SU-E-l-01: Investigating the Dependence of 2D and 3D Scatter-To-Primary Ratios on Breast Density in Clinical Breast CT

PURPOSE

To characterize 2D and 3D scatter-to-primary ratios (SPR) and investigate the dependence of SPR on breast density based on clinicalpatient imaging on our dedicated SPECT-CT mammotomography system.

METHODS

As a part of an on-going IRB approved protocol, 7 consented women underwent a breast imaging study with our SPECT-CT system. Using a quasi-monochromatic x-ray cone beam and flat panel detector, 240 projections were obtained. 6 beam stop array (BSA) projections were also obtained over 40 degree intervals. The CT data were scatter corrected using a phantom-validated algorithm based on the BSA technique. For each projection, 2D scatter fluence was determined behind each beam stop shadow through the patient's breast, and cubic spline interpolated throughout the thresholded breast region. 2D SPRs were calculated as the average of 6 measured ratios of scatter projections to scatter corrected (primary) projections. Angular cubic spline interpolation was performed to obtain the remaining 234 azimuthal BSA projections for reconstruction correction. Corrected and uncorrected projection images were individually reconstructed and 3D SPRs calculated as the ratio of difference between primary and un-corrected volumes to primary volumes. Histograms of the reconstructed patient data-sets yielded distinct peaks representing linear attenuation coefficients of glandular+skin and fatty tissue. Percentage glandular and fatty tissue was estimated by fitting a double Gaussian to the histogram and integrating area under the curve.

RESULTS

Only 4 CT data sets devoid of motion and truncation artifacts were suitable for scatter correction. Preliminary results show that 2D SPR values peak at the center of breast volumes and were greatest (∼50%) for the most glandular breast, whereas 3D SPR values remained fairly constant throughout the breast and did not obviously correlate with density, consistent with prior phantom results.

CONCLUSIONS

2D SPR values are greater in breasts with higher glandular tissue composition, whereas 3D SPR values appear independent of breast composition. This work is funded by the National Cancer Institute of the National Institutes of Health grant RO1-CA096821, with partial support (JHP) from NIH T32-EB001040. MPT is the inventor of this CT technology, and is named as an inventor on the patent for this technology awarded to Duke University. If this technology becomes commercially successful, MPT and Duke could benefit financially.

High magnetic field quantum transport in Au nanoparticle-cellulose films

We report the magneto-transport properties of cellulose films comprising interconnected networks of gold nanoparticles (Au NPs). Cellulose is a biopolymer that can be made electrically conducting by cellulose regeneration in Au NP dispersions. The mechanism of electronic conduction in the Au-cellulose films changes from variable range hopping to metallic-like conduction with decreasing resistivity. Our experiments in high magnetic fields (up to 45 T) reveal negative magnetoresistance in the highly resistive films. This is attributed to the spin polarization of the Au NPs and the magnetic field induced suppression of electron spin flips during spin-polarized tunneling in the NP network.

Prediction of longitudinal functional outcomes in schizophrenia: the impact of baseline motivational deficits

Emerging evidence suggests that motivational deficits are a central component of negative symptoms in schizophrenia, and linked to functional impairment characterizing this illness. This study extends previous cross-sectional findings by examining the concurrent contributions of baseline motivational deficits, other negative symptoms, and other symptom domains on longitudinal functional outcomes in schizophrenia. Results of this longitudinal examination of 18 patients from our previous pilot study reveal that amotivation accounts for 74% and 72% of the variance in functional outcomes at baseline and 6-month follow-up, respectively. These findings further suggest a fundamental role for motivational deficits in predicting functional outcomes in schizophrenia.

