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PubMed2002

Strain rate imaging: an in vitro "validation" study using a physiologic balloon model mimicking the left ventricle.

BACKGROUND: Strain rate imaging (SRI) can be implemented from digital ultrasound loops of tissue Doppler imaging (TDI) data and is performed as an autocorrelation solution of the distance between intramyocardial targets. As such, it should have better resolution along longer distances of wall segments that are imaged at the length of individual ultrasound scan lines. METHODS: We used a new left ventricular double-balloon phantom with a tissue-mimicking gel between the walls. Mounted in a water bath and connected to a pulsatile flow pump at four-stroke volume (30-50 ml/beat), the high frame rate, digital, multiple two-dimensional/tissue/TDI loops of balloon wall motion were recorded using a GE VingMed system FiVe (3.5 MHz phased array transducer), with the model scanned longitudinally from the apex. The strain rate (SR) values were measured at the apex and the lateral wall using an offline measurement program, and mean SR values for every 100 msec were calculated by averaging three determinations at each point. The excursions of the apex and lateral wall also were measured directly by high speed digital video imaging, and consecutive velocity profiles were calculated every 100 msec. A total of 40 data points for four-stroke volumes were analyzed. RESULTS: While our balloon model had enough gel targets between the walls to produce a good mimic of myocardial speckle with walls that thickened and thinned, samples immediately across the apex and apex SR values (Hz) varied substantially. In contrast, systematic signals could be obtained from lines imaged >15 degrees from the true apex and crossing a longer length of myocardium. At the lateral wall, there was a close correlation between the video velocities and SR values, as well as a close overlap of the phasic patterns. CONCLUSIONS: SRI produces more reliable data from wall segments parallel to scan lines.

Blood Flow Velocity↗
PubMed2004

E1-Ngn2/Cre is a new line for regional activation of Cre recombinase in the developing CNS.

We generated a transgenic mouse line named E1-Ngn2/Cre that expresses Cre recombinase and GFP under the control of the E1 enhancer element of the gene Ngn2 (Scardigli et al.: Neuron 31:203-217, 2001). Cre-recombinase activity and GFP fluorescence are consistent with the reported expression pattern controlled by the E1-Ngn2 enhancer. Recombination was detected in the progenitor domains p1 and p2 in the ventricular zone of the neural tube and in distinct domains of the pretectum, the dorsal and ventral thalamus, the tegmentum of the mesencephalon, and the hindbrain. In the developing cortex, Cre-recombinase activity is confined to a subpopulation of progenitors predominantly in the region of the ventral and lateral pallium. The E1-Ngn2/Cre mouse line thus provides an excellent novel tool for a region-specific conditional mutagenesis in the developing CNS.

Animals↗
PubMed2004

L-citrulline immunoreactivity reveals nitric oxide production in the electromotor and electrosensory systems of the weakly electric fish, Apteronotus leptorhynchus.

Weakly electric fish produce electric organ discharges (EODs) used for electrolocation and communication. In the brown ghost knifefish, Apteronotus leptorhynchus, several neuron types in brain regions that control the EOD or process electrosensory information express nitric oxide synthase (NOS). The present study used immunoreactivity for L-citrulline, a byproduct of the production of nitric oxide (NO) by NOS, to assess NO production in NOS-expressing neurons. A polyclonal antibody against L-citrulline produced specific labeling in most neuronal populations previously identified to express NOS. Specifically, several cell types that precisely encode temporal information and/or fire at high frequencies, including spherical cells in the electrosensory lateral line lobe, giant cells in layer VI of the dorsal torus semicircularis, and pacemaker and relay cells in the pacemaker nucleus, were strongly immunoreactive for L-citrulline. This suggests that these neurons produced high levels of NO. Notably, electromotor neurons, which also strongly express NOS, were not immunoreactive for L-citrulline, suggesting that NOS did not produce high levels of NO in these neurons. No apparent differences in L-citrulline distribution or intensity were observed between socially isolated fish and fish exposed to playback stimuli simulating the presence of a conspecific. This suggests that social stimulation by electrocommunication signals is not necessary for high levels of NO production in many NOS-positive neurons. Future studies focusing on regulation of NO production in these systems, and the effects of NO on electrosensory processing and electromotor pattern generation will help elucidate the function of NO signaling pathways in this system.

