1,207 research outputs found
Persistent Pleasures: Agency, Social Power, and Embodiment in Women\u27s Solitary Masturbation Experiences
Though sexuality has historically been a useful site for examinations of social power, looking at power through the lens of sexuality often involves interpersonal analyses. But social power can also inform solitary experiences through the internalization of social norms and discourses. In this dissertation, I move beyond explorations of how people interact sexually with one another, and instead investigate womenās solitary masturbation experiences throughout their lives as a means to better understand the intricate ways in which sexist, racist, and heterosexist ideologies weave themselves into womenās bodies and lives. Specifically, I ask the following research question in this dissertation: How (in what ways and by what means) do social power and embodied knowledge interact to inform womenās solitary masturbation experiences?
I conducted semi-structured interviews with thirty adult women (Mean age = 30) in which I asked women to tell me stories about their solitary masturbation experiences throughout their lives. Because solitary masturbation is an activity that women may engage in without ever needing to put language to their experiences, participants first completed a card-sorting task, in which they sorted a stack of cards, each with one statement about womenās masturbation on it, into a distribution that ranged from āmost disagreeā to āmost agree.ā This procedure had the dual purpose of providing participants with examples of language used to discuss masturbation to aid in their articulation of their experiences, and also of giving participants āpermissionā to think about the topic in whatever way felt right to them. After completing the sorting task, I conducted semi-structured interviews with participants. Following transcription of the audio-recorded interviews, I used a combination of thematic and narrative analyses to examine my research question.
Women talked about their solitary masturbation experiences in ways that illuminate the complicated braiding of oppressive social discourses, embodied sensations, and willful subjectivities. Though many women talked about experiences of confusion, shame, and silencing, they also often explicitly rejected negative messages about masturbation, and endeavored to learn more about their bodies and their pleasures. Some women described solitary masturbation experiences in childhood that appeared to have taken place before the participant knew that her activity had a name and a social meaning. These experiences sound very different from those participants talked about happening later in life, in that these childhood experiences seem not to be informed by social discourses ā they appear to be extra-discursive experiences. Those who narrated these experiences also described various ways in which they entered into language and discourse, including sudden realizations (e.g., āOh, thatās what Iāve been doing!ā) and more gradual ones, but in both cases, participants came to recognize their behavior as sexual and laden with social meanings. I found that alongside the traditional feminist project of including womenās experiences within language as a means to political liberation, language can play a different role; as seemed to be the case in womenās childhood extra-discursive masturbation experiences, sometimes a lack of language can provide people with the cognitive space to explore an experience without the constraints of discourse. I also found that even though women may masturbate in physical isolation, relational others are never far beneath the surface of their psyches, and women may be socially expected to concern themselves with relational others even regarding their solitary eroticism (and this pattern holds true both for queer and heterosexual women). Perhaps most importantly, my findings suggest that women are often agentic and determined explorers of their own bodies and experiences; even in the midst of social stigma, women consistently maintain their curiosity, and listen to the embodied wisdom within
NANOCRYSTALS OF CHEMOTHERAPEUTIC AGENTS FOR CANCER THERANOSTICS: DEVELOPMENT AND IN VITRO AND IN VIVO EVALUATION
The majority of pharmacologically active chemotherapeutics are poorly water soluble. Solubilization enhancement by the utilization of organic solvents often leads to adverse side effects. Nanoparticle-based cancer therapy, which is passively targeted to the tumor tissue via the enhanced permeation and retention effect, has been vastly developed in recent years. Nanocrystals, which exist as crystalline and carry nearly 100% drug loading, has been explored for delivering antineoplastic agents. Additionally, the hybrid nanocrystal concept offers a novel and simple way to integrate imaging agents into the drug crystals, enabling the achievement of theranostics. The overall objective of this dissertation is to formulate both pure and hybrid nanocrystals, evaluate their performance in vitro and in vivo, and investigate the extent of tissue distribution and tumor accumulation in a murine model. Pure and hybrid nanocrystals of several model drugs, including paclitaxel (PTX), camptothecin, and ZSTK474, were precipitated by the antisolvent method in the absence of stabilizer, and their size was further minimized by homogenization. The nanocrystals of PTX, which is the focus of the study, had particle size of approximately 200 nm and close-to-neutral surface charge. Depending on the cell type, PTX nanocrystals exerted different level of cytotoxicity. In human colon and breast cancer xenograft models, nanocrystals yielded similar efficacy as the conventional formulation, Taxol, at a dose of 20 mg/kg, yet induced a reduced toxicity. Biodistribution study revealed that 3H-PTX nanocrystals were sequestered rapidly by the macrophages upon intravenous injection. Yet, apparent toxicity was not observed even after four weekly injections. The sequestered nanocrystals were postulated to be released slowly into the blood circulation and reached the tumor. Tritium-labeled-taxol, in contrast, was distributed extensively to all the major organs, inducing systemic toxicity as observed in significant body weight loss. The biodistribution results obtained from radioactive analysis and whole-body optical imaging was compared. To some degree, the correlation was present, but divergence in the quantitative result, due to nanocrystal integrity and limitations associated with the optical modality, existed. Despite their promising properties, nanocrystal suspensions must be securely stabilized by stealth polymers in order to minimize opsonization, extend blood-circulation time, and efficiently target the tumor
Atypical presentation of neuronal ceroid lipofuscinosis type 8 in a sibling pair and review of the eye findings and neurological features.
