Medicine and Health Sciences Commons^™

Regressing Scalar Outcomes On Image Predictors Via Functional Principal Component Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Simultaneous Confidence Bands For The Coefficient Function In Functional Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Inferring Group Differences In Brain Connectivity From Functional Magnetic Resonance Images, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Reliability Of Functional Connectivity Networks: How Can We Assess It?, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Writing Research Proposal: Literature Review And Database Search, Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

Exaggerated Natriuretic Response Of Brattleboro Rats To Extracellular Volume Expansion, Susan C. Opava-Stitzer, Emma Fernandez-Repollet, Carmen Rodriguez-Sargent, Jose L. Cangiano, Manuel Martinez-Maldonado

Susan C. Opava-Stitzer

A state of chronic dehydration with reduced plasma volume, decreased blood pressure, and increased plasma renin activity (PRA) has been demonstrated in rats with hereditary hypothalamic diabetes insipidus (DI) rats. In this situation decreased renal perfusion and glomerular filtration rate might result in sodium retention. On the other hand, the DI rat also suffers from mineralocorticoid deficiency which might result in salt wasting. In addition it has recently been shown that in contrast to normal rats, there are no differences between superficial cortical and juxtamedullary nephrons of the DI rat with respect to single nephron filtration rate, glomerular volume, and …

Effect Of Potassium On Plasma Renin Concentration In The Presence And Absence Of Adh (Brattleboro Rat Model), Emma Fernandez-Repollet, Susan C. Opava-Stitzer, Manuel Martinez-Maldonado

Susan C. Opava-Stitzer

Rats with hereditary hypothalamic diabetes insipidus (so-called DI rats) have elevated plasma renin levels. Although the mechanism responsible for this condition has not be elucidated, it seems reasonable to postulate that the absence of ADH and/or the hypokalemia previously reported in these rats might contribute to the elevation of plasma renin concentration (PRC). Evidence in favor of this hypothesis emerges from studies in which both ADH and potassium have been shown to inhibit renin release. In an attempt to examine the relative roles of ADH and potassium in the regulation of renin secretion, PRC was measured in DI rats maintained …

Effect Of Lithium And Antidiuretic Hormone On Plasma Renin Concentration In Diabetes Insipidus Rats (Brattleboro Rat Model), Susan C. Opava-Stitzer

Susan C. Opava-Stitzer

Antidiuretic horomone (ADH) is known to inhibit renin secretion in many species, but the mechanism of this inhibition and its importance in the control of renin secretion are unknown.

Evidence For Baroreceptor Control Of Renin Release, Paul C. Churchill, Richard L. Malvin, Susan C. Opava-Stitzer

Susan C. Opava-Stitzer

Arterial plasma renin activity (PRA) was measured using radioimmunoassay techniques in pentobarbital-anesthetized dogs. Acute saline loading (40-60ml 150mm NaCl/kg body weight, or 20ml 300mm NaCl/kg body weight, i.v.) reduced PRA from control level in 7 dogs. Despite continued increases in filtered and excreted masses of Na, subsequent partial aortic clamping increased PRA in proportion to the degree of reduction in renal perfusion pressure. In 6 other dogs aortic clamping super-imposed on total ureteral occlusion led to changes in PRA which were inversely associated with renal perfusion pressure. These results suggest a controlling mechanism for renin secretion sensitive to some hemodynamic …

Urine Concentration And Dilution In The Rat: Contribution Of Papillary Structures During High Rates Of Urine Flow, Manuel Martínez-Maldonado, Susan C. Opava-Stitzer

Susan C. Opava-Stitzer

To examine the contribution of papillary structures to the overall process of urine dilution and concentration at high rates of flow, studies were performed in unilaterally papillectomized kidneys (PX). Comparison of kidney weights in sham-operated and PX rats revealed a significant reduction in total weight of the latter. Papillary length removed was 3045 ± 423 μm. GFR was reduced by 24% and 45% in sham and PX kidneys when compared to their contralateral controls. Under hydropenic conditions, maximal urine concentrating ability (Umax) was comparable in control and sham kidneys but was 59% less in PX kidneys. Fractional sodium excretion during …