Animals↗
PubMed2002

Renal failure due to scleroderma with thrombotic microangiopathy developing in a woman treated with carboplatin for ovarian cancer.

Acute renal failure in association with microangiopathic hemolytic anemia and the pathological finding of thrombotic microangiopathy may occur in a number of conditions including hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and systemic sclerosis. Distinguishing between these conditions on clinical grounds may be difficult, and further investigations, including serological tests, are normally helpful. We present a patient who was treated with 5 doses of monthly carboplatin chemotherapy for stage IIb ovarian carcinoma and who subsequently developed acute renal failure and microangiopathic hemolysis together with some cutaneous features of systemic sclerosis. Initial serological tests, including anti-nuclear antibody titers measured using rat hepatocytes, were normal, and renal biopsy showed features of microangiopathic hemolysis, fibrinoid change, patchy tubular atrophy, and concentric intimal proliferation. A clinical diagnosis of diarrhea-negative hemolytic uremic syndrome was made and she was treated with plasma exchange and fresh frozen plasma infusion. However, she remained dialysis-dependent. Several weeks later she died following a cardiac arrest. Post-mortem examination revealed medial hypertrophy, concentric intimal proliferation, and thrombi within the small arteries of the kidneys and lungs. Subsequent results from tests taken at the time of her presentation with acute renal failure revealed a normal von Willebrand factor qualitative distribution, and a positive anti-nuclear antibody titer (using a human cell line) in association with positive autoantibodies to RNA polymerase types I, II, and III. Taken together, the clinical, laboratory, and post-mortem findings were suggestive of a diagnosis of systemic sclerosis. We discuss the differential diagnoses, and the associations between these and malignancy and chemotherapy. Finally, we consider the serological tests used for the diagnosis of systemic sclerosis that were, in this case, initially misleading.

Acute Kidney Injury↗
PubMed1989

Current trends in HMIS.

The firm of William F. Andrew & Associates, Inc., has been providing professional management consulting services to the healthcare field for more than 18 years. The firm specializes in Healthcare Management Information Systems (HMIS) and has assisted hospitals across the country in their respective HMIS procurements. In July 1988, the firm initiated a research project in which 140 vendors were invited to participate. The research methodology included a comprehensive Request-for-Information (RFI) with 2,225 line items addressing both application features/functions and corporate concerns. Initial analysis of the vendor responses indicates development of specific trends which will impact future HMIS procurements. In a series of articles, William F. Andrew summarizes the research conducted to date in the form of trends which have been confirmed and documented through telephone interviews with selected vendors. The detailed results of this research will be published at a later date.

Commerce↗
PubMed2002

Allopregnanolone attenuates N-methyl-D-aspartate-induced excitotoxicity and apoptosis in the human NT2 cell line in culture.

Progesterone modulates gamma-aminobutyric acid and excitatory amino acid neurotransmitter systems and has neuroprotective properties in models of hypoxia-ischemia. This study examined the in vitro effects of allopregnanolone, the active progesterone metabolite, in models of N-methyl-D-aspartate (NMDA)-induced necrosis and apoptosis. Cultured NT2 neurons were exposed to 1 mM NMDA. Lactate dehydrogenase (LDH) release was measured 24 h later. NMDA at a concentration of 1 mM produced a 39 +/- 19% release of total LDH. Exposure to 10 microM allopregnanolone prior to NMDA exposure reduced LDH release by 51% (P = 0.0028). NMDA stimulated apoptotic cell changes defined by terminal dUTP nick-end labeling (TUNEL) and 5,5', 6,6'-tetrachloro-1,1,3,3'-tetra ethlybenzimidazolycarbocyanide iodide staining were reduced to baseline values by both 10 microM allopregnanolone and 100 microM MK-801. Pretreatment with allopregnanolone (0-10 microM) reduced the percentage of TUNEL-positive cells in a dose-dependent manner (EC(50) = 2.7 +/- 0.1 nM). Physiologic concentrations of allopregnanolone provided protection against both necrotic and apoptotic injury induced by NMDA excitotoxicity.

