Centrifugal gradients of rate and organization in human atrial fibrillation.

Introduction: Animal studies show that atrial fibrillation (AF) may emanate from sites of high rate and regularity, with fibrillatory conduction to adjacent areas. We used simultaneous mapping to find evidence for potential drivers in human AF defined as sites with higher rate and regularity than surrounding tissue.

Materials And Methods: In 24 patients (age 61+/-10 years; 12 persistent), we recorded AF simultaneously from 32 left atrial bipolar basket electrodes in addition to pulmonary veins (PV), coronary sinus, and right atrial electrodes.

Adenosine receptors and the kidney.

The autacoid, adenosine, is present in the normoxic kidney and generated in the cytosol as well as at extracellular sites. The rate of adenosine formation is enhanced when the rate of ATP hydrolysis prevails over the rate of ATP synthesis during increased tubular transport work or during oxygen deficiency. Extracellular adenosine acts on adenosine receptor subtypes (A(1), A(2A), A(2B), and A(3)) in the cell membranes to affect vascular and tubular functions.

Serum insulin-like growth factor binding protein-1 levels and bone mineral density in older adults: the Rancho Bernardo Study.

Insulin-like growth factor-I (IGF-I) stimulates osteoblast function, inhibits collagen matrix degradation, and is positively associated with bone mineral density in most but not all studies. We previously reported that IGF-I was positively associated with BMD at the spine and hip in women but not men. Insulin-like growth factor binding protein-1 (IGFBP-1), a potent modulator of IGF-I, is expressed in normal osteoblasts and inhibits collagen gene expression in bone, but little is known about the relationship between IGFBP-1 and bone mineral density (BMD).

fMRI evidence of compensatory mechanisms in older adults at genetic risk for Alzheimer disease.

Objective: To determine whether APOE genotype influences brain response and whether nonverbal stimuli generate findings comparable with those of previous studies that used verbal stimuli. The relationship between APOE genotype and blood oxygenation level dependent (BOLD) brain response was examined during a picture-encoding task in nondemented older adults.

Methods: Twenty nondemented participants with normal episodic memory function were divided into two groups based on the presence (n = 10) or absence (n = 10) of the APOE epsilon4 allele.

A collaborative model for research on decisional capacity and informed consent in older patients with schizophrenia: bioethics unit of a geriatric psychiatry intervention research center.

Rationale: The numbers of older persons with psychiatric disorders are expected to rise rapidly in coming decades, yet most studies of the safety and efficacy of treatments for such disorders have focused on younger adults. A substantial expansion in research involving older patients is needed to meet the treatment needs of this fast growing group. A critical issue in intervention research is ensuring a patient's decision-making capacity.

Social phobia: prevalence and diagnostic threshold.

This article reviews the literature on the prevalence and demographic features of social phobia in both community and general medical settings. The age at onset of social phobia is examined, as are comorbid conditions. Important differences between social phobia as it appears in the community and in primary care settings are explored.

Proteoglycans and cutaneous vascular defense and repair.

Proteoglycans are hybrid molecules composed of a core protein and covalently attached glycosaminoglycan chain(s). The structure, location, and processing of these molecules enables them to encode specific information that is used in multiple physiologic processes. Endothelial cells in the skin are influenced by proteoglycans through binding interactions between glycosaminoglycans and extracellular matrix, growth factors, cytokines, adhesion receptors, enzymes, and enzyme inhibitors.