In a systematic review and meta-analysis, Giovanni Musso and colleagues examine the association between non-alcoholic fatty liver disease and chronic kidney disease. Please see later in the article for the Editors' Summary

The CD4 (T4) antigen is a cell-surface glycoprotein that is expressed predominantly on the surface ofhelper T cells and has been implicated in the regulation of T-cell activation and in the associative recognition of class II antigens of the major histocompatibility complex. In addition, the CD4 antigen appears to serve as a receptor for the human immunodeficiency virus (HIV). An important question has been whether the CD4 receptor is linked to an intracellular mediator that could regulate the activation of the CD4+ subset. In this paper, we provide preliminary evidence that the CD4 receptor is complexed in detergent lysates to a protein-tyrosine kinase (PTK) of 55-60 kDa, which is expressed specifically in T cells.The PTK is the human analogue of the murine pp56ISTRA (ppS6Ick) and has significant homology with c-src, c-yes, and other members of the src family. The identification of the PTK associated with CD4 receptor was made by use of an antiserum to a synthetic peptide that was deduced from the DNA sequence of PTK. Two-dimensional nonequilibrium pH gradient gel electrophoresis/NaDodSO4/PAGE revealed the kinase to focus as a heterogeneous collection of spots in the pH range of 4.0-5.0. Furthermore, in vitro phosphorylation revealed the phosphorylation of two additional polypeptides at 40 and 80 kDa, in addition to the autophosphorylation of the PIK at 55-60 kDa.The potential importance of the association between the CD4 receptor and the PTK of T cells is discussed in relation to T-cell activation and HIV infectivity.The CD4 (T4) antigen is a polypeptide of 55 kDa that is expressed predominately on the surface of helper T cells and has been implicated in association with the T3 (CD3)-Ti complex in the recognition of class II antigens of the major histocompatibility complex (1, 2). The CD4 antigen also appears to serve as a receptor for the human immunodeficiency virus (HIV) [the acquired immunodeficiency syndrome (AIDS) virus] (3-5). Structurally, the CD4 antigen is a member of the immunoglobulin superfamily (6) and, as such, appears capable of regulating the proliferation of the CD4 subset of T cells (7)(8)(9)(10)(11). Monoclonal antibodies to the CD4 antigen were initially reported to inhibit specific T-cell function by reducing the strength of interaction of the T cell with its target (1, 2, 7). However, it also appears that monoclonal antibodies to the CD4 receptor can inhibit or potentiate the activation of T lymphocytes in a manner independent of the recognition of HLA-D region antigens (8)(9)(10)(11). The inhibitory effect of antibodies to CD4 appears to preferentially influence the T4+2H4+ subset within the CD4 population, a subset defined by the differential expression of the L-C/T200 (CD45) antigens (12,13 Tyrosine phosphorylation is thought to be a relatively rare modification to proteins; however, the past few years have seen a rapidly expanding number of retroviral oncogenes and cellular receptors within the src family. These include the retroviral oncogenes such as v-abl, v-erb, v-fes/...

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