Apoptosis↗
PubMed2006

Abutment rotational displacement of external hexagon implant system under lateral cyclic loading.

PURPOSE: This in vitro study investigated the effect of lateral cyclic loading with different load positions and periods on abutment rotational displacement (RD) of external hexagon implant system. MATERIALS AND METHODS: Four groups of five implant assemblies each were used. Each assembly consisted of Brånemark System Mk IV implant (Nobel Biocare AB, Göteborg, Sweden), CeraOne abutment (Nobel Biocare AB), and a cement-retained casting. A cyclic load of 50 N was applied centrally and perpendicular to the long axis of the implant for groups A and B for 0.25 and 0.50 x 10(6) cycles, respectively, while for groups C and D, the same load was applied at 4-mm distance eccentrically for 0.25 and 0.50 x 10(6) cycles, respectively. The displacement was evaluated by hand drawing a longitudinal line across the implant-abutment interface. Before and after loading, the lateral distance between two reference points on the abutment and implant was measured under high resolution (x200) and the difference formed the RD value. The data were analyzed with one-way analysis of variance and compared with Tukey test (alpha=0.05). RESULTS: Group D had the highest mean of RD value (55.00 +/- 1.871 microm), while group A had the lowest (2.800 +/- 0.837 microm). Groups A and B had a high statistically significant difference in RD values, as compared to groups C or D (p < .001). Moreover, group C had statistically significant difference from group D (p=.011). Conversely, no statistical significance was obtained when group A was compared with group B. CONCLUSION: Within the limits of this in vitro study, the RD of the external hexagon joint components occurred significantly under eccentric lateral loading when compared to centric loading. The displacement increased significantly with longer period of eccentric lateral loading.

Dental Abutments↗
PubMed1987

Production of human influenza virus in a stabile line of guinea pig tongue cells expressing endogenous oncovirus: an electron microscopic study.

Guinea pig tongue (GPT) cells represent a highly sensitive host system for influenza A/WSN (H1N1) infection as evidenced by numerous ultrastructural changes, considerable production of NS1 protein and widespread budding of viral particles at the cytoplasmic membrane. Vesicles of smooth endoplasmic reticulum and of the Golgi complex were transported to the apical area of cell membrane, where the budding of virions took place. Numerous microtubules were directed vertically to these portions of plasma membrane. In contrast, maturation of the endogenous oncovirus particles occurred at the lateral cytoplasmic membrane. Beneath the area of oncovirus maturation and release, a network was seen of microfilaments oriented towards the plasma membrane. The cytoplasm of GPT cells contained numerous nonstructural protein inclusions, which evidently accumulated at the periphery of nucleoli and were seen to reach the cytoplasm crossing the pores of nuclear membrane.

Animals↗
PubMed1998

Determination of halogenated hydrocarbons by helium microwave plasma torch time-of-flight mass spectrometry coupled to gas chromatography.

A helium microwave plasma torch (MPT) was coupled to time-of-flight mass spectrometry (TOFMS) for the detection of halogenated hydrocarbons separated by capillary gas chromatography (GC). The GC-MPT-TOFMS system offered excellent stability over the course of the experiments and avoided mass spectral peak distortions caused by spectral skew. In the initial studies, empirical formulas based on the halogen-to-carbon ratio were predicted utilizing a flow cell apparatus. The MPT proved to be very robust and could handle large amounts of organic vapor. Results from this study indicate that, for both aromatic and aliphatic halogenated hydrocarbons, the ratios of carbon to chlorine signals correlate well (r = 0.994) with the ones expected from their chemical composition. This study was later extended to include chromatographic separation. For a series of homologous aliphatic halogenated hydrocarbons, a correlation coefficient of 0.999 was obtained for both peak heights and peak areas obtained from a single chromatogram. A novel Nichrome wire-heated transfer line was developed to ensure that the capillary column was heated efficiently from the GC oven to the MPT and then through the length of the MPT up to the microwave plasma itself. No appreciable peak broadening and no detectable memory effects were associated with the heated transfer line. The GC-MPT-TOFMS system offered equal sensitivity for I, Br, and Cl. Absolute detection limits for the halogenated hydrocarbons ranged from 160 to 330 fg, constituting an improvement by a factor of 5-35 over earlier results obtained with MIPs supported in a TM010 cavity and combined with quadrupole-based mass spectrometry. In addition, the effect of molecular gases on the MPT performance was investigated. Up to about 1% (v/v) of either oxygen or hydrogen in the central channel helium flow attenuated the signal levels for both carbon and chlorine, with the larger loss seen in the chlorine signal.

