Analysis of nerve fibers and their distribution in histologic sections of the human brain

The field of quantitative analysis and subsequent mapping of the cerebral cortex has developed rapidly. New powerful tools have been applied to investigate large regions of complex folded gyrencephalic cortices in order to detect structural transition regions that might partition different cortical fields of disjunct neuronal functions. We have developed a new mapping approach based on axoarchitectonics, a method of cortical visualization that previously has been used only indirectly with regard to myeloarchitectonics. Myeloarchitectonic visualization has the disadvantage of producing strong agglomerative effects of closely neighbored nerve fibers. Therefore, single and neurofunctional-relevant parameters such as axonal branchings, axon areas, and axon numbers have not been determinable with satisfying precision. As a result, different staining techniques had to be explored in order to achieve a suitable histologic staining for axon visualization. The best results were obtained after modifying the Naoumenko-Feigin staining for axons. From these contrast-rich stained histologic sections, videomicroscopic digital image tiles were generated and analyzed using a new fiber analysis framework. Finally, the analysis of histologic images provided topologic ordered parameters of axons that were transferred into parameter maps. The axon parameter maps were analyzed further via a recently developed traverse generating algorithm that calculated test lines oriented perpendicular to the cortical surface and white matter border. The gray value coded parameters of the parameter maps were then transferred into profile arrays. These profile arrays were statistically analyzed by a reliable excess mass approach we recently developed. We found that specific axonal parameters are preferentially distributed throughout granular and agranular types of cortex. Furthermore, our new procedure detected transition regions originally defined by changes of cytoarchitectonic layering. Statistically significant inhomogeneities of the distribution of certain axon quantities were shown to indicate a subparcellation of areas 4 and 6. The quantification techniques established here for the analysis of spatial axon distributions within larger regions of the cerebral cortex are suitable to detect inhomogeneities of laminar axon patterns. Hence, these techniques can be recommended for systematic and observer-supported cortical area mapping and parcellation studies.

Family history and risk of atopic dermatitis in children up to 4 years

BACKGROUND

The aetiology of atopic dermatitis (AD) is presumably multi-factorial, with interactions between genetic and environmental factors.

OBJECTIVE

To investigate the relation between atopic family history and development of AD up to 4 years.

METHODS

Using annual questionnaires, we studied the cumulative incidence of AD in 0-4-year-olds in a prospective birth cohort of 4089. Atopic diseases in parents and siblings were recorded at birth. The occurrence of serum immunoglobulin E (IgE) antibodies to inhalant and food allergens was analysed in 2614 4-year-olds, and AD was divided into non-IgE-associated and IgE-associated.

RESULTS

Of the children without atopic parents, 27.1% developed AD; of those with single or double parental atopic history, 37.9% and 50.0%, respectively, did so. The effects of parental history of eczema and of atopic respiratory disease (ARD) did not differ significantly, nor did those of maternal and paternal history. Parental history of ARD increased the risk significantly more for IgE-associated AD than for non-IgE-associated AD (odds ratio (OR) 2.0; 95% confidence interval (CI) 1.5-2.8 vs. OR 1.3; 95% CI 1.0-1.8), whereas the two forms lacked major differences in the effect of parental eczema. A history of eczema in older siblings was a risk indicator for both forms of AD (OR 2.1; 95% CI 1.4-3.3 vs. OR 1.8; 95% CI 1.2-2.6).

CONCLUSIONS

We found no difference between the effects of maternal and paternal atopic history. Parental eczema was a risk factor for AD irrespective of its association with IgE, but parental history of ARD mainly increased the risk of IgE-associated AD.

