Y-24180 ((+/-)-4-(2-chlorophenyl)-2-[2-(4-isobutylphenyl)ethyl]-6,9-dim eth yl-6H-thieno[3,2-f] [1,2,4]triazolo[4,3-a] [1,4] diazepine), an antagonist of platelet-activating factor (PAF) receptor, has already been reported to inhibit leukotriene B4 (LTB4)-induced activation of polymorphonuclear leukocytes. In this article, to clarify the mechanism of inhibition of LTB4-induced activation by Y-24180, we examined the effect of Y-24180 on LTB4-induced increase in intracellular calcium ion ([Ca2+]i) level of human polymorphonuclear leukocytes at a single cell level using a laser scanning confocal microscope. Preincubation with Y-24180 significantly inhibited the increase in [Ca2+]i level at 0.3-3 microM, while WEB 2086 (4-[3-[4-(2-chlorophenyl)-9-methyl-6H-thieno[3,2-f][1,2,4]triazolo[4,3-a ][1,4]diazepin-2-yl]propionyl]morpholine), another PAF receptor antagonist, did not show the inhibitory effect at 3-30 microM, indicating that the difference in potency between these compounds was more than 100-fold. The LTB4-induced increase in [Ca2+]i level was suppressed by microinjection of anti-PAF antibody, but not control antibody, into leukocytes. Microinjection of Y-24180 at 0.003-0.03 microM or WEB 2086 at 0.03-0.3 microM into leukocytes also inhibited the LTB4-induced increase. The microinjection of WEB 2086 at the 10-fold greater concentrations than those of Y-24180 inhibited to the almost equal level to that obtained by Y-24180. In addition, microinjection of PAF into leukocytes induced the increase in [Ca2+]i level. Preincubation with Y-24180 at 1 or 3 microM significantly attenuated the PAF microinjection-induced increase, but WEB 2086 showed little effect at 3-30 microM. These results indicate that Y-24180 inhibits LTB4-induced activation of leukocytes by suppressing the increase in [Ca2+]i level and the inhibitory effect is mediated by antagonistic action against intracellular PAF-induced up-regulation of [Ca2+]i level. The difference in inhibitory activity for the increase in [Ca2+]i level between Y-24180 and WEB 2086 when these are added in the culture medium may depend upon their aptitude for the transmembrane influx.

Azepines↗

PubMedDate not supplied

Magnetic resonance imaging of myelofibrosis. STIR and gadolinium-enhanced MR images.

MR images of myelofibrosis were assessed in twelve patients. Myelofibrosis showed low intensity in T1-weighted images, high intensity in STIR images, and enhancement after gadolinium injection. MR spectroscopy detected a large water resonance. MR imaging was consistent with histological findings and useful in evaluating the extracellular space in bone marrow of myelofibrosis, but it was of no value in differentiating between primary and secondary myelofibrosis.

Bone Marrow↗

PubMedDate not supplied

Metallic artifacts of coronary and iliac arteries stents in MR angiography and contrast-enhanced CT.

Metallic artifacts of intravascular stents were assessed with MR angiography and contrast-enhanced spiral CT. Stainless steel showed less metal artifact than tantalum stent in CT. Metallic artifact in coronary and iliac arteries treated with tantalum stent was not remarkable in MR angiography. Contrast-enhanced CT might be preferable to assess patency of arteries treated with stainless steel stent. while MR angiography was useful in depicting intraluminal signal in tantalum stent.

Aged↗

PubMedDate not supplied

Ultrasound-guided infraclavicular brachial plexus block: an alternative technique to anatomical landmark-guided approaches.

BACKGROUND AND OBJECTIVES: Infraclavicular brachial plexus block has been used less than other approaches because of its less uniform landmarks and the necessity of a longer needle, which increases the patient's discomfort. To overcome these drawbacks, we applied ultrasound guidance to infraclavicular approach and prospectively evaluated its feasibility and usefulness in 60 patients undergoing upper extremity surgery. METHODS: A 7.0-MHz ultrasound probe was placed near the lower edge of the clavicle, and a transverse view of the subclavian artery and vein was visualized. Using a needle guide, a 23-gauge needle was advanced under real-time ultrasound guidance, and 1.5% lidocaine with 1:200,000 epinephrine was injected near the subclavian artery, 15 mm medially and 15 mm laterally to the artery. The extent of sensory and motor block was evaluated at 30 minutes after the injection. RESULTS: An adequate ultrasound image was obtained for all the patients. In 57 patients (95%), surgery was performed without supplementation of any other anesthetics or analgesics. The complete sensory block was obtained in 100% of patients for the musculocutaneous and medial antebrachial cutaneous nerves, 96.7% for the median nerve, and 95% for the ulnar and radial nerves. The complete motor block was achieved in 100% of patients for the musculocutaneous nerve, 96.7% for the median nerve, 90% for the ulnar nerve, and 93.3% for the radial nerve. No evidence of any complications was identified. CONCLUSIONS: Real-time ultrasound guidance facilitates accurate infraclavicular approach to the brachial plexus. It could be used as an alternative to the landmark-guided techniques.