Gas Chromatography-Mass Spectrometry↗
PubMed1989

Current trends in HMIS: Part II.

The firm of William F. Andrew & Associates, Inc., has been providing professional management consulting services to the healthcare field for more than 18 years. The firm specializes in Healthcare Management Information Systems (HMIS) and has assisted hospitals across the country in their respective HMIS procurements. In July 1988, the firm initiated a research project in which 140 vendors were invited to participate. The research methodology included a comprehensive Request-for-Information (RFI) with 2,225 line items addressing both application features/functions and corporate concerns. Initial analysis of the vendor responses indicates development of specific trends which will impact future HMIS procurements. In a series of articles, William F. Andrew summarizes the research conducted to date in the form of trends which have been confirmed and documented through telephone interviews with selected vendors. The detailed results of this research will be published at a later date.

Costs and Cost Analysis↗
PubMed2001

Deposition of the NG2 proteoglycan at nodes of Ranvier in the peripheral nervous system.

The node of Ranvier is a complex macromolecular assembly of ion channels and other proteins that is specialized for the rapid propagation of the action potential. A full understanding of the processes responsible for the assembly and maintenance of the node requires first the identification and characterization of the proteins found there. Here we show that NG2, a structurally unique chondroitin sulfate proteoglycan, is a molecular component of the node of Ranvier in the peripheral nervous system. In adult sciatic nerve, NG2 is (1) associated with thin, elongated fibroblast-like cells, (2) on some but not all basal laminae, and (3) at nodes of Ranvier. At the nodes, NG2 is restricted to the nodal gap and is absent from the paranodal or juxtaparanodal region. In dissociated cell cultures of adult sciatic nerve, perineurial fibroblasts but not Schwann cells express NG2 on their surfaces. Approximately 45% of the total NG2 in peripheral nerves is in a soluble, rather than particulate, subcellular compartment. NG2 is also present in membrane fractions that also contain high levels of voltage-dependent sodium channels, caspr, and neuron-glia related cell adhesion molecule. These medium-density membranes likely correspond to the nodal and paranodal region of the axon-Schwann cell unit. These results suggest a model in which perineurial fibroblasts secrete or shed NG2, which subsequently associates with nodes of Ranvier. The growth-inhibitory and anti-adhesive properties of NG2 may limit the lateral extension of myelinating Schwann cells as nodes mature. NG2 may also participate in the barrier functions of the perineurial linings of the nerve.

Animals↗
PubMed2004

Chemokine signaling regulates sensory cell migration in zebrafish.

Chemokines play an important role in the migration of a variety of cells during development. Recent investigations have begun to elucidate the importance of chemokine signaling within the developing nervous system. To better appreciate the neural function of chemokines in vivo, the role of signaling by SDF-1 through its CXCR4 receptor was analyzed in zebrafish. The SDF-1-CXCR4 expression pattern suggested that SDF-1-CXCR4 signaling was important for guiding migration by sensory cells known as the migrating primordium of the posterior lateral line. Ubiquitous induction of the ligand in transgenic embryos, antisense knockdown of the ligand or receptor, and a genetic receptor mutation all disrupted migration by the primordium. Furthermore, in embryos in which endogenous SDF-1 was knocked down, the primordium migrated towards exogenous sources of SDF-1. These data demonstrate that SDF-1 signaling mediated via CXCR4 functions as a chemoattractant for the migrating primordium and that chemokine signaling is both necessary and sufficient for directing primordium migration.