Exposure to radio frequency electromagnetic fields from wireless computer networks: duty factors of Wi-Fi devices operating in schools

The growing use of wireless local area networks (WLAN) in schools has prompted a study to investigate exposure to the radio frequency (RF) electromagnetic fields from Wi-Fi devices. International guidelines on limiting the adverse health effects of RF, such as those of ICNIRP, allow for time-averaging of exposure. Thus, as Wi-Fi signals consist of intermittent bursts of RF energy, it is important to consider the duty factors of devices in assessing the extent of exposure and compliance with guidelines. Using radio packet capture methods, the duty factor of Wi-Fi devices has been assessed in a sample of 6 primary and secondary schools during classroom lessons. For the 146 individual laptops investigated, the range of duty factors was from 0.02 to 0.91%, with a mean of 0.08% (SD 0.10%). The duty factors of access points from 7 networks ranged from 1.0% to 11.7% with a mean of 4.79% (SD 3.76%). Data gathered with transmit time measuring devices attached to laptops also showed similar results. Within the present limited sample, the range of duty factors from laptops and access points were found to be broadly similar for primary and secondary schools. Applying these duty factors to previously published results from this project, the maximum time-averaged power density from a laptop would be 220 μW m(-2), at a distance of 0.5 m and the peak localised SAR predicted in the torso region of a 10 year old child model, at 34 cm from the antenna, would be 80 μW kg(-1).

Estimation of RF energy absorbed in the brain from mobile phones in the Interphone Study

Objectives

The objective of this study was to develop an estimate of a radio frequency (RF) dose as the amount of mobile phone RF energy absorbed at the location of a brain tumour, for use in the Interphone Epidemiological Study.

Methods

We systematically evaluated and quantified all the main parameters thought to influence the amount of specific RF energy absorbed in the brain from mobile telephone use. For this, we identified the likely important determinants of RF specific energy absorption rate during protocol and questionnaire design, we collected information from study subjects, network operators and laboratories involved in specific energy absorption rate measurements and we studied potential modifiers of phone output through the use of software-modified phones. Data collected were analysed to assess the relative importance of the different factors, leading to the development of an algorithm to evaluate the total cumulative specific RF energy (in joules per kilogram), or dose, absorbed at a particular location in the brain. This algorithm was applied to Interphone Study subjects in five countries.

Results

The main determinants of total cumulative specific RF energy from mobile phones were communication system and frequency band, location in the brain and amount and duration of mobile phone use. Though there was substantial agreement between categorisation of subjects by cumulative specific RF energy and cumulative call time, misclassification was non-negligible, particularly at higher frequency bands. Factors such as adaptive power control (except in Code Division Multiple Access networks), discontinuous transmission and conditions of phone use were found to have a relatively minor influence on total cumulative specific RF energy.

Conclusions

While amount and duration of use are important determinants of RF dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain. It is important to take these into account in analyses of risk of brain tumours from RF exposure from mobile phones.

Assessment of exposure to electromagnetic fields from wireless computer networks (wi-fi) in schools; results of laboratory measurements

Laboratory measurements have been carried out with examples of Wi-Fi devices used in UK schools to evaluate the radiofrequency power densities around them and the total emitted powers. Unlike previous studies, a 20 MHz bandwidth signal analyzer was used, enabling the whole Wi-Fi signal to be captured and monitored. The radiation patterns of the laptops had certain similarities, including a minimum toward the torso of the user and two maxima symmetrically opposed across a vertical plane bisecting the screen and keyboard. The maxima would have resulted from separate antennas mounted behind the top left and right corners of the laptop screens. The patterns for access points were more symmetrical with generally higher power densities at a given distance. The spherically-integrated radiated power (IRP) ranged from 5 to 17 mW for 15 laptops in the 2.45 GHz band and from 1 to 16 mW for eight laptops in the 5 GHz band. For practical reasons and because access points are generally wall-mounted with beams directed into the rooms, their powers were integrated over a hemisphere. These ranged from 3 to 28 mW for 12 access points at 2.4 GHz and from 3 to 29 mW for six access points at 5 GHz. In addition to the spherical measurements of IRP, power densities were measured at distances of 0.5 m and greater from the devices, and consistent with the low radiated powers, these were all much lower than the ICNIRP reference level.