A robust transcortical profile scanner for generating 2-d traverses in histological sections of richly curved cortical courses

Quantitative analysis of the cerebral cortex has become more important since neuroimaging methods have revealed many subfunctions of cortical regions that were thought to be typical for only one specific function. Furthermore, it is often unknown if a certain area may be subdivided observer independently into subareas. These questions lead to an analytical problem. How can we analyze the cytoarchitecture of the human cerebral cortex in a quantitative manner in order to confirm classical transition regions between distinct areas and to detect new ones. Scanning the cerebral cortex is difficult because it presents a richly curved course and sectioning always leads to partially nonperpendicular sectioned regions of the tissue. Therefore, different methods were tested to determine which of them are most reliable with respect to generating perpendicular testlines in the cerebral cortex. We introduce a new technique based on electrical field theory. The results of this technique are compared with those of conventional techniques. It was found that straight traverses generated by the electrodynamic model present significantly smaller intertraversal differences than the conventional approaches.

Clinical features of atopic dermatitis at two years of age: a prospective, population-based case-control study

While atopic dermatitis (AD) usually presents early in life, few prospective studies focus on young children with AD. The objective of this study was to characterize, phenotypically and prospectively, young children with AD. From a community birth cohort of 2,256 children, consecutive children with AD (n = 221) were followed to 2 years of age, when they were re-examined and screened for atopic sensitization (skin-prick test to foods; Phadiatop). Ninety-nine controls were also examined. AD debuted during the first year in 88% of cases. At the 2-year examination, when the children had already undergone topical treatment, 157/221 (71%) had ongoing eczema ranging among mild (45%), moderate (53%) and severe (2%). Airway problems indicating asthma had occurred in 9% of cases and 6% of controls (not significant), and allergic rhinoconjunctivitis in 5% and 0%, respectively (p<0.05). The skin-prick test to common food allergens was positive in 27% of cases and Phadiatop was positive in 15%. In 67% both tests were negative. Eczema severity did not differ between sensitized and non-sensitized children. Positive Phadiatop was more common in boys than in girls with ongoing AD (22% vs 3%, p<0.01), and more boys than girls had ongoing AD (82% vs 59%, p<0.001); otherwise, no differences attributable to gender were found.

Hanifin's and Rajka's minor criteria for atopic dermatitis: which do 2-year-olds exhibit?

BACKGROUND

In 1980 Hanifin and Rajka published major and minor criteria for atopic dermatitis (AD). Despite the early age at onset of AD, there are few prospective studies in young children of the prevalence of signs and symptoms meeting the minor criteria.

OBJECTIVE

Our purpose was to identify those of Hanifin's and Rajka's minor criteria that are most frequent in 2-year-old children with AD and in controls.

METHODS

Consecutive patients with AD (n = 221), 24 months of age or younger, were followed up to 2 years, when they were re-examined. The minor criteria were divided into 33 subcriteria, 29 of which were examined. Controls (n = 99), matched for age and sex, with no history of eczema at 2 years of age were examined in the same way.

RESULTS

At the 2-year examination 157 of 221 had ongoing AD. Seven minor criteria were met in more than one fourth of these children, namely xerosis (100%), course influenced by environmental factors (87%), facial erythema (54%), skin reactions provoked by ingested food (39%), itch when sweating (34%), positive skin prick test (29%), and hand eczema (28%). In the control group, only xerosis (40%), facial erythema (25%), and skin reactions provoked by ingested food (9%) were present in 4% or more.

CONCLUSION

Approximately half of the 29 criteria investigated were met in 3% or fewer of the cases, indicating that they may not be of much help to the clinician. Of the minor criteria of Hanifin and Rajka, only xerosis, course influenced by environmental factors, and facial erythema were seen in a majority of patients and would therefore be useful in the diagnosis of AD.

Solid- and liquid-phase extraction for the gas chromatographic-tandem mass spectrometric quantification of 2,3-dinor-thromboxane B2 and 2,3-dinor-6-oxo-prostaglandin F1 alpha in human urine