Animals↗
PubMed1998

Endothelin receptors and angiotensin II receptors in tumor tissue.

In cancer chemotherapy, selective enhancement of drug delivery to tumor tissue is essentially important for increase of chemotherapeutic effects. An attenuated vasoconstrictive response to angiotensin II (Ang II) in tumors and a marked increase in tumor blood flow were observed compared with normal tissues during systemic hypertension induced by Ang II infusion. The phenomenon was absent when hypertension was provoked by endothelin-1 (ET-1). We assessed this response to characterize ET receptor and Ang II receptor density and affinity in normal and tumor tissues. The tumor cell line LY80 was transplanted to the skin in nude rats. Four weeks later the rats were sacrificed. [125I] ET-1 and [125I Sar1, Ile8]-Ang II were used to map the receptors for ET and Ang II in rat tissues using computerized in vitro autoradiography. A moderately high density of ET receptors, (ETB > ETA) was found in tumors. The Ang II receptors were markedly reduced in tumor tissues without changes in the affinity. These results suggest that the decrease in Ang II receptors but not ET receptors in tumors may explain the hemodynamic effect of Ang II-induced hypertension and ET-induced hypertension on tumor blood flow.

Angiotensin II↗
PubMed1996

A totally integrated simulation technique for three-field breast treatment using a CT simulator.

A method was devised to simulate patients with breast cancer in the actual treatment position utilizing a diagnostic CT spiral scanner, 3-D Image Workstation for virtual simulation, and a laser coordinate system to transfer planning parameters to the patient's skin. It was desired to produce non-divergent tangential beams through the lung as well as a matched line for tangential and supraclavicular fields. The patients were immobilized in an Alpha CradleTM cast. Radio-opaque markers were placed on the superior, inferior, medial, and lateral margins of the field so as to afford appropriate initial field set-up approximations. The patient was scanned. The data set was then transferred to the workstation where an isocenter was chosen. The patient was marked. Virtual simulation was then performed. This method employed a half beam technique for the posterior edge of the tangential fields. Table rotation and blocking of the superior margin of the tangential fields were used to produce a vertical edge to match a supraclavicular field. Using a beam's eye view the lateral tangent was matched to the medial exit. A digitally reconstructed radiograph was created to define the tangent fields and place the supraclavicular block. Our initial experience with 50 patients verifies that this is a reproducible and accurate technique. Time required for immobilization and tangential field simulation is approximately 30 minutes. Data is available for 3-D treatment planning or 2-D treatment planning on a reconstructed transverse slice angled to match the collimator angle through the patient. Using a CT simulator for simulation of breast cancer affords accuracy of at least equal magnitude to conventional simulators as determined by beam films and ease of set-up. This technique also affords greater ease in changing treatment parameters without having to resimulate the patient.

Breast Neoplasms↗
PubMed1985

A genetic test for expression of a functional herpes simplex virus DNA-binding protein from a transfected plasmid.

The major DNA-binding protein, ICP8, encoded by herpes simplex virus is localized to the infected cell nucleus where it plays a role in viral DNA replication and control of viral gene expression. To identify the parts of the ICP8 protein that are important for its localization and functions, we have developed a system to test the ability of recombinant plasmids to express functional ICP8. A recombinant plasmid containing the wild-type ICP8 gene was transfected into cells. The cells were later infected with a temperature-sensitive ICP8 mutant virus at the nonpermissive temperature. Sufficient wild-type ICP8 was expressed from the transfected plasmid to complement the replication of the mutant virus. This provides a genetic system to test the properties of ICP8 expressed from mutagenized plasmids without the establishment of a stable cell line or the reintroduction of the ICP8 gene into the herpes simplex virus genome.

DNA Replication↗
PubMed1987

Acute effects of thoracic irradiation on lung function and structure in awake sheep.