Purpose:To report atypical presentation of neuronal ceroid lipofuscinoses type 8 (CLN8) to the eye clinic and review clinical features of CLN8. Observations:Detailed eye exam by slit lamp exam, indirect ophthalmoscopy, fundus photography, optical coherence tomography, visual fields and electroretinogram (ERG). Molecular genetic testing using Next Generation Sequencing panel (NGS) and array Comparative Genomic Hybridization (aCGH).The siblings in this study presented to the eye clinic with retinitis pigmentosa and cystoid macular edema, and a history of seizures but no severe neurocognitive deficits or regression. Genetic testing identified a c.200CĀ >Ā T (p.A67V) variant in the CLN8 gene and a deletion encompassing the entire gene. Electron microscopy of lymphocytes revealed fingerprint inclusions in both siblings. Conclusions:and Importance: Pathogenic variants in CLN8 account for the retinitis pigmentosa and seizures in our patients however, currently, they do not have regression or neurocognitive decline. The presentation of NCL can be very diverse and it is important for ophthalmologists to consider this in the differential diagnosis of retinal disorders with seizures or other neurological features. Molecular genetic testing of multiple genes causing isolated and syndromic eye disorders using NGS panels and aCGH along with additional complementary testing may often be required to arrive at a definitive diagnosis
Liposomal daunorubicin as treatment for Kaposiās sarcoma
Anthracycline compounds including daunorubicin are the foundation of many modern chemotherapeutic regimens. However, the side-effects of these compounds can be severe, leading to alopecia, nausea, immune deficiency, and cardiotoxicity. For immunocompromised patients with aggressive Kaposiās sarcoma (KS), these complications often preclude the completion of appropriate chemotherapeutic regimens. This review focuses on the development and efficacy of liposomal daunorubicin (DaunoXomeĀ®; DNX) carriers for the treatment of KS. Encouragingly, DNX demonstrated increased in vivo stability and specificity. As a result, KS patients benefit from higher cumulative chemotherapeutic doses without significant cardiotoxicity. Tumor response to DNX treatment surpasses that of non-encapsulated daunorubicin and is similar to that observed with conventional multi-drug therapies such as ABV (doxorubicin, bleomycin, vincristine). Moreover, some reports indicate the patient quality of life during therapy may improve with DNX treatment. Although the development of DNX represents a significant advance in KS therapy, recent data suggest that additional modification of the liposomal carrier to include pegylation or target specific antibodies may further increase daunorubicin efficacy in the future
Kinetic modifications of C4 PEPC are qualitatively convergent, but larger in Panicum than in Flaveria
C4 photosynthesis results from a set of anatomical features and biochemical components that act together to concentrate CO2 within the leaf and boost productivity. This complex trait evolved independently many times, resulting in various realizations of the phenotype, but in all C4 plants the primary fixation of atmospheric carbon is catalyzed by phosphoenolpyruvate carboxylase. Comparisons of C4 and non-C4 PEPC from a few closely related species suggested that the enzyme was modified to meet the demands of the C4 cycle. However, very few C4 groups have been investigated, hampering general conclusions. To test the hypothesis that distant C4 lineages underwent convergent biochemical changes, we compare the kinetic variation between C4 and non-C4 PEPC from a previously assessed young lineage (Flaveria, Asteraceae) with those from an older lineage found within the distantly related grass family (Panicum). Despite the evolutionary distance, the kinetic changes between the non-C4 and C4 PEPC are qualitatively similar, with a decrease in sensitivity for inhibitors, an increased specificity (kcat/Km) for bicarbonate, and a decreased specificity (kcat/Km) for PEP. The differences are more pronounced in the older lineage Panicum, which might indicate that optimization of PEPC for the C4 context increases with evolutionary time
A combined NMR crystallographic and PXRD investigation of the structure-directing role of water molecules in orotic acid and its lithium and magnesium salts
Despite the abundance of hydrates, their multifaceted nature and hydration/dehydration behaviour is still not fully understood. For the example of orotic acid monohydrate and its lithium and magnesium hydrate salts, we show how NMR crystallography, namely a combination of solid-state NMR with a focus here on 1H Magic Angle Spinning (MAS) NMR experiments and first-principles DFT GIPAW (gauge-including projector augmented wave) calculations, can play a valuable role in the characterization of hydrate systems. Starting from lithium orotate monohydrate, a rigid system with a limited number of tightly bound water molecules, the general feasibility of this approach was demonstrated. Moving onto more complex hydrate structures, mobility in the orotic acid monohydrate was observed, while for the most complex hydrate, magnesium orotate octahydrate, a loss of associated water molecules was observed after an overnight MAS NMR experiment. A combined study by experimental MAS NMR, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) revealed changes after vacuum drying as well as after storage of a vacuum dried sample under ambient conditions. Specifically, TGA showed the vacuum dried sample to correspond to a dihydrate, for which no structure has yet been determined by single-crystal diffraction. An NMR crystallography analysis showed that a combination of putative symmetric and asymmetric dihydrate structures explains the observed changes in the experimental MAS NMR spectra