Clostridium difficile infection in the absence of a colon

Clostridium difficile (CD) infection is almost always confined to the colon causing a spectrum of illness ranging from diarrhoea to fulminant colitis. CD infection of the small intestine has been described but the identification of CD toxin in the stoma effluent of a patient with an end ileostomy is rare. We describe a 91-year-old woman, with a history of proctocolectomy for ulcerative colitis, presenting with profuse ileostomy diarrhoea after a course of antibiotics. Ileostomy effluent was positive for CD toxin but the patient died despite appropriate treatment. This suggests that the small intestine is susceptible to CD infection in antibiotic-treated patients many years after a colectomy. CD enteritis should be considered in all patients with increased ileostomy diarrhoea despite the absence of a colon.

Synthesis of disubstituted 1,4-diazepines with affinity to GABAA-receptor subtypes

A series of tetrahydro-1 H-1,4-diazepines 4a-c, dihydro-1 H-1,4-diazepine 5 and pyrido diazepines 8 and 10 was prepared. Originated form dehydroacetic acid (DHA) and aromatic aldehydes cinnamoyl compounds 3a-c were obtained and converted with ethylenediamine to give tetrahydro-1H-1,4-diazepines 4a-c. For the synthesis of pyrido[1,2-d][1,4]diazepines 8 and 10 a new snythetic approach is described. Compounds 4b and 5 were investigated concerning their affinity to different benzodiazepine receptor subtypes. The determined IC50 values for 5 are 1.5 microM and 1.1 microM at 10 microM respectively.

Oxidation of Manganese and Formation of Mn(3)O(4) (Hausmannite) by Spore Coats of a Marine Bacillus sp

Isolated spore coats of a marine Bacillus species were incubated in 25 mM MnCl(2) at pH 7.5. Manganese precipitates, formed on the coat surfaces, were analyzed by transmission electron microscopy, electron diffraction, and energy-dispersive X-ray spectroscopy. Initially, an amorphous manganese oxide was observed on the coats which recrystallized to hausmannite after prolonged incubation in the MnCl(2) solution. The spore coats catalyze the oxidation of Mn(II) and have no structural influence on the final mineral phase precipitated.

Pharmacokinetic profile of immediate-release omeprazole in patients with gastro-oesophageal reflux associated with gastroparesis

BACKGROUND

Immediate-release omeprazole has a more rapid absorption compared with delayed-release omeprazole in asymptomatic volunteers. However, effects of delayed gastric emptying on omeprazole absorption remain unknown.

AIM

To compare pharmacokinetics between immediate and delayed-release omeprazole in patients with GERD associated with gastroparesis.

METHODS

Open-label, randomized, cross-over study was performed. Antireflux and prokinetic medications were discontinued. Subjects were randomized into: (i) Immediate-release omeprazole 40 mg suspension o.m. for 7 days, wash-out for 10-14 days, followed by delayed-release omeprazole 40 mg capsule o.m. for 7 days, or (ii) the same schedule in reverse order. On day 7, omeprazole concentrations were obtained before and up to 5 h after taking the study drug. Patient Assessment of GI Disorders-Symptom Severity Index was obtained.

RESULTS

A total of 12 women (mean age 51 years) completed the protocol. Time to maximal omeprazole concentration was significantly shorter for omeprazole. Maximal concentration was significantly greater for omeprazole, but total area under concentration-time curves was similar. Pharmacokinetic profile was less variable for immediate compared with delayed-release omeprazole.

CONCLUSIONS

Immediate-release omeprazole was associated with a more rapid absorption and less variable pharmacokinetic profile compared with delayed-release omeprazole in reflux patients associated with gastroparesis.

Effect of endogenous and synthetic antioxidants on hydrogen peroxide-induced guinea-pig colon contraction

OBJECTIVES AND DESIGN

The effects of the endogenous antioxidant alpha-lipoic acid on guinea pig colon smooth muscle contraction (Gpcc) induced by hydrogen peroxide were examined. Having previously shown that the histone deacetylase (HDAC) benzamide inhibitor MGCD0103 inhibits guinea-pig smooth muscle contraction, as do various sulfur-containing antioxidants, we asked whether hybrid compounds possessing both alpha-lipoic acid-derived antioxidant properties and HDAC inhibitory activity could inhibit Gpcc.

