L-dopa pharmacokinetics studied with microdialysis in patients with Parkinson's disease and a history of malignant melanoma.

OBJECTIVES: The pharmacokinetics of free L-dopa in blood and tissue of five parkinsonian patients with malignant melanoma was studied with microdialysis. In one case the effect of L-dopa treatment on 5-S-cysteinyldopa and the melanoma was studied. Gastric emptying and its effects on free L-dopa in blood were also investigated in one of the patients. METHODS: Five patients were given 100 mg L-dopa with 25 mg benserazide. Blood and dialysates from the circulation and fatty tissue were collected for analysis. [13C]-Octanoic breath test was used for analyzing gastric half-emptying time. RESULTS: Four of the patients had similar pharmacokinetic patterns for L-dopa and a significant (P < 0.05) increase of serum 5-S-cysteinyldopa occurring 30 min after L-dopa intake. Delayed L-dopa peaks and slow gastric half-emptying time were found in 1 patient. A dose-dependent increase of 5-S-cysteinyldopa occurred but no melanoma metastases were seen during long-term L-dopa therapy. CONCLUSION: L-dopa therapy increases 5-S-cysteinyldopa levels but does not seem to cause progress of melanomas. Gastric emptying impacts L-dopa pharmacokinetics.

Different intestinal permeability patterns in relatives and spouses of patients with Crohn's disease: an inherited defect in mucosal defence?

BACKGROUND: A familial defect in intestinal barrier function has been found in Crohn's disease. AIM: To investigate possible genetic and environmental influences on this barrier defect by studying intestinal permeability in both relatives and spouses of patients with Crohn's disease. SUBJECTS: The study included 39 patients with Crohn's disease, 34 healthy first degree relatives, and 22 spouses. Twenty nine healthy volunteers served as controls. METHODS: Intestinal permeability was assessed as the lactulose:mannitol ratio in five hour urinary excretion after oral load, both before (baseline) and after ingestion of acetylsalicylic acid. The permeability response represents the difference between the two tests. A ratio above the 95th percentile for controls was classified as abnormal. RESULTS: Baseline permeability was higher in patients and spouses than in controls. An abnormal baseline permeability was seen in 36% of the patients, 23% of the spouses, 18% of the relatives, and 3% of the controls. After ingestion of acetylsalicylic acid, permeability increased significantly in all groups. Relatives were similar to patients with regard to permeability after exposure to acetylsalicylic acid, whereas spouses were similar to controls. The proportions with an abnormal permeability response to acetylsalicylic acid were 32% in patients, 14% in spouses, 41% in relatives, and 3% in controls. CONCLUSION The findings suggest that baseline permeability is determined by environmental factors, whereas permeability provoked by acetylsalicylic acid is a function of the genetically determined state of the mucosal barrier, and support the notion that environmental and hereditary factors interact in the pathogenesis of Crohn's disease.

Evaluation of the carbon 13-labeled Ketoisocaproate breath test to assess mitochondrial dysfunction in patients with high alcohol consumption.

There are few functional tests for liver function that selectively indicate the toxic effect of alcohol abuse. To explore the long-term impact of excessive alcohol use on the liver, there is a need for such specific analyses. The Ketoisocaproate breath test has been shown to be a specific marker of mitochondrial function in the liver, which is known to be selectively affected by heavy alcohol intake. This method was evaluated by analyzing 13 male patients with severe alcohol dependence and comparing these with 10 healthy volunteers, 5 women and 5 men. All alcoholic patients reported a heavy intake of alcohol during the last month before the test and all had some form of abnormal liver status as assessed by traditional markers such as aspartate aminotransferase, alanine aminotransferase, or gamma-glutamyltransferase analyses. The results showed that healthy women had a higher percentage exhalation of 13CO2 than both healthy males and alcoholic males. In contrast to previous studies, we found no significant impairment of Ketoisocaproate decarboxylation as an effect of chronic intake of alcohol or alcohol-induced steatosis. The findings could not be explained completely by concurrent drug intake used in the routine detoxification of the patients. Thus, the value of the Ketoisocaproate breath test as a biological marker of excessive alcohol consumption appears to be limited because of a fast normalization of the values.

Asymptomatic Helicobacter pylori gastritis is associated with increased sucrose permeability.