Whole body synthesis of thromboxane A2 is best assessed by quantifying non-invasively its major urinary metabolite, i.e., 2,3-dinor-thromboxane B2 (2,3-dn-TxB2), by gas chromatography-mass spectrometry (GC-MS) or GC-tandem MS. Methods based on these techniques usually require a series of extraction and purification procedures including solid-phase extraction (SPE) and thin-layer chromatography (TLC) or liquid chromatographic separation of authentic or derivatized 2,3-dn-TxB2. Taking advantage of the inherent accuracy of GC-tandem MS and the high selectivity of the extraction of methoximated 2,3-dn-TxB2 on phenylboronic acid SPE cartridges we developed a method that involves only SPE steps prior to quantification by GC-tandem MS. The method was validated by performing in parallel an additional TLC step. Method mean accuracy and precision were of the order of 103% and 95%, respectively. The method allows furthermore co-processing of the same urine sample to quantify accurately and rapidly the major urinary metabolite of prostacyclin, i.e., 2,3-dn-6-oxo-prostaglandin (PG) F1 alpha, by GC-tandem MS. The limit of detection of the method was below each 5 pg of 2,3-dn-TxB2 and 2,3-dn-6-oxo-PGF1 alpha per 5 ml of urine. Our study suggests that dinor metabolites of isothromboxanes and isoprostacyclins are not abundantly present in human urine.

Incidence of Lyme borreliosis in the Würzburg region of Germany

To assess the incidence of Lyme borreliosis in Central Europe, a 12-month, prospective, population-based surveillance study of Lyme borreliosis was conducted in the Wurzburg region of central Germany, following an aggressive awareness campaign. The diagnosis of Lyme borreliosis required the presence of (i) erythema migrans (diameter > or =5 cm); (ii) lymphocytoma; or (iii) another specific manifestation including Lyme arthritis, neuroborreliosis, carditis or acrodermatitis chronica atrophicans in conjunction with serological confirmation. A total of 313 cases of Lyme borreliosis was diagnosed, giving an incidence of 111 cases/100000 inhabitants, the highest rates occurring in children and elderly adults living in wooded as opposed to agricultural areas. The incidence in city dwellers and inhabitants of rural areas was not significantly different. Erythema migrans was the only manifestation in 279 (89%) patients. Of the 34 patients with manifestations other than erythema migrans alone, 15 had arthritis, nine neuroborreliosis, six lymphocytoma, four acrodermatitis chronica atrophicans and one carditis. Children were more likely than adults to have manifestations other than erythema migrans alone. Lyme borreliosis was very common in central Germany, and one of the most frequent bacterial infections. The observation of more cases of arthritis than neuroborreliosis was similar to that in the USA. These results may be representative for many parts of central Europe and suggest the need for development of a vaccine against borreliosis caused by European strains of Borrelia species.

Selective inhibition of MDR1 P-glycoprotein-mediated transport by the acridone carboxamide derivative GG918

The acridone carboxamide derivative GG918 (N-{4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)-ethyl]-pheny l}-9,10dihydro-5-methoxy-9-oxo-4-acridine carboxamide) is a potent inhibitor of MDR1 P-glycoprotein-mediated multidrug resistance. Direct measurements of ATP-dependent MDR1 P-glycoprotein-mediated transport in plasma membrane vesicles from human and rat hepatocyte canalicular membranes indicated 50% inhibition at GG918 concentrations between 8 nM and 80 nM using N-pentyl-[3H]quinidinium, ['4C]doxorubicin and [3H]daunorubicin as substrates. The inhibition constant K for GG918 was 35 nM in rat hepatocyte canalicular membrane vesicles with [3H]daunorubicin as the substrate. Photoaffinity labelling of canalicular and recombinant rat Mdr1b P-glycoprotein by [3H]azidopine was suppressed by 10 muM and 40 muM GG918. The high selectivity of GG918-induced inhibition was demonstrated in canalicular membrane vesicles and by analysis of the hepatobiliary elimination in rats using [3H]daunorubicin, [3H]taurocholate and [3H]cysteinyl leukotrienes as substrates for three distinct ATP-dependent export pumps. Almost complete inhibition of [3H]daunorubicin transport was observed at GG918 concentrations that did not affect the other hepatocyte canalicular export pumps. The high potency and selectivity of GG918 for the inhibition of human MDR1 and rat Mdr1b P-glycoprotein may serve to interfere with this type of multidrug resistance and provides a tool for studies on the function of these ATP-dependent transport proteins.