Role Of Water Balance In The Enhanced Potassium Excretion And Hypokalaemia Of Rats With Diabetes Insipidus, Emma Fernandez-Repollet, Manuel Martínez-Maldonado, Susan C. Opava-Stitzer

Susan C. Opava-Stitzer

1. The role of water balance in the hypokalaemia of rats with diabetes insipidus (DI rats) was studied. 2. After a 3-day balance study DI rats had a lower muscle potassium content, and plasma [K+], and the urinary excretion of potassium in response to oral KCl loading was reduced when compared to normal rats. The hypokalaemia was found to be associated with elevated concentrations of potassium in renal medulla and papilla when compared to values in normal Long-Evans rats. 3. During a 9-day balance study urinary potassium excretion was higher than that of normal rats on days 1-3, but not …

Pathophysiology Of Clinical Disorders Of Urine Concentration And Dilution, Manuel Martínez-Maldonado, Susan C. Opava-Stitzer

Susan C. Opava-Stitzer

A defect in the ability to concentrate or dilute the urine can be easily recognized by the maximum or minimum urine concentration the patient is able to achieve. Maximum concentrating ability (Umax) is determined by the urine osmolality reached after a fixed period of dehydration and maximal diluting ability (Umin) by the minimum osmolality of the urine after the oral ingestion of a fixed water-load. These indices, however, do not allow an understanding of the pathophysiological alterations leading to the presence of the defect.

Antiepileptic Drugs And Migraine, Michael Rogawski

Michael A. Rogawski

Prepared for the 16th International Headache Research Seminar, “Innovative Drug Development For Headache Disorders,” March 23–25, 2007, Copenhagen, Denmark.

The T-Mixture Model Approach For Detecting Differentially Expressed Genes In Microarrays, Shuo Jiao, Shunpu Zhang

Shuo Jiao

The finite mixture model approach has attracted much attention in analyzing microarray data due to its robustness to the excessive variability which is common in the microarray data. Pan (2003) proposed to use the normal mixture model method (MMM) to estimate the distribution of a test statistic and its null distribution. However, considering the fact that the test statistic is often of t-type, our studies find that the rejection region from MMM is often significantly larger than the correct rejection region, resulting an inflated type I error. This motivates us to propose the t-mixture model (TMM) approach. In this paper, …

Multinomial Logistic Regression: An Application To Estimating Performance Of A Multiple Screening Test For Bowel Cancer When Negatives Are Unverified., Chris Lloyd, Don Frommer

Chris J. Lloyd

This paper describes a method of estimating the performance of a multiple screening test where those who test negative do not have their true disease status determined. The methodology is motivated by a dataset on 49,927 subjects who were given K=6 binary tests for bowel cancer. A complicating factor is that individuals may have polyps present in the bowel, a condition that the screening test is not designed to detect but which may be worth diagnosing. The methodology is based on a multinomial logit model for Pr(S|R_6), the probability distribution of patient status S (healthy, polyps or diseased) conditional on …

Bimanual Coupling In Left And Right Space: Which Hand Is Yoked To Which?, Gavin Buckingham, Gordon Binsted, David Carey

Gavin Buckingham

• Reaching across the body into contralateral space with one hand incurs a substantial cost on various measures of performance, compared to ipsilateral reaches of a similar amplitude (Carey, Hargreaves, & Goodale, 1996).

• When reaching with both hands, unimanual asymmetries disappear.

-The hands take off and land concurrently (Kelso, Southard, & Goodman, 1979).

• To test if this ‘yoking’ is driven by the left or the right hand, participants performed reaches of different amplitudes.

• These reaches were made to the left or right side of space.

-Further increasing the unimanual (baseline) asymmetries that get wiped out by the …

A New Exact And More Powerful Unconditional Test Of No Treatment Effect From Binary Matched Pairs, Chris Lloyd

Chris J. Lloyd

We consider the problem of testing for a difference in the probability of success from matched binary pairs. Starting with three standard inexact tests, the nuisance parameter is first estimated and then the residual dependence is eliminated by maximisation, producing what I call an E+M P-value. The E+M P-value based on McNemar's statistic is shown numerically to dominate previous suggestions, including partially maximised P-values as described in Berger and Sidik (2003). The latter method however may have computational advantages for large samples.