Our aim was to investigate whether there are changes in permeability to sucrose in asymptomatic Helicobacter pylori gastritis. Nineteen asymptomatic subjects with Helicobacter pylori-associated gastritis with no or mild mucosal atrophy and 19 age- and sex-matched normal controls were studied by peroral load of sucrose (100 g). The fraction of the given oral dose of sucrose excreted in urine was increased in subjects with Helicobacter pylori gastritis (median 0.08% versus 0.04% in controls). Sucrose excretion was not related to atrophy, intestinal metaplasia, or inflammation in the gastric mucosa. However, sucrose permeability was related to the degree of inflammatory (neutrophil) activity, since moderate activity was associated with higher sucrose excretion than mild activity (median 0.13% vs 0.07%). Asymptomatic Helicobacter pylori gastritis was associated with an increased sucrose permeability, which could be a sign of gastric mucosal leakage. This could have implications for the diseases and complications associated with Helicobacter pylori infection.

Accurate and precise isotope dilution mass spectrometry method for determining glucose in whole blood.

An accurate and precise method to determine glucose concentration in whole blood is presented. The method, based on isotope dilution gas chromatography-mass spectrometry (ID GC-MS), was developed to be used as a Reference Method for determining glucose concentration in capillary or venous whole blood. Blood samples and standards are pipetted manually with "microcap" micropipettes, which makes it possible to collect samples even at the patient's bedside. Glucose is quantified as its aldononitrile pentaacetate. [13C6]Glucose is used as an internal standard. Assay of Seronorm and Pathonorm L and H controls by ID GC-MS gave within-run CVs of 0.66%, 0.96%, and 0.92%, respectively. For whole blood with glucose concentrations in the low, normal, and high ranges, the within-run CVs were 1.27%, 0.91%, and 0.78%, respectively. The between-run CV for glucose calculated from 36 separate single analyses of Seronorm was 1.44%. In an accuracy assessment test of the HemoCue blood glucose analyzer, 140 capillary blood samples were measured in parallel after split-sampling. For all samples the HemoCue analyzer results had a mean bias of +2.0% compared with the ID GC-MS results.

Studies on lipoamidase: characterization of the enzyme in human serum and breast milk.

Lipoamidase activity was detected in human serum with both lipoyllysine (epsilon-N-(DL-lipoyl)-L-Lysine) and lipoylPABA (N-DL-lipoyl-p-aminobenzoate) as substrates, whereas lipoamidase in human milk used lipoylPABA, but not lipoyllysine as substrate. This suggested that lipoamidase activities in serum and milk are due to different enzymes. Studies with activators and inhibitors suggested that lipoamidase in serum using lipoylPABA as substrate may be a different enzyme from that using lipoyllysine as substrate. We suggest that these lipoamidases are named lipoyllysine hydrolase (LLH) and lipoylPABA hydrolase (LPH), respectively. Serum LLH was activated by thiol compounds and EDTA and strongly inhibited by sulfhydryl reagents whereas serum LPH was inhibited by sulfhydryl reagents but not activated by thiol compounds or EDTA. Milk LPH was unaffected by these reagents. We suggest that serum LLH and possibly serum LPH are cysteine proteases. LLH was adsorbed on Concanavalin A-Sepharose, indicating that LLH was a glycoprotein.

A sensitive gas chromatographic method for determination of protein-associated sulfur.

A sensitive method for the determination of elemental sulfur bound to serum albumin and other proteins has been devised. The sample is treated with a hexane solution of triphenylphosphine, and the triphenylphosphine sulfide formed is determined by gas chromatography with a flame photometric sulfur detector. The detection limit of the method is 0.3 microM albumin-associated sulfur. Protein-associated sulfur was not detected in plasma from rats or normal human beings, findings that do not support an earlier suggested transport function of serum albumin for sulfur. Significant amounts of protein-associated sulfur, however, were found in certain rat tissues.

Determination of 3-mercaptolactate, mercaptoacetate and N-acetylcysteine in urine by gas chromatography.

A method is described for the determination of 3-mercaptolactate, mercaptoacetate (thioglycolate) and N-acetylcysteine in urine. As these compounds are mainly excreted as their mixed disulfides with cysteine, they are first reduced to the free thiols by an insoluble polymer containing thiol groups. After purification by chromatography on an organomercurial adsorbent, the compounds are converted to benzyl derivatives by extractive alkylation and determined by gas chromatography. The identity of the compounds analyzed was verified by mass spectrometry. It was demonstrated that mercaptolactate and mercaptoacetate are almost entirely excreted as their mixed disulfides with cysteine, whereas appreciable amounts of N-acetylcyteine are present as the symmetrical disulfide and the free thiol. The urinary excretion of the compounds from healthy human beings was also studied.