Improvements in the robustness and accuracy of bioluminescence tomographic reconstructions of distributed sources within small animals

High quality three-dimensional bioluminescence tomographic (BLT) images, if available, would constitute a major advance and provide much more useful information than the two-dimensional bioluminescence images that are frequently used today. To-date, high quality BLT images have not been available, largely because of the poor quality of the data being input into the reconstruction process. Many significant confounds are not routinely corrected for and the noise in this data is unnecessarily large and poorly distributed. Moreover, many of the design choices affecting image quality are not well considered, including choices regarding the number and type of filters used when making multispectral measurements and choices regarding the frequency and uniformity of the sampling of both the range and domain of the BLT inverse problem. Finally, progress in BLT image quality is difficult to gauge owing to a lack of realistic gold-standard references that engage the full complexity and uncertainty within a small animal BLT imaging experiment. Within this dissertation, I address all of these issues. I develop a Cerenkov-based gold-standard wherein a Positron Emission Tomography (PET) image can be used to gauge improvements in the accuracy of BLT reconstruction algorithms. In the process of creating this reference, I discover and describe corrections for several confounds that if left uncorrected would introduce artifacts into the BLT images. This includes corrections for the angle of the animal’s skin surface relative to the camera, for the height of each point on the skin surface relative to the focal plane, and for the variation in bioluminescence intensity as a function of luciferin concentration over time. Once applied, I go on to derive equations and algorithms that when employed are able to minimize the noise in the final images under the constraints of a multispectral BLT data acquisition. These equations and algorithms allow for an optimal choice of filters to be made and for the acquisition time to be optimally distributed among those filtered measurements. These optimizations make use of Barrett’s and Moore-Penrose pseudoinverse matrices which also come into play in a paradigm I describe that can be used to guide choices regarding sampling of the domain and range

Preclinical efficacy of hK2 targeted [177Lu]hu11B6 for prostate cancer theranostics

Androgen ablating drugs increase life expectancy in men with metastatic prostate cancer, but resistance inevitably develops. In a majority of these recurrent tumors, the androgen axis is reactivated in the form of increased androgen receptor (AR) expression. Targeting proteins that are expressed as a down-stream effect of AR activity is a promising rationale for management of this disease. The humanized IgG1 antibody hu11B6 internalizes into prostate and prostate cancer (PCa) cells by binding to the catalytic cleft of human kallikrein 2 (hK2), a prostate specific enzyme governed by the AR-pathway. In a previous study, hu11B6 conjugated with Actinium-225 (225Ac), a high linear energy transfer (LET) radionuclide, was shown to generate an AR-upregulation driven feed-forward mechanism that is believed to enhance therapeutic efficacy. We assessed the efficacy of hu11B6 labeled with a low LET beta-emitter, Lutetium-177 (177Lu) and investigated whether similar tumor killing and AR-enhancement is produced. Moreover, single-photon emission computed tomography (SPECT) imaging of 177Lu is quantitatively accurate and can be used to perform treatment planning. [177Lu]hu11B6 therefore has significant potential as a theranostic agent. Materials and Methods: Subcutaneous PCa xenografts (LNCaP s.c.) were grown in male mice. Biokinetics at 4-336 h post injection and uptake as a function of the amount of hu11B6 injected at 72 h were studied. Over a 30 to 120-day treatment period the therapeutic efficacy of different activities of [177Lu]hu11B6 were assessed by volumetric tumor measurements, blood cell counts, molecular analysis of the tumor as well as SPECT/CT imaging. Organ specific mean absorbed doses were calculated, using a MIRD-scheme, based on biokinetic data and rodent specific S-factors from a modified MOBY phantom. Tumor tissues of treated xenografts were immunohistochemically (IHC) stained for Ki-67 (proliferation) and AR, SA-β-gal activity (senescence) and analyzed by digital autoradiography (DAR). Results: Organ-to-blood and tumor-to-blood ratios were independent of hu11B6 specific activity except for the highest amount of antibody (150 µg). Tumor accumulation of [177Lu]hu11B6 peaked at 168 h with a specific uptake of 29 ± 9.1 percent injected activity per gram (%IA/g) and low accumulation in normal organs except in the submandibular gland (15 ± 4.5 %IA/g), attributed to a cross-reaction with mice kallikreins in this organ, was seen. However, SPECT imaging with therapeutic amounts of [177Lu]hu11B6 revealed no peak in tumor accumulation at 7 d, probably due to cellular retention of 177Lu and decreasing tumor volumes. For [177Lu]hu11B6 treated mice, tumor decrements of up to 4/5 of the initial tumor volume and reversible myelotoxicity with a nadir at 12 d were observed after a single injection. Tumor volume reduction correlated with injected activity and the absorbed dose. IHC revealed retained expression of AR throughout treatment and that Ki-67 staining reached a nadir at 9-14 d which coincided with high SA- β-gal activity (14 d). Quantification of nuclei staining showed that Ki-67 expression correlated negatively with activity uptake. AR expression levels in cells surviving therapy compared to previous timepoints and to controls at 30 d were significantly increased (p = 0.017). Conclusions: This study shows that hu11B6 labeled with the low LET beta-emitting radionuclide 177Lu can deliver therapeutic absorbed doses to prostate cancer xenografts with transient hematological side-effects. The tumor response correlated with the absorbed dose both on a macro and a small scale dosimetric level. Analysis of AR staining showed that AR protein levels increased late in the study suggesting a therapeutic mechanism, a feed forward mechanism coupled to AR driven response to DNA damage or clonal lineage selection, similar to that reported in high LET alpha-particle therapy using 225Ac labeled hu11B6, however emerging at a later timepoint

