Hisamitsu Nakahashi

Postoperative hemodynamic and metabolic changes in patients with subarachnoid hemorrhage.

Positron emission tomography was performed using an oxygen-15 gas inhalation technique to measure regional cerebral blood flow, metabolic rate for oxygen, oxygen extraction fraction, and cerebral blood volume in 13 patients with subarachnoid hemorrhage during the period of delayed vasospasm after surgery as well as in 10 volunteers as controls. Compared with the controls, the patients showed decreased hemoglobin concentration and decreased total arterial oxygen content due to postoperative hemodilution. Global reductions in the metabolic rate for oxygen and in the tissue oxygen supply were noted even in the apparently normal cortex of the patients in spite of adequate blood flow and adequate oxygen extraction fraction. In addition, regional reductions in blood flow and in perfusion reserve were seen in the cortical territory corresponding to cerebral vasospasm. Our results indicate that two processes are involved in the pathophysiology of cerebral vasospasm: 1) generalized impairment of oxygen metabolism with a reduced tissue oxygen supply, even in the apparently normal cortex, and 2) additional impairment of regional perfusion in the territory of vasospasm.

Underestimation of serum albumin by the bromcresol purple method and a major endogenous ligand in uremia

In hemodialyzed patients, the serum albumin concentration determined by the bromcresol purple (BCP) method was lower than that determined by an immunological method. The degree of underestimation appeared to be well correlated to the serum concentration of 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), a major endogenous ligand substance present in uremic serum. CMPF inhibited in vitro the binding of BCP to serum protein and human serum albumin. Our results suggest that CMPF is a major interferent in the underestimation of the serum albumin concentration by the BCP method in uremia.

Isolation and Characterization of an Endogenous Drug-Binding Inhibitor Present in Uremic Serum

Isolation of an endogenous ligand solute from uremic serum was performed by high-performance liquid chromatography. This ligand solute inhibited the binding of diphenylhydantoin and tryptophan to plasma protein, and was considered to be one of the endogenous drug-binding inhibitors present in uremic serum. The gas chromatographic-mass spectrometric analysis revealed that this inhibitor is 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid, which is known to be a constituent of urine.

Inhibition of Hepatic Glutathione S-Transferases by a Major Endogenous Ligand Substance Present in Uremic Serum

A major endogenous ligand substance present in uremic serum, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid, inhibited the in vitro activity of bovine and rat liver glutathione S-transferases. Our results suggested that endogenous ligand substances retained in uremic serum have some toxic activities other than the inhibition of drug binding to serum protein observed in uremia.

Difference in regional hepatic blood flow in liver segments--non-invasive measurement of regional hepatic arterial and portal blood flow in human by positron emission tomography with H2(15)O.

Organ blood flow can be quantitatively measured by positron emission tomography (PET). As the liver has dual blood supplies, arterial and portal, regional hepatic blood flow had not been measured quantitatively. However, we succeeded in simultaneously measuring both regional hepatic arterial and portal blood flow by PET in non-stressed patients. Mean regional portal hepatic blood flow in patients with normal liver and cirrhotic liver was 57.5 and 36.7 ml/minutes/100 g, respectively. Mean regional arterial blood flow was 42.5 and 30.7 ml/minutes/100 g, respectively. A significant difference between regional portal hepatic blood flows in normal and cirrhotic patients was noted. Mean regional portal hepatic blood flow in the lateral, medial, anterior, and posterior segments of the liver was 29.8, 43.4, 50.0, and 40.9 ml/minutes/100 g, respectively. Mean regional arterial blood flow in each liver segment was 37.6, 30.0, 28.2, and 31.6 mi/minutes/100 g, respectively. A significant difference between regional portal hepatic blood flows in lateral and anterior segment was noted. The p value was less than 0.025 and the 95 % confidence interval of the difference between means was from −20.2 to −2.7 ml/minutes/100 g by ANOVA. These results showed that regional hepatic blood flow is not the same in all the liver segments.

Profiling of Endogenous Ligand Solutes That Bind to Serum Proteins in Sera of Patients with Uremia

The profiling of endogenous ligand solutes in sera of patients with uremia was performed by using an ultrafiltration device and high-performance liquid chromatography. Seventeen endogenous ligand solutes, which are ultraviolet-absorbing substances, were detected in a sample volume of 40 microliters, and four ligand solutes were tentatively identified as indoxylsulfate, hippuric acid, 2-hydroxybenzoylglycine, and 3-indoleacetic acid. One of these ligand solutes designated as peak P was thought to be a candidate for a major drug-binding inhibitor in uremia.

Displacement by anionic drugs of endogenous ligands bound to albumin in uremic serum

Impaired binding of anionic drugs to serum albumin in patients with uremia is thought to be due to the accumulation of endogenous substances that bind to albumin. In this study the displacement by the anionic drugs diazepam. warfarin, and salicylic acid, which are known to be representative drugs for the binding sites on the albumin molecule, of several endogenous ligands that bind to albumin in uremic serum was examined. The free fractions of the ligands bound to albumin were separated by ultrafiltration in the presence and the absence of test drugs and assayed by high-performance liquid chromatography. Diazepam displaced indoxyl sulfate (IS), hippuric acid (HA), and indole-3-acetic acid (IAA), and warfarin displaced IS. HA. IAA. and 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid from serum albumin. However, salicylic acid did not displace the substance examined. The methods reported here are useful for determining the binding sites of the endogenous ligands on albumin and to clarify the drug-ligand interaction on albumin molecule in uremic serum.

Systematic separation of medium-sized biologically active peptides by high-performance liquid chromatography.

The systematic separation of medium-sized biologically active peptides by high-performance liquid chromatography (HPLC) is described. Three steps are involved: first, high-performance sodium dodecyl sulphate (SDS) gel chromatography on a newly developed column. TSK-GEL 2000SW; secondly, ion-pair reversed-phase HPLC using stepwise elution mobile phases containing SDS and tetrabutylammonium phosphate; thirdly, high-performance cation-exchange chromatography on a Partisil SCX column for purification, using stepwise gradient elution with volatile buffers. Removal of SDS was possible in the final step. This systematic method is fast, reproducible and gives excellent separations and recoveries.

The Effect of Renal Transplantation on a Major Endogenous Ligand Retained in Uremic Serum

The effects of renal transplantation on serum concentrations of 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) and indole-3-acetic acid (IAA), which are endogenous ligands retained in uremic serum, and on phenytoin binding to serum protein were investigated. IAA, a weakly bound ligand, was rapidly excreted by the transplanted kidney during the first one to three days after renal transplantation, but CMPF, a strongly bound ligand, was slowly excreted. The binding defect of phenytoin was partially corrected by transplantation during the period of study. The results suggested that the prolonged drug binding defect observed despite successful renal transplantation is caused by a slower decrease of strongly bound ligands such as CMPF retained in uremic serum; hypoalbuminemia, usually observed after transplantation, may also contribute to this phenomenon.

Profiling of urinary medium-sized peptides in normal and uremic urine by high-performance liquid chromatography

This report describes the profiling of medium-sized peptides in both normal and uremic urine by ion-pair reversed-phase high-performance liquid chromatography using an acetonitrile--heptafluorobutyric acid solvent system as eluent. Several medium-sized peptide peaks could be detected in both normal and uremic urine at low picomole level by using post-column fluorescence derivatization with fluorescamine. Contrary to expectation, uremic urine contained slightly larger amounts of medium-sized peptides compared with normal urine.