Publications

The proximal region of the NK gene complex encodes the NKR-P1 family of killer cell lectin-like receptors which in mice bind members of the genetically linked C-type lectin-related family, while the distal region encodes Ly49 receptors for polymorphic MHC class I molecules. Although certain members of the NKR-P1 family are expressed by all NK cells, we have identified a novel inhibitory rat NKR-P1 molecule termed NKR-P1C that is selectively expressed by a Ly49-negative NK subset with unique functional characteristics. NKR-P1C(+) NK cells efficiently lyse certain tumor target cells, secrete cytokines upon stimulation, and functionally recognize a nonpolymorphic ligand on Con A-activated lymphoblasts. However, they specifically fail to kill MHC-mismatched lymphoblast target cells. The NKR-P1C(+) NK cell subset also appears earlier during development and shows a tissue distribution distinct from its complementary Ly49s3(+) subset, which expresses a wide range of Ly49 receptors. These data suggest the existence of two major, functionally distinct populations of rat NK cells possessing very different killer cell lectin-like receptor repertoires.

The native retinal pigment epithelium (RPE) exists as a monolayer structure and is critically involved in the maintenance of photoreceptors. Damage or destruction of the RPE due to a variety of diseases therefore often results in loss of vision. With regenerative purposes in mind, we have examined various culture conditions such as the initial cell density and the addition of various supplements in an effort to produce transplantable RPE cell sheets that can be harvested without defects. We demonstrate that the cell density in cultured RPE sheets increased linearly with the number of seeded cells and that RPE sheets were harvested without defects and limited contraction due to cytoskeletal reorganization, when TGF-beta2 was added to the growth medium. Results from histological analysis and the measurement of trans-epithelial resistance also demonstrates that these RPE cell sheets exist as monolayer structure, similar to the native RPE, with intact cell-to-cell junctions. Therefore, these methods provide significant insight into the fabrication of transplantable RPE cell sheets that can be applied to RPE regenerative therapies to restore lost vision.

Efficient gas exchange in the lungs depends on regulation of the amount of fluid in the thin (average 0.2 mum) liquid layer lining the alveolar epithelium. Fluid fluxes are regulated by ion transport across the alveolar epithelium, which is composed of alveolar type I (TI) and type II (TII) cells. The accepted paradigm has been that TII cells, which cover <5% of the internal surface area of the lung, transport Na(+) and Cl(-) and that TI cells, which cover >95% of the surface area, provide a route for water absorption. Here we present data that TI cells contain functional epithelial Na(+) channels (ENaC), pimozide-sensitive cation channels, K(+) channels, and the cystic fibrosis transmembrane regulator. TII cells contain ENaC and cystic fibrosis transmembrane regulator, but few pimozide-sensitive cation channels. These findings lead to a revised paradigm of ion and water transport in the lung in which (i) Na(+) and Cl(-) transport occurs across the entire alveolar epithelium (TI and TII cells) rather than only across TII cells; and (ii) by virtue of their very large surface area, TI cells are responsible for the bulk of transepithelial Na(+) transport in the lung.

The Study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM), initiated in 2000, investigates the prevalence and correlates of changes in fat distribution, insulin resistance, and dyslipidemia among human immunodeficiency virus (HIV)-infected men and women compared with a population-based group of control men and women. Between June 2000 and September 2002, 1,480 participants (1,183 HIV-infected persons and 297 controls) were enrolled in FRAM. Measurements taken included whole-body magnetic resonance imaging for quantification of regional fat, anthropometric measurements, central laboratory analysis of metabolites, and assessment of symptoms, sociodemographic factors, and lifestyle. Similar measurements were repeated among FRAM participants 4 years later (FRAM 2) for investigation of the progression of fat distribution changes, insulin resistance, and hyperlipidemia. In FRAM 2, which is ongoing, investigators are also determining the associations of subclinical cardiovascular disease, as measured by carotid intimal-medial wall thickness, with HIV infection, fat distribution changes, insulin resistance, and other proatherogenic changes in serum lipid levels. The demographic characteristics of HIV-infected FRAM men and women were comparable to those reported from a national random sampling of HIV-infected men and women receiving medical care in the United States. The representativeness of the FRAM sample increases its value as a resource for studies on fat distribution, metabolic changes, and atherosclerosis in HIV infection.