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Hypoxic inhibition of K+ channels provides a link between low O2 and cell function, and in glossopharyngeal neurons hypoxic inhibition of a TWIK-related halothane-inhibitable K+ channel-1 (THIK-1)-like background K+ channel regulates neuronal function. In the present study, we examined directly the O2 sensitivity of recombinant THIK-1 channels, expressed in human embryonic kidney (HE293) cells. THIK-1 expression conferred a moderately outwardly rectifying halothane-inhibited and arachidonic acid-potentiated K+ current and invoked a strongly hyperpolarized resting membrane potential. Endogenous K+ currents in untransfected cells were unaffected by either agent. Hypoxia (P(O2), 20 mmHg) reversibly inhibited THIK-1 currents and caused membrane depolarization, effects that were occluded by halothane. Neither the mitochondrial complex I inhibitors rotenone, myxothiazol and sodium cyanide, nor the NADPH oxidase inhibitors diphenylene iodonium and phenylarsine oxide, were effective in inhibiting the O2-sensitivity of THIK-1. Thus, hypoxic inhibition of THIK-1 occurs by a mechanism dissimilar to that which regulates the activity of other members of the background K+ channel family. Given the O2 sensitivity of THIK-1 channels and their abundant expression in the CNS, we raise for the first time the possibility of a physiological and/or pathological role for these channels during brain ischemia.

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PURPOSE: To compare the effectiveness of temazepam and midazolam hydrochloride with or without fentanyl citrate versus a placebo in promoting patient acceptance of diagnostic aortofemoral arteriography. MATERIALS AND METHODS: One hundred twenty-five patients undergoing aortofemoral arteriography were prospectively and randomly assigned to one of four treatment arms: placebo (group A), oral temazepam (group B), intravenous midazolam (group C), or intravenous midazolam and fentanyl (group D). Patients were blinded to the administered sedative. Five-point scales were used to assess degree of patient discomfort, willingness to undergo the same procedure again, patient compliance, and preprocedural anxiety. RESULTS: There was no difference between patient groups in willingness to return for a repeat procedure (P: =.89). Group C patients were less compliant during the procedure (P: =.034). Mean patient discomfort scores were 1.81 for group A, 1.84 for group B, 1. 53 for group C, and 1.27 for group D. Discomfort experienced during the procedure was not related to the degree of preprocedural anxiety (P: =.42). Patients who had previously undergone arteriography reported a higher level of pain than did those who had not (P: =. 021). CONCLUSION: Most patients experienced only low-level discomfort during diagnostic aortofemoral arteriography. In the authors' opinion, conscious sedation should only be used selectively, not routinely, for diagnostic aortofemoral arteriography.

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Ultrasound guided graded manual compression therapy has become the standard treatment for femoral artery pseudoaneurysms. It entails blunt ultrasound probe compression on the neck of the aneurysm for considerable periods of time. We describe a technique using digital compression after ultrasound localization of the neck enabling easier and more effective targeting of the manual pressure. Preliminary experience in six consecutive cases has shown it to be effective, safe and to have relatively short compression times. Ultrasound guided digital compression has the potential to deliver more effective pressure making this often onerous procedure less demanding on both patient and operator.

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AIM: To report problems in the tethering catheter shaft of the Tempofilter, temporary caval filter. MATERIALS AND METHODS: Two cases are reported where the tethering catheter shaft of the Tempofilter buckled within the jugular vein. RESULTS: Buckling of the tethering shaft caused cephalic migration of the filter into the right atrium. Both filters were uneventfully removed without adverse sequelae. CONCLUSION: These cases demonstrate another mechanism of tethering shaft shortening which results in unexpected migration of the filter. This device is potentially dangerous because of the liability of the tethering cather to buckle at or near the insertion site with cephalic migration of the filter. Improvements in the tethering catheter mechanism need to be made before further patient usage.

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Visual transduction in Drosophila is a G protein-coupled phospholipase C-mediated process that leads to depolarization via activation of the transient receptor potential (TRP) calcium channel. Inactivation-no-afterpotential D (INAD) is an adaptor protein containing PDZ domains known to interact with TRP. Immunoprecipitation studies indicate that INAD also binds to eye-specific protein kinase C and the phospholipase C, no-receptor-potential A (NORPA). By overlay assay and site-directed mutagenesis we have defined the essential elements of the NORPA-INAD association and identified three critical residues in the C-terminal tail of NORPA that are required for the interaction. These residues, Phe-Cys-Ala, constitute a novel binding motif distinct from the sequences recognized by the PDZ domain in INAD. To evaluate the functional significance of the INAD-NORPA association in vivo, we generated transgenic flies expressing a modified NORPA, NORPAC1094S, that lacks the INAD interaction. The transgenic animals display a unique electroretinogram phenotype characterized by slow activation and prolonged deactivation. Double mutant analysis suggests a possible inaccessibility of eye-specific protein kinase C to NORPAC1094S, undermining the observed defective deactivation, and that delayed activation may similarly result from NORPAC1094S being unable to localize in close proximity to the TRP channel. We conclude that INAD acts as a scaffold protein that facilitates NORPA-TRP interactions required for gating of the TRP channel in photoreceptor cells.