Cellular Effects Of Antiepileptic Drugs, Robert L. Macdonald, Michael A. Rogawski

Michael A. Rogawski

Antiepileptic drugs (AEDs) protect against seizures through interactions with a variety of cellular targets, which include various ion channels, a neurotransmitter transporter, a neurotransmitter metabolic enzyme, and a synaptic vesicle protein. AED actions on these targets can be categorized into four broad groups: 1. Modulation of voltage-dependent ion channels (mainly sodium [Na] but also calcium [Ca] channels) 2. Effects on γ-aminobutyric acid (GABA) systems, including alterations in the cellular disposition of GABA and enhancement of synaptic inhibition mediated by GABA-A receptors 3. Inhibition of synaptic excitation mediated by ionotropic glutamate receptors 4. Modulation of neurotransmitter release, particularly of glutamate, through …

Effect Of Two Milling Techniques And Flours Particle Size On Some, Theodore N'Dede Djeni

Theodore N'Dede Djeni

Two techniques of milling (milling with wooden mortar and milling with hammer grinder) for the production of millet flours were compared in term of physical, biochemical and nutritional aspects and digestibility of the produced flours. A batch of millet grains with candle (Pennisetum glaucum L. R.BR) was purchased from a local market for flour production, while the flour digestibility tests were achieved with an enzymatic crude extract get from gastric juice of and snails (Archachatina marginata). The different rough flours obtained from both milling techniques showed significant differences (p<0.05) in their granulometric profiles and their biochemical composition. The mortar …

Common Pathophysiologic Mechanisms In Migraine And Epilepsy, Michael A. Rogawski

Michael A. Rogawski

Migraine and epilepsy are comorbid episodic disorders that have common pathophysiologic mechanisms. Migraine attacks, like epileptic seizures, may be triggered by excessive neocortical cellular excitability; in migraine, however, the hyperexcitability is believed to transition to cortical spreading depression rather than to the hypersynchronous activity that characterizes seizures. Some forms of epilepsy and migraine are known to be channelopathies. Mutations in the same genes can cause either migraine or epilepsy or, in some cases, both. Given the likely commonalities in the underlying cellular and molecular mechanisms, it is not surprising that some antiepileptic drugs, including valproate, topiramate, and gabapentin, are effective …

Discordance In The Paraoxonase (Pon1)-192qr Polymorphism, Rozaida @ Poh Yuen Ying

Rozaida @ Poh Yuen Ying

Paraoxonase (PON1) has been implicated to have a cardioprotective role, due to its physical attachment with high-density lipoprotein. PON1192QR is a variation of the PON1 gene, the R allele being a risk factor for cardiovascular disease. Kinetic studies resulting in a plot of paraoxon versus diazoxon hydrolysis rates may be used to accurately predict PON1192 geno-type. In this study, paraoxonase and diazoxonase activities in plasma were measured spec-trophotometrically using plasma while PCR-based PON1192 genotyping was performed us-ing polymerase chain reaction followed by restriction digestion. The two-substrate assay-derived genotypes were cross-referred with those determined by PCR-based genotyping. When results did not …

Long-Term Consequences Of The Delay Between Virologic Failure Of Highly Active Antiretroviral Therapy And Regimen Modification, Maya L. Petersen, Mark J. Van Der Laan, Napravnik Sonia, Joseph J. Eron, Richard G. Moore, Steven G. Deeks

Maya Petersen

Objectives: Current treatment guidelines recommend immediate modification of antiretroviral therapy in HIV-infected individuals with incomplete viral suppression. These recommendations have not been tested in observational studies or large randomized trials. We evaluated the consequences of delayed modification following virologic failure. Design/methods: We used prospective data from two clinical cohorts to estimate the effect of time until regimen modification following first regimen failure on all-cause mortality. The impact of regimen type was also assessed. As the effect of delayed switching can be confounded if patients with a poor prognosis modify therapy earlier than those with a good prognosis, we used a …

Functional Generalized Linear Models With Applications To Neuroimaging, Philip T. Reiss, R. Todd Ogden

Philip T. Reiss

No abstract provided.