Blood, men and tears: keeping IUDs in place in Bangladesh.

The Intra-Uterine Device (IUD) is an effective method of contraception, but in Bangladesh is associated with high levels of discontinuation within the first year. This study involved data collection from a retrospective cohort of women who had an IUD inserted 12 months earlier. In the cohort, 330 women were interviewed to identify factors associated with discontinuation. Later, 20 women, of the 103 who reported discontinuing because of excessive menstrual bleeding, were interviewed again and in depth about these issues. Of 330 women who had an IUD inserted, 47.3% had discontinued use one year post-insertion. In univariate and multivariate analyses, IUD discontinuation was strongly associated with side-effects (heavier periods; abdominal pain) and spousal factors (not discussing IUD with husband pre-insertion), but not with service delivery factors. In-depth interviews with women who reported excessive blood loss as the main reason for discontinuation found a doubling of both menstrual days and blood loss after IUD insertion. In Bangladesh, women cannot pray, have sexual intercourse, perform household tasks or participate in community activities during menstruation. Thus, women with menstrual side-effects faced serious physical, social and psychological challenges that made continuation difficult. Among those who discontinued, spouses were generally unsupportive and sometimes abusive, particularly when not involved in the decision to use the IUD

Violence against female sex workers in Karnataka state, south India: impact on health, and reductions in violence following an intervention program.

ABSTRACT: BACKGROUND: Violence against female sex workers (FSWs) can impede HIV prevention efforts and contravenes their human rights. We developed a multi-layered violence intervention targeting policy makers, secondary stakeholders (police, lawyers, media), and primary stakeholders (FSWs), as part of wider HIV prevention programming involving >60,000 FSWs in Karnataka state. This study examined if violence against FSWs is associated with reduced condom use and increased STI/HIV risk, and if addressing violence against FSWs within a large-scale HIV prevention program can reduce levels of violence against them. METHODS: FSWs were randomly selected to participate in polling booth surveys (PBS 2006-2008; short behavioural questionnaires administered anonymously) and integrated behavioural-biological assessments (IBBAs 2005-2009; administered face-to-face). RESULTS: 3,852 FSWs participated in the IBBAs and 7,638 FSWs participated in the PBS. Overall, 11.0% of FSWs in the IBBAs and 26.4% of FSWs in the PBS reported being beaten or raped in the past year. FSWs who reported violence in the past year were significantly less likely to report condom use with clients (zero unprotected sex acts in previous month, 55.4% vs. 75.5%, adjusted odds ratio (AOR) 0.4, 95% confidence interval (CI) 0.3 to 0.5, p < 0.001); to have accessed the HIV intervention program (ever contacted by peer educator, 84.9% vs. 89.6%, AOR 0.7, 95% CI 0.4 to 1.0, p = 0.04); or to have ever visited the project sexual health clinic (59.0% vs. 68.1%, AOR 0.7, 95% CI 0.6 to 1.0, p = 0.02); and were significantly more likely to be infected with gonorrhea (5.0% vs. 2.6%, AOR 1.9, 95% CI 1.1 to 3.3, p = 0.02). By the follow-up surveys, significant reductions were seen in the proportions of FSWs reporting violence compared with baseline (IBBA 13.0% vs. 9.0%, AOR 0.7, 95% CI 0.5 to 0.9 p = 0.01; PBS 27.3% vs. 18.9%, crude OR 0.5, 95% CI 0.4 to 0.5, p < 0.001). CONCLUSIONS: This program demonstrates that a structural approach to addressing violence can be effectively delivered at scale. Addressing violence against FSWs is important for the success of HIV prevention programs, and for protecting their basic human rights