MATERIALS AND METHODS

Guinea pig colon (Gpc) was incubated at 37 degrees C with Krebs buffer; the four stimulants-hydrogen peroxide, carbachol, histamine, and sodium fluoride-were added independently. The response to each stimulant alone was compared with that in the presence of each of the test compounds: MGCD0103, alpha-lipoic acid, and two of their hybrids, UCL M084 and UCL M109.

RESULTS

NaF (10 mM), carbachol (0.05 microM), histamine (0.1 microM), and hydrogen peroxide (1 microM) produced Gpcc of about 50-60% above basal level. With the exception of MGCD0103 against hydrogen peroxide, all four test compounds at 1 microM-MGCD0103, alpha-lipoic acid, UCL M084, and UCL M109-produced a significant inhibition of 35-60% of Gpcc induced by hydrogen peroxide, NaF, and carbachol, although none reduced histamine or ovalbumin-induced Gpcc. Benzalkonium chloride (Bcl), a G-protein inhibitor, reduced the hydrogen peroxide-induced Gpcc by 35%.

CONCLUSIONS

Contraction by stimulants used to induce Gpcc is known to involve G-proteins. All four test compounds-MGCD0103, alpha-lipoic acid and two of their hybrids, UCL M084 and UCL M109-reduced Gpcc induced by NaF and carbachol, suggesting that G-protein pathway involvement is relevant to the action of the test compounds, as is also indicated by the Bcl-induced inhibition of hydrogen peroxide-induced contractions. Additionally, alpha-lipoic acid and the two hybrids showed >30% inhibition of hydrogen peroxide-induced contractions, consistent with the antioxidant properties of the 1,2-dithiolane ring.

Motivational deficits as the central link to functioning in schizophrenia: a pilot study

Negative symptoms have consistently been found to contribute to functional impairment in schizophrenia. In this pilot study, we sought to delineate the core negative symptoms that contribute to this functional impairment. Adult outpatients with schizophrenia were evaluated for the severity of positive, negative, cognitive, and depressive symptoms. The Quality of Life Scale was used to assess current functioning. Results from 21 participants revealed that a motivation was the sole predictor of functioning, accounting for 74% of the variance in current functioning. This suggests that motivational deficits are the central link between negative symptoms and functional impairment in schizophrenia.

Determinants of mobile phone output power in a multinational study: implications for exposure assessment

OBJECTIVES

The output power of a mobile phone is directly related to its radiofrequency (RF) electromagnetic field strength, and may theoretically vary substantially in different networks and phone use circumstances due to power control technologies. To improve indices of RF exposure for epidemiological studies, we assessed determinants of mobile phone output power in a multinational study.

METHODS

More than 500 volunteers in 12 countries used Global System for Mobile communications software-modified phones (GSM SMPs) for approximately 1 month each. The SMPs recorded date, time, and duration of each call, and the frequency band and output power at fixed sampling intervals throughout each call. Questionnaires provided information on the typical circumstances of an individual's phone use. Linear regression models were used to analyse the influence of possible explanatory variables on the average output power and the percentage call time at maximum power for each call.

RESULTS

Measurements of over 60,000 phone calls showed that the average output power was approximately 50% of the maximum, and that output power varied by a factor of up to 2 to 3 between study centres and network operators. Maximum power was used during a considerable proportion of call time (39% on average). Output power decreased with increasing call duration, but showed little variation in relation to reported frequency of use while in a moving vehicle or inside buildings. Higher output powers for rural compared with urban use of the SMP were observed principally in Sweden where the study covered very sparsely populated areas.

CONCLUSIONS

Average power levels are substantially higher than the minimum levels theoretically achievable in GSM networks. Exposure indices could be improved by accounting for average power levels of different telecommunications systems. There appears to be little value in gathering information on circumstances of phone use other than use in very sparsely populated regions.