[Despite better knowledge of pathogenesis and treatment: atopic eczema--a disease with increasing incidence in Sweden]

The past twenty years have witnessed an increasing incidence of atopic dermatitis in Western Europe. The article consists in a discussion of the pathogenesis, clinical signs and treatment of this common skin disease. Both an IgE-mediated reaction on epidermal Langerhans cells, and a physiological/biochemical defect of the skin barrier structure may be crucial factors of the multifactorial pathogenesis. Local treatment with corticosteroids and moisturisers remains the basic approach, though the development of new more specific treatments is under way. Although much remains to be learned about atopic dermatitis, today all patients can be offered effective treatment resulting in improved quality of life.

Dietary L-arginine and alpha-tocopherol reduce vascular oxidative stress and preserve endothelial function in hypercholesterolemic rabbits via different mechanisms

Vascular oxidative stress brought about by superoxide radicals and oxidized low-density lipoproteins (oxLDL) is a major factor contributing to decreased NO-dependent vasodilator function in hypercholesterolemia and atherosclerosis. We investigated whether chronic administration of L-arginine (2% in drinking water) or of alpha-tocopherol (300 mg/day) improves endothelium-dependent vasodilator function and systemic NO production, reduces vascular oxidative stress, and reduces the progression of atherosclerosis in cholesterol-fed rabbits with pre-existing hypercholesterolemia. Systemic NO production was assessed as urinary nitrate excretion; oxidative stress was measured by urinary 8-iso-PGF2alpha excretion in vivo, by lucigenin-enhanced chemiluminescence of isolated aortic rings ex vivo, and by copper-mediated LDL oxidation in vitro. Endothelium-dependent relaxation was almost completely abrogated in cholesterol-fed rabbits. Urinary nitrate excretion was reduced by 46+/-10%, and 8-iso-PGF2alpha excretion was increased by 61+/-18% as compared to controls (each P <0.05). Vascular superoxide radical release stimulated by PMA ex vivo was increased by 273+/-93% in this group, and the lag time of LDL oxidation was reduced by 35+/-6% (each P <0.05). Treatment with L-arginine and alpha-tocopherol reduced intimal lesion formation (by 68+/-6 and 4+/-11%, respectively; P <0.05) and improved endothelium-dependent relaxation. Both treatments also normalized urinary 8-iso-PGF2alpha excretion. L-Arginine increased urinary nitrate excretion by 43+/-13% (P <0.05) and reduced superoxide radical release by isolated aortic rings to control levels, which was unaffected by vitamin E treatment. By contrast, vitamin E dramatically increased the resistance of isolated LDL to copper-mediated oxidation in vitro by 178+/-7% (P <0.05), which was only marginally prolonged by L-arginine. Intimal thickening was reduced by both treatments. We conclude that both L-arginine and alpha-tocopherol reduce the progression of atherosclerotic plaques in cholesterol-fed rabbits. However, while L-arginine increases NO formation and reduces superoxide release, alpha-tocopherol antagonizes mainly oxLDL-related events in atherogenesis. Thus, both treatments reduce urinary isoprostane excretion and improve endothelium-dependent vasodilation via different mechanisms.

Dietary L-arginine normalizes endothelin-induced vascular contractions in cholesterol-fed rabbits

The endothelium regulates vascular function by releasing the vasodilator autacoid nitric oxide (NO) and the vasoconstrictor peptide endothelin-1 (ET-1). Impaired activity of NO as well as excessive activity of ET-1 have been demonstrated in hypercholesterolemia and atherosclerosis. Because dietary L-arginine can restore NO function and improve abnormal endothelium-dependent relaxation in hypercholesterolemic rabbits, we examined the effects of dietary supplementation with L-arginine in cholesterol-fed rabbits on endothelium-dependent vascular relaxation and ET-1-induced vascular contraction, as well as the systemic synthesis of ET-1. Rabbits were initially fed a diet enriched with 1% cholesterol for 4 weeks, followed by 0.5% cholesterol alone or supplemented with 2% L-arginine in drinking water during the next 12 weeks. Cholesterol feeding impaired endothelium-dependent relaxation of rabbit aortic rings ex vivo and increased urinary immunoreactive ET-1 excretion, along with decreased urinary nitrate excretion, an index of NO production. L-Arginine partially restored endothelium-dependent relaxation in parallel to increased urinary nitrate excretion and decreased urinary immunoreactive ET-1 excretion. Selective inhibition of ET-A receptors with BQ123 partially restored endothelium-dependent relaxation in hypercholesterolemic rabbits but had no effect on arterial rings from rabbits supplemented with L-arginine or from control animals. The contractile vascular response of aortic rings to exogenous ET-1 was increased in rabbits fed a high-cholesterol diet; this enhanced contractility to ET-1 was completely reversed by L-arginine. These data suggest that L-arginine restores endothelial function and normalizes the synthesis and vasoconstrictor response to ET-1 in hypercholesterolemia.

