Conventional Ultrafiltration During Elective Cardiac Surgery and Postoperative Acute Kidney Injury

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Fluorimetric determination of activity and isoenzyme composition of N-acetyl-beta-D-hexosaminidase in seminal plasma of fertile men and infertile patients with secretory azoospermia.

BACKGROUND: The activity and isoenzyme composition of N-acetyl-beta-D-hexosaminidase (EC.3.2.1.52) in seminal plasma of fertile and infertile men have been evaluated. However, no data are available on the isoenzyme content in seminal plasma from patients with secretory azoospermia. METHODS: The activity and isoenzyme composition of seminal plasma from 15 normozoospermic controls and 18 patients with secretory azoospermia were determined by fluorimetric methods. 4-Methylumbelliferil-2-acetamido-2-deoxy-beta-D-glucopyranoside and 4-methylumbelliferil-2-acetamido-2-deoxy-beta-D-glucopyranoside-6-sulfate were used as fluorigenic substrates. Receiver-operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficiency of the assays. RESULTS: No significant difference was found in total enzyme activity between the two groups, while isoenzyme A activity was significantly lower (p=0.004) and the ratio between total enzyme activity and isoenzyme A activity was significantly higher (p=0.04) in azoospermic patients compared to controls. The diagnostic efficiency of these evaluations was low (< or =75.7%). CONCLUSIONS: Our findings show that the isoenzyme composition of N-acetyl-beta-D-hexosaminidase in seminal plasma from patients with secretory azoospermia is significantly different from controls, but this difference does not represent a useful marker of secretory azoospermia. The fluorimetric assays are simple and rapid methods for evaluating the isoenzyme composition.     

Quantification of perfusion fMRI using a numerical model of arterial spin labeling that accounts for dynamic transit time effects.

A new approach to modeling the signal observed in arterial spin labeling (ASL) experiments during changing perfusion conditions is presented in this article. The new model uses numerical methods to extend first-order kinetic principles to include the changes in arrival time of the arterial tag that occur during neuronal activation. Estimation of the perfusion function from the ASL signal using this model is also demonstrated. The estimation algorithm uses a roughness penalty as well as prior information. The approach is demonstrated in numerical simulations and human experiments. The approach presented here is particularly suitable for fast ASL acquisition schemes, such as turbo continuous ASL (Turbo-CASL), which allows subtraction pairs to be acquired in less than 3 s but is sensitive to arrival time changes. This modeling approach can also be extended to other acquisition schemes.     

Protein nutrition and amino acid metabolism after 4 weeks of total parenteral nutrition with a mixture of 14 dipeptides: serendipitous observations on effects of sepsis in baboons

We investigated parameters of nutrition, metabolism, and organ function after 4 wk of total parenteral nutrition (TPN) in baboons receiving either dipeptides or amino acids as the nitrogen source. The two groups showed no significant difference with respect to gain in body weight, nitrogen balance, plasma and muscle concentrations of amino acids, plasma concentrations of proteins, and leucine incorporation into muscle protein. All dipeptides were efficiently utilized as evidenced by trace concentrations of dipeptides in plasma and urine; they produced no deleterious effect on the function of liver, kidney, or immune system. Development of infection in several baboons increased urinary excretion of urea nitrogen but had no effect on urinary excretion of dipeptides and amino acids with the single exception of taurine, which was greatly increased. In conclusion, the data show long-term efficacy and safety of the dipeptide mixture as the sole nitrogen source for TPN.