AMP-activated protein kinase (AMPK)α2 plays a role in determining the cellular fate of glucose in insulin-resistant mouse skeletal muscle.

AIMS/HYPOTHESIS: We determined whether: (1) an acute lipid infusion impairs skeletal muscle AMP-activated protein kinase (AMPK)α2 activity, increases inducible nitric oxide synthase (iNOS) and causes peripheral insulin resistance in conscious, unstressed, lean mice; and (2) restoration of AMPKα2 activity during the lipid infusion attenuates the increase in iNOS and reverses the defect in insulin sensitivity in vivo. METHODS: Chow-fed, 18-week-old C57BL/6J male mice were surgically catheterised. After 5 days they received: (1) a 5 h infusion of 5 ml kg(-1) h(-1) Intralipid + 6 U/h heparin (Lipid treatment) or saline (Control); (2) Lipid treatment or Control, followed by a 2 h hyperinsulinaemic-euglycaemic clamp (insulin clamp; 4 mU kg(-1) min(-1)); and (3) infusion of the AMPK activator, 5-aminoimidazole-4-carboxamide 1-ß-D-ribofuranoside (AICAR) (1 mg kg(-1) min(-1)), or saline during Lipid treatment, followed by a 2 h insulin clamp. In a separate protocol, mice producing a muscle-specific kinase-dead AMPKα2 subunit (α2-KD) underwent an insulin clamp to determine the role of AMPKα2 in insulin-mediated muscle glucose metabolism. RESULTS: Lipid treatment decreased AMPKα2 activity, increased iNOS abundance/activation and reduced whole-body insulin sensitivity in vivo. AICAR increased AMPKα2 activity twofold; this did not suppress iNOS or improve whole-body or tissue-specific rates of glucose uptake during Lipid treatment. AICAR caused a marked increase in insulin-mediated glycogen synthesis in skeletal muscle. Consistent with this latter result, lean α2-KD mice exhibited impaired insulin-stimulated glycogen synthesis even though muscle glucose uptake was not affected. CONCLUSIONS/INTERPRETATION: Acute induction of insulin resistance via lipid infusion in healthy mice impairs AMPKα2, increases iNOS and causes insulin resistance in vivo. However, these changes do not appear to be interrelated. Rather, a functionally active AMPKα2 subunit is required for insulin-stimulated muscle glycogen synthesis.

Application of TruGraf v1: A Novel Molecular Biomarker for Managing Kidney Transplant Recipients With Stable Renal Function.

TruGraf v1 is a laboratory-developed DNA microarray-based gene expression blood test to enable proactive noninvasive serial assessment of kidney transplant recipients with stable renal function. It has been previously validated in patients identified as Transplant eXcellence (TX: stable serum creatinine, normal biopsy results, indicative of immune quiescence), and not-TX (renal dysfunction and/or rejection on biopsy results). TruGraf v1 is intended for use in subjects with stable renal function to measure the immune status as an alternative to invasive, expensive, and risky surveillance biopsies. MATERIALS AND METHODS: In this study, simultaneous blood tests and clinical assessments were performed in 192 patients from 7 transplant centers to evaluate TruGraf v1. The molecular testing laboratory was blinded to renal function and biopsy results. RESULTS: Overall, TruGraf v1 accuracy (concordance between TruGraf v1 result and clinical and/or histologic assessment) was 74% (142/192), and a result of TX was accurate in 116 of 125 (93%). The negative predictive value for TruGraf v1 was 90%, with a sensitivity 74% and specificity of 73%. Results did not significantly differ in patients with a biopsy-confirmed diagnosis vs those without a biopsy. CONCLUSIONS: TruGraf v1 can potentially support a clinical decision enabling unnecessary surveillance biopsies with high confidence, making it an invaluable addition to the transplant physician's tool kit for managing patients. TruGraf v1 testing can potentially avoid painful and risky invasive biopsies, reduce health care costs, and enable frequent assessment of patients with stable renal function to confirm the presence of immune quiescence in the peripheral blood.

Evaluation of neonatal whole blood versus plasma glucose concentration by ion-selective electrode technology and comparison with two whole blood chromogen test strip methods.

OBJECTIVE: Determination of glucose concentration from whole blood samples in neonates is confounded by variable hematocrit values, sample source, user technique, and test method, which results in poor correlation with glucose values measured from plasma or serum. Recently developed ion-selective electrodes (ISE) allow measurement of glucose in the water phase of both red blood cells and plasma with a small sample size (200 microliters). STUDY DESIGN: The purpose of this study was to compare (1) whole blood and plasma glucose measurements by the ISE method and (2) ISE glucose values with those determined by two chromogen reagent test strip colorimetric methods. Values were determined in 180 different samples obtained from 145 infants. RESULTS: Correlation of whole blood and plasma glucose concentrations determined by the ISE method was excellent (y = 0.99x, R2 = 0.99) and no effect was seen from hematocrit values. The two chromogen test strip methods also revealed good linearity with ISE whole blood and plasma glucose values but had large confidence intervals for individual values. Sensitivity for detecting blood glucose levels < 40 mg/dl by the two test strip methods was 9 of 11 and 9 of 10 with four and one false-positive results, respectively. CONCLUSION: These data indicate that the ISE method provides an excellent correlation of whole blood and plasma glucose measurement results, overcoming technical problems of differing hematocrit values and serum or plasma sample acquisition in neonates. Chromogen test strip methods have limited value in estimating specific glucose values, but can be useful in screening infants for hypoglycemia.

Application of laboratory diagnostics in HIV nursing.

The HIV epidemic has challenged nursing to rethink the tools it uses and to consider how traditional medical tools may be used in the assessment of nursing problems. This article presents information for the direct care nurse on laboratory tests and how they may be used to meet the traditional needs of physiologic assessment and evaluation and to develop specific nursing interventions. This articles discusses tests used for HIV infection, HIV disease progression, presence of microbiologic agents of opportunistic infections commonly associated with advanced HIV disease, and common laboratory tests and their special relevance to HIV. Nursing implications and interventions are discussed throughout the text.

Leukocyte proteinases in wound healing: roles in physiologic and pathologic processes.

Leukocytes express a number of proteinases which play critical roles in physiologic processes during wound healing. However, if the activity of these proteinases is uncontrolled, they can contribute to devastating tissue injury that can affect most organ systems. Until recently, little was known about the mechanisms by which leukocytes retain the activity of their proteinases within the extracellular space which contains highly effective proteinase inhibitors. Studies of the cell biology of leukocyte proteinases have begun to identify the mechanisms by which proteinases can circumvent the effects of physiologic proteinase inhibitors. Herein, we will review the cell biology of leukocyte proteinases, and we will discuss the mechanisms by which leukocyte proteinases can contribute to physiologic processes occurring during wound healing, as well as their roles in pathologic processes.