Regional cerebral metabolic patterns demonstrate the role of anterior forebrain mesocircuit dysfunction in the severely injured brain

peer reviewedAlthough disorders of consciousness (DOCs) demonstrate widely varying clinical presentations and patterns of structural injury, global down-regulation and bilateral reductions in metabolism of the thalamus and frontoparietal network are consistent findings. We test the hypothesis that global reductions of background synaptic activity in DOCs will associate with changes in the pattern of metabolic activity in the central thalamus and globus pallidus. We compared 32 [18F]fluorodeoxyglucose PETs obtained from severely brain-injured patients (BIs) and 10 normal volunteers (NVs). We defined components of the anterior forebrain mesocircuit on high-resolution T1-MRI (ventral, associative, and sensorimotor striatum; globus pallidus; central thalamus and noncentral thalamus). Metabolic profiles for BI and NV demonstrated distinct changes in the pattern of uptake: ventral and association striatum (but not sensorimotor) were significantly reduced relative to global mean uptake after BI; a relative increase in globus pallidus metabolism was evident in BI subjects who also showed a relative reduction of metabolism in the central thalamus. The reversal of globus pallidus and central thalamus profiles across BIs and NVs supports the mesocircuit hypothesis that broad functional (or anatomic) deafferentation may combine to reduce central thalamus activity and release globus pallidus activity in DOCs. In addition, BI subjects showed broad frontoparietal metabolic down-regulation consistent with prior studies supporting the link between central thalamic/pallidal metabolism and down-regulation of the frontoparietal network. Recovery of left hemisphere frontoparietal metabolic activity was further associated with command following

Vulnerability re-assessed: the changing face of sex work in Guntur district, Andhra Pradesh.

We conducted a qualitative study to examine the impact of an HIV prevention programme on female sex workers' lives in Guntur district, Andhra Pradesh. The study found evidence that, in addition to the HIV prevention programme, structural and environmental factors had recently changed the way sex work was being practiced. Recent closure of the brothels and implementation of a late-night street curfew by the police meant sex work had become more hidden, with clients often solicited using mobile phones from home or their work place (e.g., in the fields or factories). Sex work had become safer, with violence by non-regular partners rarely reported. Women understood the risks of unprotected vaginal sex and reported using condoms with their clients. However, clients were more frequently requesting anal sex, possibly due to recent exposure to pornography following increased accessibility to modern technologies such as mobile phones and the Internet. Anal sex with clients was common but women were often unaware of the associated risks and reported unprotected anal sex. HIV positive and/or older women faced severe financial hardship and difficulty soliciting sufficient clients, and reported unprotected vaginal and anal sex to earn enough to survive. Taken together, the findings from this study suggest changing vulnerability to HIV in this setting. It will be important for HIV prevention programmes to be flexible and creative in their approaches if they are to continue to reach this target community effectively

Imaging of Alkaline Phosphatase Activity in Bone Tissue

The purpose of this study was to develop a paradigm for quantitative molecular imaging of bone cell activity. We hypothesized the feasibility of non-invasive imaging of the osteoblast enzyme alkaline phosphatase (ALP) using a small imaging molecule in combination with 19Flourine magnetic resonance spectroscopic imaging (19FMRSI). 6, 8-difluoro-4-methylumbelliferyl phosphate (DiFMUP), a fluorinated ALP substrate that is activatable to a fluorescent hydrolysis product was utilized as a prototype small imaging molecule. The molecular structure of DiFMUP includes two Fluorine atoms adjacent to a phosphate group allowing it and its hydrolysis product to be distinguished using 19Fluorine magnetic resonance spectroscopy (19FMRS) and 19FMRSI. ALP-mediated hydrolysis of DiFMUP was tested on osteoblastic cells and bone tissue, using serial measurements of fluorescence activity. Extracellular activation of DiFMUP on ALP-positive mouse bone precursor cells was observed. Concurringly, DiFMUP was also activated on bone derived from rat tibia. Marked inhibition of the cell and tissue activation of DiFMUP was detected after the addition of the ALP inhibitor levamisole. 19FMRS and 19FMRSI were applied for the non-invasive measurement of DiFMUP hydrolysis. 19FMRS revealed a two-peak spectrum representing DiFMUP with an associated chemical shift for the hydrolysis product. Activation of DiFMUP by ALP yielded a characteristic pharmacokinetic profile, which was quantifiable using non-localized 19FMRS and enabled the development of a pharmacokinetic model of ALP activity. Application of 19FMRSI facilitated anatomically accurate, non-invasive imaging of ALP concentration and activity in rat bone. Thus, 19FMRSI represents a promising approach for the quantitative imaging of bone cell activity during bone formation with potential for both preclinical and clinical applications

Changes in HIV and syphilis prevalence among female sex workers from three serial cross-sectional surveys in Karnataka state, South India.