Chronic dietary supplementation with L-arginine inhibits platelet aggregation and thromboxane A2 synthesis in hypercholesterolaemic rabbits in vivo

OBJECTIVES

L-arginine exerts anti-atherosclerotic effects in hypercholesterolaemic rabbits via modulating endogenous NO production. We investigated whether L-arginine inhibits thromboxane formation in vivo and platelet aggregation ex vivo in this animal model.

METHODS

The urinary excretion rates of 2,3-dinor-6-keto-PGF1 alpha (major urinary metabolite of PGI2) and 2,3-dinor-TXB2 (major urinary metabolite of thromboxane A2) were used as indicators of platelet-endothelial cell interactions in vivo. Rabbits were fed 1% cholesterol (Cholesterol group, N = 8), 1% cholesterol plus 2.25% L-arginine (Cholesterol + L-arginine, N = 8), or normal rabbit chow (Control, N = 4) for 12 weeks. Urine samples were collected in weekly intervals. At the end of the study period platelet aggregation ex vivo and endothelium-dependent and -independent vascular function of isolated aortic rings in vitro was assessed.

RESULTS

Urinary 2,3-dinor-TXB2 excretion significantly increased in the cholesterol group (p < 0.05), and endogenous NO formation (measured as urinary nitrate excretion) decreased (p < 0.05). Both parameters were significantly correlated with each other (R = 0.48, p < 0.01). L-arginine partly restored urinary nitrate excretion and significantly reduced TXA2 production to values even below those in the control group (p < 0.001). Urinary 2,3-dinor-6-keto-PGF1 alpha excretion increased in early hypercholesterolaemia and returned to control values in the second half of the study period. The early increase in urinary 2,3-dinor-6-keto-PGF1 alpha excretion was attenuated by L-arginine. Platelet aggregation was significantly enhanced in cholesterol-fed rabbits and attenuated by dietary L-arginine. L-arginine also improved the impaired endothelium-dependent relaxations to ADP, and normalized the vasoconstrictor effects of 5-HT in isolated aortic rings.

CONCLUSIONS

Cholesterol-feeding enhances platelet aggregation and TXA2 formation, and stimulates platelet-endothelial cell interaction in rabbits. These effects are probably due to impaired NO elaboration, as indicated by decreased urinary nitrate excretion. Chronic dietary supplementation with L-arginine elevates systemic NO elaboration and significantly increases the PGI2/TXA2 ratio. It thus beneficially influences the homeostasis between vasodilator and vasoconstrictor prostanoids in vivo.

Dietary L-arginine reduces the progression of atherosclerosis in cholesterol-fed rabbits: comparison with lovastatin

BACKGROUND

We investigated whether L-arginine induces regression of preexisting atheromatous lesions and reversal of endothelial dysfunction in hypercholesterolemic rabbits, whether similar effects can be obtained by cholesterol-lowering therapy with lovastatin, and which mechanism leads to these effects.