Molecular phylogenies disprove a hypothesized C4 reversion in Eragrostis walteri (Poaceae)
Background and Aims The main assemblage of the grass subfamily Chloridoideae is the largest known clade of C4 plant species, with the notable exception of Eragrostis walteri Pilg., whose leaf anatomy has been described as typical of C3 plants. Eragrostis walteri is therefore classically hypothesized to represent an exceptional example of evolutionary reversion from C4 to C3 photosynthesis. Here this hypothesis is tested by verifying the photosynthetic type of E. walteri and its classification. Methods Carbon isotope analyses were used to determine the photosynthetic pathway of several E. walteri accessions, and phylogenetic analyses of plastid rbcL and ndhF and nuclear internal transcribed spacer DNA sequences were used to establish the phylogenetic position of the species. Results Carbon isotope analyses confirmed that E. walteri is a C3 plant. However, phylogenetic analyses demonstrate that this species has been misclassified, showing that E. walteri is positioned outside Chloridoideae in Arundinoideae, a subfamily comprised entirely of C3 species. Conclusions The long-standing hypothesis of C4 to C3 reversion in E. walteri is rejected, and the classification of this species needs to be re-evaluate
Stability-activity tradeoffs constrain the adaptive evolution of RubisCO
A well-known case of evolutionary adaptation is that of ribulose-1,5-bisphosphate carboxylase (RubisCO), the enzyme responsible for fixation of CO2 during photosynthesis. Although the majority of plants use the ancestral C3 photosynthetic pathway, many flowering plants have evolved a derived pathway named C4 photosynthesis. The latter concentrates CO2, and C4 RubisCOs consequently have lower specificity for, and faster turnover of, CO2. The C4 forms result from convergent evolution in multiple clades, with substitutions at a small number of sites under positive selection. To understand the physical constraints on these evolutionary changes, we reconstructed in silico ancestral sequences and 3D structures of RubisCO from a large group of related C3 and C4 species. We were able to precisely track their past evolutionary trajectories, identify mutations on each branch of the phylogeny, and evaluate their stability effect. We show that RubisCO evolution has been constrained by stability-activity tradeoffs similar in character to those previously identified in laboratory-based experiments. The C4 properties require a subset of several ancestral destabilizing mutations, which from their location in the structure are inferred to mainly be involved in enhancing conformational flexibility of the open-closed transition in the catalytic cycle. These mutations are near, but not in, the active site or at intersubunit interfaces. The C3 to C4 transition is preceded by a sustained period in which stability of the enzyme is increased, creating the capacity to accept the functionally necessary destabilizing mutations, and is immediately followed by compensatory mutations that restore global stability
Highly expressed genes are preferentially co-opted for C4 photosynthesis
Novel adaptations are generally assembled by co-opting pre-existing genetic components, but the factors dictating the suitability of genes for new functions remain poorly known. In this work, we used comparative transcriptomics to determine the attributes that increased the likelihood of some genes being co-opted for C4 photosynthesis, a convergent complex trait that boosts productivity in tropical conditions. We show that independent lineages of grasses repeatedly co-opted the gene lineages that were the most highly expressed in non-C4 ancestors to produce their C4 pathway. While ancestral abundance in leaves explains which genes were used for the emergence of a C4 pathway, the tissue specificity has surprisingly no effect. Our results suggest that levels of key genes were elevated during the early diversification of grasses and subsequently repeatedly used to trigger a weak C4 cycle via relatively few mutations. The abundance of C4-suitable transcripts therefore facilitated physiological innovation, but the transition to a strong C4 pathway still involved consequent changes in expression levels, leaf specificity, and coding sequences. The direction and amount of changes required for the strong C4 pathway depended on the identity of the genes co-opted, so that ancestral gene expression both facilitates adaptive transitions and constrains subsequent evolutionary trajectories
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