Automated localization of the prostate at the time of treatment using implanted radiopaque markers: technical feasibility

PURPOSE: Prostate movement is a major consideration in the formation of target volumes for conformal radiation therapy of prostate cancer. The goal of this study was to determine the technical feasibility of using implanted radiopaque markers and digital imaging to localize the prostate at the time of treatment, thus allowing for reduction of the margin required for uncertainty in target position. METHODS AND MATERIALS: Radiopaque markers implanted around the prostate prior to treatment are visible on electronic radiographs generated with a portal imager or diagnostic imaging device. The locations of the images of these markers on the digital radiographs were automatically determined by a template-matching algorithm. The coordinates of the markers were found by projecting rays through the marker locations on orthogonal radiographs using a three-dimensional (3D) point-matching algorithm. Prostate and/or patient movement was inferred from the marker displacements. Images generated from known movements of a phantom with implanted markers were tested with this algorithm. Locations of markers from daily images of patients with implanted markers were determined by both manual and automatic techniques to determine the efficacy of automated localization on typical clinical images. RESULTS: Prostate movements can be automatically detected in a phantom using low-energy photons within 30 s after image acquisition and with a precision of better than 1 mm in translation and 1 degree in rotation (indistinguishable from the uncertainty in measuring precision). CONCLUSION: The studies show that on-line repositioning of the patient based on localization of the markers at the time of treatment is feasible, and may reduce the uncertainty in prostate location when combined with practical on-line repositioning techniques.     

Magnetic resonance imaging of the pelvic floor in patients with obstructed defaecation

BACKGROUND: Evacuation proctography and measurements of anorectal physiology are frequently used to clarify the pathophysiology of obstructed defaecation. In some patients these tests are normal, despite convincing clinical evidence of defaecatory difficulty. The aim of this study was to determine whether magnetic resonance imaging (MRI) could reveal pelvic floor abnormality in patients with obstructed defaecation. METHODS: Eleven women with obstructed defaecation, in whom evacuation proctography and anorectal physiology were normal, were examined by MRI, using a fast gradient echo sequence. Measurements of pelvic visceral and muscular descent were taken at rest and during straining, and compared with those obtained from 13 asymptomatic volunteers. RESULTS: Patients with obstructed defaecation had significantly greater pelvic visceral descent (P < 0.05), levator muscle descent (P = 0.04), levator plate angle change (P = 0.003) and increase in the area of the pelvic floor hiatus (P = 0.0002) than asymptomatic volunteers. CONCLUSION: MRI demonstrated marked pelvic visceral and levator muscle descent in women with obstructed defaecation, despite normal evacuation proctography and anorectal physiology. MRI should be considered if these examinations have been normal.     

Flecainide overdose: is cardiopulmonary support the treatment?

Flecainide toxicity can impair cardiac function and precipitate circulatory collapse, which in turn depresses clearance and redistribution of flecainide. Treatment directed at improving cardiac function is often ineffective in the presence of persistently increased flecainide levels. We report a novel approach to severe flecainide overdose using peripheral cardiopulmonary bypass support (CBS) to maintain perfusion of the liver, thereby allowing clearance of the drug. CBS was initiated to resuscitate a young woman who had ingested flecainide in a suicide attempt. The patient had an agonal rhythm, no effective blood pressure, and a flecainide level of 5.4 micrograms/mL (therapeutic range, .2 to 1.0 microgram/mL). During 10 hours of CBS, the flecainide level decreased to 1.4 micrograms/mL, a half-life of 6 hours. Effective cardiac rhythm and blood pressure returned. CBS successfully supported this patient until the flecainide level decreased as a result of redistribution and normal clearance mechanisms. Unfortunately, because of severe neurologic damage sustained at the time of overdose, the patient died 4 days after admission.     

Correlates of battering among 997 men: family history, adjustment, and attitudinal differences

In order to identify the characteristics associated with physical abuse of female partners, a detailed questionnaire was administered to 997 men who were recruited from either a forensic out-patient clinic (780) or from a community based employment center (217). This questionnaire sampled family and personal history, criminal behavior, psychopathology, and attitudes towards violence. Based upon self-report, the sample was divided into 184 non-abusive men, 517 moderately abusive men, and 296 severely abusive men. The full sample (997) was randomly divided into two subsamples and then, using a cross-validation design, group differences were identified in both subsamples on 46 of the 93 variables examined in this study. All significant effects were linear, such that the average scores of the severely abusive men were worse than the scores of the abusive men who, in turn, scored worse than the non-abusive men. In general, both groups of abusive men reported high rates of violence during childhood (both as victims and perpetrators), antisocial personality disorder, subjective distress, marital maladjustment, attitudes tolerant of spouse assault, and a range of impulsive behaviors (impulsive violence, substance abuse, motor vehicle accidents). The factors that correlated with abuse in the total sample also correlated with abuse in the community sample.     

Metanil yellow: a bifunctional inducer of hepatic phase I and phase II xenobiotic-metabolizing enzymes

Metanil yellow, a non-permitted food colour, has been found in various foodstuffs. The induction potential of metanil yellow on hepatic microsomal cytochrome P-450 (P-450)-dependent monooxygenases and cytosolic detoxification enzymes, namely, glutathione S-transferase (GST) and quinone reductase (QR), was investigated. Oral administration of metanil yellow (430 mg/kg body weight) to four animals for seven days caused significant induction of hepatic P-450 (48%) and its dependent aryl hydrocarbon hydroxylase (100%) activity and cytosolic GST (136%) and QR (92%) activities. Parenteral administration of metanil yellow (80 mg/kg body weight) to another set of four animals for 3 days resulted in higher induction of ethoxyresorufin-O-deethylase (228%) as compared to other monooxygenases (64-92%), while GST and QR were also found to be induced (59-95%). Spectra of metanil yellow-induced microsomes showed an increase in P-450 with a shift of 2.2 nm in the soret region. The results suggest that metanil yellow acts as a bifunctional inducer of specific isozymes of P-450 and cytosolic enzymes and thus may involve the cytosolic aryl hydrocarbon (Ah) receptor for this type of induction.     

RNA-protein interactions within the 3 ' untranslated region of vimentin mRNA

Several functions have been attributed to protein binding within the 3'untranslated region (3'UTR) of mRNA, including mRNA localization, stability, and translational repression. Vimentin is an intermediate filament protein whose 3'untranslated sequence is highly conserved between species. In order to identify sequences that might play a role in vimentin mRNA function, we synthesized32P-labeled RNA from different regions of vimentin's 3'UTR and assayed for protein binding with HeLa extracts using band shift assays. Sequences required for binding are contained within a region 61-114 nucleotides downstream of the stop codon, a region which is highly conserved from Xenopus to man. As judged by competition assays, binding is specific. Solution probing studies of 32P-labeled RNA with various nucleases and lead support a complex stem and loop structure for this region. Finally, UV cross-linking of the RNA-protein complex identifies an RNA binding protein of 46 kDa. Fractionation of a HeLa extract on a sizing column suggests that in addition to the 46 kDa protein, larger complexes containing additional protein(s) can be identified. Vimentin mRNA has been shown to be localized to the perinuclear region of the cytoplasm, possibly at sites of intermediate filament assembly. To date, all sequences required for localization of various mRNAs have been confined to the 3'UTR. Therefore, we hypothesize that this region and associated protein(s) might be important for vimentin mRNA function such as in localization.