METHODS AND RESULTS

Rabbits were fed 1% cholesterol for 4 weeks and 0.5% cholesterol for an additional 12 weeks. Two groups of cholesterol-fed rabbits were treated with L-arginine (2.0% in drinking water) or lovastatin (10 mg/d) during weeks 5 through 16. Systemic nitric oxide (NO) formation was assessed as the urinary excretion rates of nitrate and cGMP in weekly intervals. Cholesterol feeding progressively reduced urinary nitrate excretion to approximately 40% of baseline (P<.05) and increased plasma concentrations of asymmetrical dimethylarginine (ADMA), an endogenous NO synthesis inhibitor. Dietary L-arginine reversed the reduction in plasma L-arginine/ADMA ratio and partly restored urinary excretion of nitrate and cGMP (each P<.05 vs cholesterol) but did not change plasma cholesterol levels. L-Arginine completely blocked the progression of carotid intimal plaques, reduced aortic intimal thickening, and preserved endothelium-dependent vasodilator function. Lovastatin treatment reduced plasma cholesterol by 32% but did not improve urinary nitrate or cGMP excretion or endothelium-dependent vasodilation. Lovastatin had a weaker inhibitory effect on carotid plaque formation and aortic intimal thickening than L-arginine. L-Arginine inhibited but lovastatin potentiated superoxide radical generation in the atherosclerotic vascular wall.

CONCLUSIONS

Dietary L-arginine improves NO-dependent vasodilator function in cholesterol-fed rabbits and completely blocks the progression of plaques via restoration of NO synthase substrate availability and reduction of vascular oxidative stress. Lovastatin treatment has a weaker inhibitory effect on the progression of atherosclerosis and no effect on vascular NO elaboration, which may be due to its stimulatory effect on vascular superoxide radical generation.

Lipoid proteinosis in three children

We report on three children with lipoid proteinosis, an autosomal recessive disorder characterized by the deposition of hyaline-like material in the skin, mucous membranes and other tissues. All cases had characteristic hoarseness. Other symptoms observed were infiltrated whitish plaques and pock-like scars on the face, papules on the palpebral margins, and infiltrates in the mucous membranes of the lower lip and tongue. Two of the children were siblings whose parents were first cousins.

Establishment and characterization of permanent human endothelial cell clones

Though vasculitic diseases have been claimed to be associated with anti-endothelial cells antibodies (AECA), there is a widespread awareness of the limitations of the tests currently in use. Our objective was therefore to establish clones, in the hope that some of them would express disease-specific membrane autoantigens. Two EC lines and 7 clones were established by fusing human umbilical vein EC with epithelial A549/8 cells, and cloning by limiting dilution. An additional clone was derived from the EA.hy 926 cell line. All clones carried EC markers, such as thrombomoduline (TM) and platelet-EC adhesion molecule 1 but differed from each other, depending on whether they expressed HLA class II antigen, LFA-1, thrombospondin receptor or von Willebrand factor (vWf) antigen. Clones were also characterized by their ability to release tissue plasminogen activator, interleukin 6, TM and vWf. This panel is meant to distinguish reactivities of AECA.

-Cytokine level in malignant ascites and peripheral blood of patients with advanced ovarian carcinoma-

The concentrations of various cytokines were examined by ELISA in blood and in ascites from 14 patients with advanced ovarian cancer (stage IV). The control group consisted of 6 patients with benign gynaecological disorders. Compared with patients with benign gynaecological disorders, ascites and/or plasma of patients with ovarian cancer showed significantly higher levels of IL-6, IL-8, IL-10, TNF-alpha, and sIL-2R. There were no increases of IL-1 alpha, IL-1 beta, IL-2, IFN-gamma, and sCD14 levels. The possible pathogenetic significance of cytokines in ovarian cancer is discussed.

[Leukocyte and lymphocyte populations in peripheral blood and malignant ascites in patients with ovarian carcinoma]

Ascites and peripheral blood of 12 patients with advanced ovarian cancer (stage IV) have been investigated by two-color flow cytometry for leukocytes and lymphocyte subsets with monoclonal antibodies, against CD3, CD4, CD8, CD14, CD16/56, CD19, CD25, CD45, CD57, and HLA-DR. Ascites compared with blood showed a significant raise of CD3-positive lymphocytes (80 +/- 14% vs. 69 +/- 8%) and a significant reduction of CD57-positive lymphocytes (13.6 +/- 13% vs 24 +/- 21%). There was an increased expression of HLA-DR on CD3-positive lymphocytes in malignant ascites. The results are discussed with regard to a supposedly defective local immune defense against the tumor.