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OBJECTIVE: We performed a retrospective review of trauma patients who had undergone both pelvic angiography and preangiographic i.v. contrast-enhanced CT to determine whether CT can accurately demonstrate the presence or absence of pelvic bleeding in patients with multisystem trauma and major pelvic fractures. SUBJECTS AND METHODS: We reviewed the medical records and imaging studies of all patients, identified through a trauma radiology database, who had undergone pelvic angiography and preangiographic contrast-enhanced CT during a 48-month period. Results of CT scans were recorded by consensus interpretation of three radiologists without knowledge of angiographic findings. Sites of contrast material extravasation seen on CT scans were noted and compared with sites of bleeding or vascular injury identified by selective pelvic angiography. RESULTS: Thirty patients with blunt trauma and pelvic fractures underwent both pelvic angiography and preangiographic CT studies. Findings on pelvic angiograms were positive at 26 sites in 19 patients and included contrast agent extravasation at 23 sites and vessel abnormalities without extravasation at three sites. Preangiographic pelvic CT scans showed contrast agent extravasation at 20 sites in 16 patients. Three patients had no contrast agent extravasation demonstrated by CT but had bleeding demonstrated by angiography. CT detected bleeding in 16 of 19 patients who had extravasation or vascular injury demonstrated by angiography, for a sensitivity of 84%. Results of pelvic angiography were negative in 11 patients, and none had evidence of bleeding on preangiographic CT scans. Two sites of contrast agent extravasation identified in two patients by CT did not show bleeding at angiography, for a specificity of 85% for the detection of bleeding. The overall accuracy of CT for determining the presence or absence of bleeding was 90%. CONCLUSION: Knowledge of sites of ongoing hemorrhage is crucial for optimizing the sequence of diagnostic and therapeutic studies in patients with blunt trauma. Contrast-enhanced CT of the pelvis, which is often performed for hemodynamically stable trauma patients, is a noninvasive technique that is highly accurate in determining the presence or absence of ongoing pelvic hemorrhage. This information can assist in initial management decisions involving patients with multisystem trauma and major pelvic fractures.

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A simple and safe technique for examining the ileal pouch in the post-operative period is described, and the findings in 85 patients reviewed. Extravasation from the ileo-anal anastomosis was seen in 10/85 (11%). In 14/85 (16%) the lateral view of the filled pouch showed a presacral space > 4 cm, which in 10 (71%) was due to a significant abnormality: six having an anastomotic leak with presacral abscess, two a large presacral haematoma, and two an abscess without anastomotic leak. Pouchography is recommended as a routine examination prior to closure of the covering ileostomy.

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PURPOSE: To develop a system for three-dimensional (3D) ultrasonography (US) that readily interfaces with conventional equipment and to apply this system to fetal imaging. MATERIALS AND METHODS: An acquisition system based on transputer technology records from the video output of standard clinical scanners was interfaced with a position-sensing device, one component of which was attached to the US probe. The method differs from other 3D US methods as any conventional probe may be used, freehand scanning is possible, and no line-of-sight limitations operate. Such scanning was performed of 25 fetuses with gestation ages of 7-30 weeks. RESULTS: Acquisition typically took 3-5 seconds. Acquisition and reconstruction were successful in 17 of 25 cases and were easiest to perform in the first and second trimester. Surface rendering revealed anatomic detail that was not depicted with two-dimensional scanning. CONCLUSION: The technique has the potential for recording complete anatomic studies for review and visualization of detail that is difficult to perceive on conventional US scans.

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Sarcoidosis is a relatively common disease with protean clinical manifestations. Involvement of the parotid glands in the acute presentation is well recognized but the grey scale and colour Doppler appearances are less well so. These are described in a case where imaging and biopsy proved valuable in the diagnosis of acute sarcoid presenting as sicca syndrome.

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PURPOSE: To determine the role of color Doppler imaging (CDI) in diagnosis of prostate cancer. MATERIALS AND METHODS: Transrectal ultrasound (TRUS) and CDI were performed in 456 patients with possible prostate cancer. Of these patients, 158 underwent prostate biopsy, and these formed the study group. RESULTS: The frequency of malignancy was 47% (75 of 158). Of 136 TRUS-positive cases, 72 were malignant and 64 benign. Of 84 CDI-positive cases, 65 were malignant and 19 benign (chi 2 = 12.18, P < .001). Thirteen percent of histopathologically proved cases (10 of 75) were normal at CDI. TRUS alone had a sensitivity of 96% and a positive predictive value (PPV) of 0.53. The addition of CDI increased the PPV to 0.77 but reduced the sensitivity to 87%. In only one case out of 158 did CDI suggest the diagnosis of malignancy independently of TRUS. CONCLUSION: CDI improves the PPV of TRUS but appears to have little additional value over TRUS alone in diagnosis of prostate cancer.

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Two patients with obstructive biliary symptoms were shown to have dilated bile ducts on ultrasound. Within the lumen of both distal common ducts (CBD) large low echogenicity polypoid masses without acoustic shadowing were seen. MRI in one patient showed a polypoid filling defect in the lower CBD corresponding to the ultrasound appearance. Instrumentation at the lower end of both CBDs caused disintegration of the polypoid configuration resulting in the more typical layered appearance of biliary sludge. Sludge in the gall-bladder as seen on ultrasound is rarely known to cause a pseudotumour appearance. It has not previously been reported as occurring in the CBD and awareness of the tumefactive appearance of biliary sludge in the common duct is important and should help avoid possible misinterpretation.

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In two patients with Crohn's disease, strictureplasties had been marked operatively by a metal clip, so that definitive location on subsequent small bowel examination was possible. Each strictureplasty presented radiologically as a short annular constriction with apparently shouldered edges and parallel lumen. Similar radiological features were found in five other patients with strictureplasties, suggesting that a pseudotumoral appearance is characteristic of strictureplasty. Attention is drawn to this finding to avoid confusion with malignancy.

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A man presented with unilateral visual blurring associated with bilateral retinal periphlebitis which was felt to be a complication of his biopsy-proven active ulcerative colitis. Retinal periphlebitis has been associated rarely with some forms of colitis but we can find no report of its occurrence in association with ulcerative colitis although other ocular inflammatory disorders are well recognized.

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