Surface water-- groundwater interaction : the spatial organization of hydrologic processes over complex terrain

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.Includes bibliographical references (p. 232-242).by Karen Plaut Berger.Ph.D

Unique N170 Signatures to Words and Faces in Deaf ASL Signers Reflect Experience-Specific Adaptations During Early Visual Processing

Previous studies with deaf adults reported reduced N170 waveform asymmetry to visual words, a finding attributed to reduced phonological mapping in left-hemisphere temporal regions compared to hearing adults. An open question remains whether this pattern indeed results from reduced phonological processing or from general neurobiological adaptations in visual processing of deaf individuals. Deaf ASL signers and hearing nonsigners performed a same-different discrimination task with visually presented words, faces, or cars, while scalp EEG time-locked to the onset of the first item in each pair was recorded. For word recognition, the typical left-lateralized N170 in hearing participants and reduced left-sided asymmetry in deaf participants were replicated. The groups did not differ on word discrimination but better orthographic skill was associated with larger N170 in the right hemisphere only for deaf participants. Face recognition was characterized by unique N170 signatures for both groups, and deaf individuals exhibited superior face discrimination performance. Laterality or discrimination performance effects did not generalize to the N170 responses to cars, confirming that deaf signers are not inherently less lateralized in their electrophysiological responses to words and critically, giving support to the phonological mapping hypothesis. P1 was attenuated for deaf participants compared to the hearing, but in both groups, P1 selectively discriminated between highly learned familiar objects – words and faces versus less familiar objects – cars. The distinct electrophysiological signatures to words and faces reflected experience-driven adaptations to words and faces that do not generalize to object recognition

Delayed Lactogenesis II is Associated With Lower Sleep Efficiency and Greater Variation in Nightly Sleep Duration in the Third Trimester

Background: Metabolic and hormonal disturbances are associated with sleep disturbances and delayed onset of lactogenesis II. Research aims: The aim of this study was to measure sleep using wrist actigraphy during gestation weeks 22 and 32 to determine if sleep characteristics were associated with blood glucose, body mass index, gestational related disease, delayed onset of lactogenesis II, or work schedule. Methods: Demographic data were collected at study intake from primiparous women who wore a wrist actigraph during gestation weeks 22 (n = 50) and 32 (n = 44). Start and end sleep time, total nighttime sleep, sleep efficiency, wake after sleep onset, and sleep fragmentation were measured. Night to night variability was assessed with the root mean square of successive difference. Blood glucose levels, body mass index, and gestational disease data were abstracted from medical charts. Timing of lactogenesis II was determined by survey. Results: Between gestation week 22 and 32, sleep efficiency decreased and fragmentation increased (p < .05). During gestation week 32, blood glucose was negatively correlated with sleep duration, and positively related to fragmentation (p < .05). Women who experienced delayed lactogenesis II had lower sleep efficiency and greater fragmentation (p < .05), and greater night-to-night variability in sleep start and end time, efficiency, and duration during gestation week 32 (p < .05). Conclusion: Women with better sleep efficiency and more stable nightly sleep time are less likely to experience delayed onset of lactogenesis II. Interventions to improve sleep may improve maternal health and breastfeeding adequacy

The anterior temporal lobes support residual comprehension in Wernicke’s aphasia

Wernicke’s aphasia occurs following a stroke to classical language comprehension regions in the left temporoparietal cortex. Consequently, auditory-verbal comprehension is significantly impaired in Wernicke’s aphasia but the capacity to comprehend visually presented materials (written words and pictures) is partially spared. This study used fMRI to investigate the neural basis of written word and picture semantic processing in Wernicke’s aphasia, with the wider aim of examining how the semantic system is altered following damage to the classical comprehension regions. Twelve participants with Wernicke’s aphasia and twelve control participants performed semantic animate-inanimate judgements and a visual height judgement baseline task. Whole brain and ROI analysis in Wernicke’s aphasia and control participants found that semantic judgements were underpinned by activation in the ventral and anterior temporal lobes bilaterally. The Wernicke’s aphasia group displayed an “over-activation” in comparison to control participants, indicating that anterior temporal lobe regions become increasingly influential following reduction in posterior semantic resources. Semantic processing of written words in Wernicke’s aphasia was additionally supported by recruitment of the right anterior superior temporal lobe, a region previously associated with recovery from auditory-verbal comprehension impairments. Overall, the results concord with models which indicate that the anterior temporal lobes are crucial for multimodal semantic processing and that these regions may be accessed without support from classic posterior comprehension regions

Transcriptome Analysis of Epithelial and Stromal Contributions to Mammogenesis in Three Week Prepartum Cows

