causes a variable appearance of the groin on CT scans. The findings on CT scans after complete sartorius flap transfer should be distinguished from recurrent lymphadenopathy and from postoperative phlegmon or hematoma.     

An estimation of load characteristics of an ultrasonic motor by measuring transient responses

To measure the characteristics of ultrasonic motors, such as the maximum torque, torque-speed relationship and the frictional coefficient at the contact surface, a method in which the torque is calculated from the transient responses is proposed. The rise curve that is the transitional change in the rotor speed soon after turning on the motor gives the load characteristics, while the fall curve that is the decay of the rotor speed after turning off the motor yields the frictional coefficient of the contact surface. This method requires only a short time (the transient time of the motor) to complete the measurement. The relations between the transient responses, the load characteristics and the frictional force are analyzed, and the method is applied to a hybrid transducer type rotary motor and a traveling wave type linear motor.     

An ultrasonic motor using bending vibrations of a short cylinder

An ultrasonic motor using bending vibrations of a short cylinder with free-free ends is proposed, and its performance and efficiency are discussed. The motor is small in size and realizes a high mechanical output of more than 1 W. The general principle of the motor, which uses traveling waves, is as follows. When a traveling wave propagates along an elastic object, particles at the surface move elliptically. A movable object (a slider or a rotor) pressed to the elastic object may be caused to move due to the frictional forces between it and the surface. A motor based on this principal has been constructed and studied. The vibration mode used is found to have an undesirable radial component, which restricts the efficiency of the motor to about 10% at best. A large amount of the energy supplied is lost by the slippage owing to the existence of the undesirable component. It is concluded that to derive larger output power, the frictional material needs to be carefully chosen.     

Evidence that Crystal Facet Orientation Dictates Oxygen Evolution Intermediates on Rutile Manganese Oxide

Elucidating the mechanism that differentiates the oxygen‐evolving center of photosystem II with its inorganic counterpart is crucial to develop efficient catalysts for the oxygen evolution reaction (OER). Previous studies have suggested that the larger overpotential for MnO₂ catalysts under neutral conditions may result from the instability of the Mn³⁺ intermediate to charge disproportionation. Here, by monitoring the surface intermediates of electrochemical OER on rutile MnO₂ with different facet orientations, a correlation between the stability of the intermediate species and crystal facets is confirmed explicitly for the first time. The coverage of the Mn³⁺ intermediate is found to be 11‐fold higher on the metastable (101) surfaces compared to (110) surfaces, leading to the superior OER activity of (101) surfaces. The difference in OER activity may result from the difference in surface electronic states of Mn³⁺, where interlayer charge comproportionation of Mn²⁺ and Mn⁴⁺ to generate two Mn³⁺ species is favored on (101) facets. Considering the fact that the OER enzyme accommodates Mn³⁺ stably during the Kok cycle, the enhanced OER activity of the rutile MnO₂ catalyst with a metastable surface highlights the importance of mimicking not only the crystal structure but also the electronic structure of the targeted natural enzyme.     

An ultrashort-duration, high-repetition-rate pulse source for laser ionization/mass spectrometry

This paper describes a sample inlet system with several advantages over other pulsed valves, as applied to resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry. The nozzle is based on online concentration by analyte adsorption/laser desorption (online COLD), where a capillary column with a narrowly synthesized tip is employed for sample introduction. The analyte molecules adsorbed at the tip are desorbed by a pulsed laser and are injected into a mass spectrometer as a packet. The online COLD nozzle can produce very short gas pulses on the order of 1 μs. Moreover, this nozzle is capable of operating over a wide range of repetition rates from 1 Hz to 1 kHz. In addition, this nozzle intrinsically possesses several unique characteristics; for instance, it can be heated to very high temperatures and has nearly zero dead volume. Therefore, the present sample introduction technique offers an ideal and versatile nozzle for laser ionization/mass spectrometry.