To investigate the acute physiological and structural changes after lung irradiation, the effects of whole-lung irradiation were investigated in fourteen sheep. Ten sheep were prepared with vascular and chronic lung lymph catheters, then a week later were given 1,500 rad whole-lung radiation and monitored for 2 days. Four sheep were given the same dose of radiation and were killed 4 h later for structural studies. Lung lymph flow increased at 3 h after radiation (14.6 +/- 2.1 ml/h) to twice the base-line flow rate (7.5 +/- 1.3), with a high lymph-to-plasma protein concentration. Pulmonary arterial pressure increased twofold from base line (18 +/- 1.6 cmH2O) at 2 h after radiation (33 +/- 3.8). Cardiac output and systemic pressure in the aorta did not change after lung radiation. Arterial O2 tension decreased from 85 +/- 3 to 59 +/- 4 Torr at 1 day after radiation. Lymphocyte counts in both blood and lung lymph decreased to a nadir by 4 h and remained low. Thromboxane B2 concentration in lung lymph increased from base line (0.07 +/- 0.03 ng/ml) to peak at 3 h after radiation (8.2 +/- 3.7 ng/ml). The structural studies showed numerous damaged lymphocytes in the peripheral lung and bronchial associated lymphoid tissue. Quantitative analysis of the number of granulocytes in peripheral lung showed no significant change (base line 6.2 +/- 0.8 granulocytes/100 alveoli, 4 h = 10.3 +/- 2.3). The most striking change involved lung airways. The epithelial lining of the majority of airways from intrapulmonary bronchus to respiratory bronchiolus revealed damage with the appearance of intracellular and intercellular cell fragments and granules. This new large animal model of acute radiation lung injury can be used to monitor physiological, biochemical, and morphological changes after lung radiation. It is relevant to the investigation of diffuse oxidant lung injury as well as to radiobiology per se.

Animals↗
PubMed1995

Technical note: computed tomography imaging with a radiotherapy simulator.

An inexpensive system for obtaining cross-sectional information and accurate body outlines of patients destined for radiotherapy, using a radiotherapy simulator without any major modifications, has been investigated. The image intensifier of the simulator was moved laterally and a narrow fan beam of X-rays passed through the phantom onto the intensifier. Several television (TV) lines of the video signal from the TV camera were digitized by a frame grabber and stored for reconstruction. Multiple projections were acquired by rotating the gantry of the simulator. The field of view was enlarged by increasing the offset distance of the image intensifier and taking two sets of projections. Reconstruction was carried out by using the convolution and back-projection method. The gradient between pixel values in the reconstructed images was used to detect the outlines of structures in the images. The accuracy of outline detection was evaluated with images of a Rando phantom. The outlines of the images were compared with the actual outlines of the phantom. The spatial resolution of the simulator computed tomography (CT) was measured to be 4.05 mm. Large inhomogeneities could be clearly seen. The average difference between the measured and the actual outlines was 3.0 mm with a maximum difference of 10.0 mm at sharp curves in the outline. The simulator CT provides an inexpensive, alternative method of obtaining body outlines and does not require any modifications to the simulator. Data acquisition, processing and display can be performed on a personal computer with image processing facilities.

Head↗
PubMed2006

Dielectric measurement of individual microtubules using the electroorientation method.

Little is known about the electrostatic/dynamic properties of microtubules, which are considered to underlie their electrostatic interactions with various proteins such as motor proteins, microtubule-associated proteins, and microtubules themselves (lateral association of microtubules). To measure the dielectric properties of microtubules, we developed an experiment system in which the electroorientation of microtubules was observed under a dark-field microscope. Upon application of an alternating electric field (0.5-1.9 x 10(5) V/m, 10 kHz-3 MHz), the microtubules were oriented parallel to the field line in a few seconds because of the dipole moment induced along their long axes. The process of this orientation was analyzed based on a dielectric ellipsoid model, and the conductivity and dielectric constant of each microtubule were calculated. The analyses revealed that the microtubules were highly conductive, which is consistent with the counterion polarization model-counterions bound to highly negatively charged microtubules can move along the long axis, and this mobility might be the origin of the high conductivity. Our experiment system provides a useful tool to quantitatively evaluate the polyelectrolyte nature of microtubules, thus paving the way for future studies aiming to understand the physicochemical mechanism underlying the electrostatic interactions of microtubules with various proteins.

Electric Impedance↗