VA Palo Alto Healthcare System

About: VA Palo Alto Healthcare System is a healthcare organization based out in Palo Alto, California, United States. It is known for research contribution in the topics: Population & Health care. The organization has 2548 authors who have published 4605 publications receiving 209938 citations.

Auditory dysfunction in traumatic brain injury.

Abstract: Effective communication is essential for successful rehabilitation, especially in patients with traumatic brain injury (TBI). The authors examined the prevalence and characteristics of auditory dysfunction in patients with TBI who were admitted to a Department of Veterans Affairs TBI inpatient unit before and after the onset of Operation Iraqi Freedom (OIF). In order to delineate the characteristics of the auditory manifestations of patients who had sustained blast-related (BR) TBI, we reviewed the medical records of 252 patients with TBI and categorized them according to admission date, either before (Group I, n = 102) or after (Group II, n = 150) the onset of OIF. We subdivided Group II into non-blast-related (NBR) and BR TBI; no subjects in Group I had BR TBI. We found that admissions for TBI have increased 47% since the onset of OIF. In Group I, 28% of patients with TBI complained of hearing loss and 11% reported tinnitus. In Group II-NBR (n = 108), 44% complained of hearing loss and 18% reported tinnitus. In Group II-BR (n = 42), 62% complained of hearing loss and 38% reported tinnitus. Sensorineural loss was the most prevalent type of hearing loss in Group II-BR patients. In light of the high prevalence of hearing loss and tinnitus in this growing population of returning soldiers, we need to develop and implement strategies for diagnosis and management of these conditions.

Dose- and time-dependent effects of cyclic hydrostatic pressure on transforming growth factor-beta3-induced chondrogenesis by adult human mesenchymal stem cells in vitro.

Abstract: This study examined effects of varying magnitudes of intermittent hydrostatic pressure (IHP) applied for different times on chondrogenesis of adult human mesenchymal stem cells (hMSCs) in vitro. hMSCs were exposed to 0.1, 1, and 10 MPa of IHP at a frequency of 1 Hz for 4 h/day for 3, 7, and 14 days in the presence of transforming growth factor (TGF-beta3). Chondrogenesis was characterized by gene expression, macromolecule production, and extracellular matrix deposition. Exposure of hMSCs to 0.1 MPa of IHP increased SOX9 and aggrecan mRNA expression by 2.2- and 5.6-fold, respectively, whereas type II collagen mRNA expression responded maximally at 10 MPa. Production of sulfated glycosaminoglycan responded to IHP of 1 MPa and 10 MPa, whereas collagen levels increased only at 10 MPa. Morphologically, matrix condensation occurred with increased IHP, concomitant with collagen expression. This study demonstrated that different levels of IHP differentially modulate hMSC chondrogenesis in the presence of TGF-beta3. The data suggest that tissue engineering of articular cartilage through application or recruitment of hMSCs can be facilitated by mechanical stimulation.

T2 mapping of muscle.

Abstract: Muscle activation produces increases in magnetic resonance ( T(2)) signal intensity leading to recruitment images that demonstrate spatial patterns and intensity of muscle activation. These T(2) activation maps are useful for visualizing and quantifying various aspects of muscle function. Activity-dependent changes in T(2) result from an increase in the T(2) relaxation time of muscle water. The current state of investigation indicates that the mechanism of increased T(2) results from osmotically driven shifts of muscle water that increase the volume of the intracellular space and from intracellular acidification resulting from the end products of metabolism. Although the spatial resolution of magnetic resonance imaging is still insufficient to map territories of individual motor units, it is possible to demonstrate nonuniform activation between subregions or compartments of muscle. Taken together, the attributes of the T(2) mapping technique hold great potential for demonstrating aberrant muscle activation patterns in pathology and positive adaptation to exercise or rehabilitative intervention.