1,720,996 research outputs found

    Renal metabolism of C-peptide in patients with early insulin-dependent diabetes mellitus

    No full text
    Renal metabolism of C-peptide was studied in 6 patients with early insulin-dependent diabetes mellitus (IDDM) with residual beta cell activity and in 11 nondiabetic subjects by the arterial-venous difference technique both in the postabsorptive state and for 80 min after ingestion of an amino acid mixture (0.8 g/kg). Urinary C-peptide (Cp) excretion, glomerular filtration rate and renal plasma flow were also measured. In the postabsorptive state in IDDM, renal uptake of Cp is reduced, while its urinary excretion and clearance are significantly increased. As a result, net renal extraction is markedly reduced. In contrast to controls, renal uptake and net extraction of C-peptide after amino acid ingestion do not increase in patients; the peritubular uptake evident in normal subjects is not detectable. Urinary excretion and clearance of Cp remain significantly higher in IDDM patients. In both groups, renal uptake of C-peptide is directly related to its renal load: however, in IDDM, the increase in Cp uptake for each increment in renal load is 35% lower than in controls (p < 0.001). Furthermore, as opposed to controls, urinary Cp excretion is not correlated with its arterial levels. Therefore IDDM patients have marked defects in renal handling of endogenous Cp, regarding both the amount metabolized by renal tissue and that reabsorbed by tubular cells. These data indicate an early alteration in the diabetic kidney that also impairs the reliability of urinary Cp evaluation as an index of residual beta cell activity in IDDM patients

    Going Beyond Counting First Authors in Author Co-citation Analysis

    Full text link
    The present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed

    Renal metabolism of amino acids in early insulin-dependent diabetes mellitus

    No full text
    Renal metabolism of amino acids (AAs) was evaluated in 5 patients with early IDDM, and in 7 controls (C) in the basal state for 80 minutes after the ingestion of an AA mixture simulating an animal protein meal. Insulin was withdrawn 20 hours before the study. Renal metabolism of AAs was evaluated by the arterial-venous difference technique. In the basal state in IDDM, as in C, the kidney takes up large amounts of a few nonessential AAs (NEAAs): it releases many NEAAs and a few essential AAs (EAAs). After AA ingestion in C, renal extraction of most EAAs, mainly BCAAs, Lys, and Thr, occurs; Pro extraction also increases and a significant uptake of Gly, Glu, Asp, Orn, and Tyr takes place. EAA extraction accounts for 30-40% of total AA uptake. In IDDM, after AA ingestion, a) renal uptake of total AAs is significantly lower, owing mainly to a markedly lower uptake of BCAAs, Lys, and also of Pro, Orn, and Ala; b) renal EAA uptake accounts for less than 20% of total AA extraction. These results indicate that in IDDM postprandial renal N repletion is impaired and unbalanced
    corecore