Transcriptome analysis of bovine mammary development has provided insight into regulation of mammogenesis. However, previous studies primarily examined expression of epithelial and stromal tissues combined, and consequently did not account for tissue specific contribution to mammary development. Our objective was to identify differences in gene expression in epithelial and intralobular stromal compartments. Tissue was biopsied from non-lactating dairy cows 3 weeks prepartum, cut into explants and incubated for 2 hr with insulin and hydrocortisone. Epithelial and intralobular stromal tissues were isolated with laser capture microdissection. Global gene expression was measured with Bovine Affymetrix GeneChips, and data were preprocessed using RMA method. Moderated t-tests from gene-specific linear model analysis with cell type as a fixed effect showed more than 3,000 genes were differentially expressed between tissues (P<0.05; FDR<0.17). Analysis of epithelial and stromal transcriptomes using Database for Annotation, Visualization and Integrated Discovery (DAVID) and Ingenuity Pathways Analysis (IPA) showed that epithelial and stromal cells contributed distinct molecular signatures. Epithelial signatures were enriched with gene sets for protein synthesis, metabolism and secretion. Stromal signatures were enriched with genes that encoded molecules important to signaling, extracellular matrix composition and remodeling. Transcriptome differences also showed evidence for paracrine interactions between tissues in stimulation of IGF1 signaling pathway, stromal reaction, angiogenesis, neurogenesis, and immune response. Molecular signatures point to the dynamic role the stroma plays in prepartum mammogenesis and highlight the importance of examining the roles of cell types within the mammary gland when targeting therapies and studying mechanisms that affect milk production

Swim-Training Changes the Spatio-Temporal Dynamics of Skeletogenesis in Zebrafish Larvae (Danio rerio)

Fish larvae experience many environmental challenges during development such as variation in water velocity, food availability and predation. The rapid development of structures involved in feeding, respiration and swimming increases the chance of survival. It has been hypothesized that mechanical loading induced by muscle forces plays a role in prioritizing the development of these structures. Mechanical loading by muscle forces has been shown to affect larval and embryonic bone development in vertebrates, but these investigations were limited to the appendicular skeleton. To explore the role of mechanical load during chondrogenesis and osteogenesis of the cranial, axial and appendicular skeleton, we subjected zebrafish larvae to swim-training, which increases physical exercise levels and presumably also mechanical loads, from 5 until 14 days post fertilization. Here we show that an increased swimming activity accelerated growth, chondrogenesis and osteogenesis during larval development in zebrafish. Interestingly, swim-training accelerated both perichondral and intramembranous ossification. Furthermore, swim-training prioritized the formation of cartilage and bone structures in the head and tail region as well as the formation of elements in the anal and dorsal fins. This suggests that an increased swimming activity prioritized the development of structures which play an important role in swimming and thereby increasing the chance of survival in an environment where water velocity increases. Our study is the first to show that already during early zebrafish larval development, skeletal tissue in the cranial, axial and appendicular skeleton is competent to respond to swim-training due to increased water velocities. It demonstrates that changes in water flow conditions can result into significant spatio-temporal changes in skeletogenesis

Homeorhetic Adaptation During the Pregnancy to Lactation Transition: Role of Solute Transporter Genes in Key Metabolic Tissues

Control of solute transport in the lactating mammary gland in tandem with adjustments in other key metabolic tissues, such as adipose and liver is pivotal, both in supporting milk synthesis and maintaining homeorhesis during lactation. Therefore, the goal of this study was to identify a more comprehensive cohort of solute transporter genes in mammary, liver, and adipose tissue that are transcriptionally controlled during the pregnancy to lactation transition. Total RNA was isolated from mammary, liver and adipose tissues collected from rat dams on day 20 of pregnancy (P20) and day 1 of lactation (L1) and gene expression was measured using Rat 230 2.0 Affymetrix GeneChips. Parametric gene set enrichment analysis method was utilized to identify transcriptional differences between P20 and L1 tissues. The foremost upregulated genes observed in the three tissues included amino-acid transporter, Slc1a2 (7.2 fold, FDR \u3c0.001), nucleoside transporter, Slc28a3 (6.6 fold, FDR \u3c0.001) and Zinc transporter, Slc30a5 (4.4 fold, FDR \u3c0.001) in the mammary; sodium-dependent phosphate transporter, Slc34a2 (11.2 fold, FDR \u3c0.001), sodium- and chloride-dependent GABA transporter, Slc6a1 (3.3 fold, FDR \u3c0.001) and monocarboxylic acid transporter, Slc16a13 (2.1 fold, FDR \u3c0.001) in the liver; sodium/chloride transporter, Slc12a3 (2.4 fold, FDR \u3c0.01), facilitated glucose transporter, Slc2a9 (1.8 fold, FDR \u3c0.05) and fatty acid transporter, Slc27a3 (1.6 fold, FDR \u3c0.05) in the adipose tissue from P20 to L1. The leading downregulated transcripts observed in the three tissues included organic cation transporter, Slc22a17 (-4.3 fold, FDR \u3c0.001), mitochondrial solute transporter, Slc22a17 (-3.4 fold, FDR \u3c0.001) and facilitated glucose transporter, Slc2a8 (-3.0 fold, FDR \u3c0.001) in the mammary; glucose/fructose transporter, Slc2a5 (-2.1 fold, FDR \u3c0.1), sodium/chloride transporter, Slc12a3 (-1.8 fold, FDR \u3c0.01), and mitochondrial transporter, Slc25a42 (-1.8 fold, FDR \u3c0.1) in liver; glucose-6-phosphate transporter, Slc37a4 (-2.6 fold, FDR \u3c0.01), facilitated glucose transporter, Slc2a4 (-2.5 fold, FDR \u3c0.01) and amino acid transporter, Slc1a1 (-1.8 fold, FDR \u3c0.05) in adipose tissue from late pregnancy to early lactation. Our results shows that among the strategies employed by the dam to support the rising demands of homeorhesis during pregnancy to lactation transition is careful orchestration of steady-state expression of solute transporters of various classes among multiple tissues