OBJECTIVES: This paper examined trends over time in condom use, and the prevalences of HIV and syphilis, among female sex workers (FSWs) in South India. DESIGN: Data from three rounds of cross-sectional surveys were analysed, with HIV and high-titre syphilis prevalence as outcome variables. Multivariable analysis was applied to examine changes in prevalence over time. SETTING: Five districts in Karnataka state, India. PARTICIPANTS: 7015 FSWs were interviewed over three rounds of surveys (round 1=2277; round 2=2387 and round 3=2351). Women who reported selling sex in exchange for money or gifts in the past month, and aged between 18 and 49 years, were included. INTERVENTIONS: The surveys were conducted to monitor a targeted HIV prevention programme during 2004-2012. The main interventions included peer-led community outreach, services for the treatment and prevention of sexually transmitted infections, and empowering FSWs through community mobilisation. RESULTS: HIV prevalence declined significantly from rounds 1 to 3, from 19.6% to 10.8% (adjusted OR (AOR)=0.48, p<0.001); high-titre syphilis prevalence declined from 5.9% to 2.4% (AOR=0.50, p<0.001). Reductions were observed in most substrata of FSWs, although reductions among new sex workers, and those soliciting clients using mobile phones or from home, were not statistically significant. Condom use 'always' with occasional clients increased from 73% to 91% (AOR=1.9, p<0.001), with repeat clients from 52% to 86% (AOR=5.0, p<0.001) and with regular partners from 12% to 30% (AOR=4.2, p<0.001). Increased condom use was associated with exposure to the programme. However, condom use with regular partners remained low. CONCLUSIONS: The prevalences of HIV infection and high-titre syphilis among FSWs have steadily declined with increased condom use. Further reductions in prevalence will require intensification of prevention efforts for new FSWs and those soliciting clients using mobile phones or from home, as well as increasing condom use in the context of regular partnerships

Surface science and stability of networks prepared from hydroxy-terminated polydimethylsiloxane and methyltriethoxysilane

Polydimethylsiloxane (PDMS) hybrid networks have been prepared by the reaction of PDMS(OH) 2 , average molecular weight 26 14× 1410 3 , 43.6 14× 1410 3 and 58 14× 1410 3 , and methyltriethoxysilane (MeTEOS, 10–60 wt%) using a dibutyltin dilaurate or dibutyltin diacetate catalyst. By hydrolysis and homo- and co-condensation, MeTEOS forms a siliceous domain (MeSD) and acts as a crosslinker for the PDMS domain. Kinetic studies showed that high MeTEOS and catalyst concentrations and reduction of free surface area favor fast gelation and efficiency in converting MeTEOS to the MeSD. Under the water-sparse conditions utilized, cure was slow and substantial evaporative loss of MeTEOS occurred. © 1998 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38313/1/784_ftp.pd

Quantum saturation and condensation of excitons in Cu2_2O: a theoretical study

Recent experiments on high density excitons in Cu$_2$O provide evidence for degenerate quantum statistics and Bose-Einstein condensation of this nearly ideal gas. We model the time dependence of this bosonic system including exciton decay mechanisms, energy exchange with phonons, and interconversion between ortho (triplet-state) and para (singlet-state) excitons, using parameters for the excitonic decay, the coupling to acoustic and low-lying optical phonons, Auger recombination, and ortho-para interconversion derived from experiment. The single adjustable parameter in our model is the optical-phonon cooling rate for Auger and laser-produced hot excitons. We show that the orthoexcitons move along the phase boundary without crossing it (i.e., exhibit a ``quantum saturation''), as a consequence of the balance of entropy changes due to cooling of excitons by phonons and heating by the non-radiative Auger two-exciton recombination process. The Auger annihilation rate for para-para collisions is much smaller than that for ortho-para and ortho-ortho collisions, explaining why, under the given experimental conditions, the paraexcitons condense while the orthoexcitons fail to do so.Comment: Revised to improve clarity and physical content 18 pages, revtex, figures available from G. Kavoulakis, Physics Department, University of Illinois, Urban