Adolescent↗

PubMedDate not supplied

Introduction of 6-formylcytidine into a Myb binding sequence.

Single 6-formylcytidine was introduced into a oligonucleotide duplex (23 mers) as a substitute for thymidine in the Myb binding sequence of 3'-TTGAC-5'. The modified duplex showed Tm of 67 degrees C, which was six degrees lower than the Tm of the native duplex. Binding affinity of the 23-mers to the Myb protein was estimated by electrophoretic mobility shift assays, and the binding was almost completely abolished.

Binding Sites↗

PubMedDate not supplied

Effects of changing the type of H2-blocker in the treatment of H2-blocker-resistant ulcers: comparison of roxatidine acetate hydrochloride and other H2-blockers.

The efficacy of switching from one type of H2-receptor antagonist (H2-blocker) to another, in the treatment of H2-blocker-resistant ulcers was investigated using H2-blockers with five-membered rings (five-membered-ring agents)--such as cimetidine, ranitidine and famotidine--and an H2-blocker with a six-membered ring, roxatidine. By switching from a five-membered-ring agent to roxatidine in the treatment of five-membered-ring resistant ulcers (study I), gastric ulcers were healed in nine of 19 patients (47%) and duodenal ulcers were healed in eight of nine patients (89%). By switching from roxatidine to one of the five-membered-ring agents in the treatment of roxatidine-resistant ulcers (study II), gastric ulcer was healed in six of 15 patients (40%), and duodenal ulcer was healed in 4 of 10 patients (40%). Particularly in the case of duodenal ulcers, the switch to treatment with roxatidine, which has a different chemical structure from the five-membered-ring agents, may be useful in the treatment of five-membered-ring-resistant ulcers.

Adult↗

PubMedDate not supplied

Multi-directional positron imaging: evaluation of cancer detection with 2-(F-18)-fluoro-2-deoxy-D-glucose.

We developed a multi-directional positron imaging system for the whole body in order to evaluate the spatial distribution of radiopharmaceuticals. A positron emission tomography (PET) scanner with ring detectors was modified to provide 54 directional planar images with a three-dimensional appearance by using cinematic display. The initial clinical evaluation was performed on two normal volunteers and 17 cancer patients with 32 foci. Images were obtained approximately one hour after the intravenous administration of 2-(F-18)-fluoro-2-deoxy-D-glucose. In all 19 subjects, good quality images with a three-dimensional appearance were obtained. We were able to visualize 16 of 20 (80%) lesions that were three centimeters or more in greatest diameter. In contrast, only seven of 12 (58%) lesions less than three centimeters in greatest diameter were identified. The overall detectability of lesions was 72%. These results suggest that this system will be useful for tumor detection.

Aged↗

PubMedDate not supplied

[Proceedings: 13. RNA synthesis in different phases of cell cycle of chick embryo cells (author's transl)].

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Animals↗

PubMedDate not supplied

Evaluation of the performance of a whole-body positron imaging system with attenuation correction.

A PET scanner with ring detectors has been modified to accomplish whole-body imaging with attenuation correction. To evaluate the performance of this system, phantom studies and clinical studies were performed in seven patients. The transaxial resolution (FWHM) at the center of the field was 8.6 mm, and the axial resolution was 12.3 mm. The counts on the images with attenuation correction were linearly related to accumulation of the radiopharmaceuticals, and attenuation correction was made accurately. The transmission scan from the top of the head to the thigh, about 110 cm in length, required 36 minutes, and one emission scan required 18 minutes. The total study time for one transmission scan and three sequential emission scans was 1.9 hours. In clinical studies, attenuation correction made the discrimination of organs clearer, and would facilitate the detection of tumors, especially those in the high attenuation organs or matter. The use of this system made it possible to obtain quantitative whole-body positron images with adequate diagnostic quality within a reasonable scanning time.

Aged↗

PubMedDate not supplied

Classification of hematopoietic regions in out-of-phase T1-weighted images: a quantitative comparison study with T1-weighted and STIR images.

The hematopoietic regions were classified into two groups on the basis of out-of-phase T1-weighted images (op-T1WI): regions with lower intensity than that of muscle (LH) and regions with intensity equal to or higher than that of muscle (HH). We quantitatively evaluated the differences in signal intensity between LH and HH in order to examine this classification. Forty-two hematopoietic areas in aplastic anemia were classified into two groups of 23 LH and 19 HH. The signal ratios of hematopoietic areas to muscle on T1WI and STIR were calculated, and the differences between LH and HH were statistically evaluated. The signal ratios of LH were significantly higher on T1WI and lower on STIR than those of HH (unpaired t-test, p < 0.05). This result indicated that LH consisted of more hypocellular marrow than HH. Op-T1WI were useful in differentiating between LH and HH and defining the degree of hematopoiesis in aplastic anemia.

Adipose Tissue↗