[Effect of granulocyte colony stimulating factor (G-CSF) on peripheral blood leukocytes and lymphocytes in patients with chemotherapy-induced leukopenia]

In patients with extensive chemotherapy, G-CSF abrogated leukopenia following administration of cytotoxic agents. Six women with ovarian cancer and chemotherapy-induced leukopenia received 300 micrograms Filgrastrim (r-metHuG-CSF, Neupogen 30; AMGEN, Germany) daily for 10 days. Leukocytes and lymphocyte subsets of peripheral blood were determined before, throughout and after subcutaneous injections of G-CSF by flow cytometry using monoclonal antibodies to CD3, CD4, CD8, CD14, CD16/56, CD19 and CD45. It could be observed that not only neutrophils (23 fold) but also lymphocytes (6 fold) and monocytes (10 fold) showed a dramatic increase in cell counts throughout and after G-CSF administration. This is in contrast to previous reports, where only effects on neutrophils were described. In spite of the increase in lymphocytes the relative percentage of CD3+, CD19+, CD3-CD16/CD56+, CD3+, CD8+ and CD3+ CD4+ lymphocyte subsets did not change throughout and after therapy, except for an increased expression of HLA-DR on CD3+ lymphocytes.

Hepatobiliary elimination of the peroxisome proliferator nafenopin by conjugation and subsequent ATP-dependent transport across the canalicular membrane

Amphiphilic carboxylates acting as peroxisome proliferators and hypolipidemic drugs induce enzymes of peroxisomal lipid beta-oxidation, certain drug-metabolizing enzymes in the liver, and a number of additional proteins. The peroxisome proliferators represent a well-established class of non-genotoxic hepatocarcinogens. In this study we characterized the hepatic elimination of the peroxisome proliferator nafenopin. In the rat in vivo, 1 hr after intravenous administration of [3H]nafenopin, approx. 40% of injected radioactivity was recovered in bile. HPLC analysis of bile samples revealed that only about 10% of the radioactivity recovered in bile was associated with non-metabolized nafenopin and approx. 90% with more polar metabolites. One of the main metabolites formed in the liver and excreted into bile was identified as nafenopin glucuronide by beta-glucuronidase-catalysed reconversion to nafenopin. In mutant rats deficient in the canalicular transport of leukotriene C4 and related amphiphilic anion conjugates, recovery of [3H]nafenopin-derived radioactivity in bile was reduced to 4% of the injected dose. Although nafenopin glucuronide could not be detected in bile, it was a major metabolite in the liver from these mutant rats. Using membrane vesicles enriched in bile canalicular membranes from normal rats, transport of nafenopin glucuronide was shown to be a primary-active ATP-dependent process which was inhibited by leukotriene C4 and S-dinitrophenyl glutathione with IC50 values of 0.2 and 12 microM, respectively. ATP-dependent transport was not detectable for non-conjugated nafenopin. In canalicular membrane vesicles prepared from the mutant rats, the rate of ATP-dependent transport of nafenopin glucuronide was less than 10% of the transport observed in vesicles from normal rats. These data indicate that conjugation and subsequent transport by the ATP-dependent export carrier for leukotriene C4 and related conjugates is a major pathway for the elimination of nafenopin and structurally-related peroxisome proliferators.

Functional reconstitution of ATP-dependent transporters from the solubilized hepatocyte canalicular membrane

The hepatocyte canalicular membrane contains several primary-active ATP-dependent export carriers including one for bile salts and one for leukotriene C4 and related conjugates. The molecular identity of both transporters has not been fully elucidated. To establish a transport assay that allows the purification and identification of the proteins involved in ATP-dependent bile salt transport and in leukotriene C4 transport, we reconstituted solubilized hepatocyte canalicular membranes into phospholipid bilayers using a rapid dilution method. The proteoliposomes formed exhibited both [3H]taurocholate and [3H]leukotriene C4 uptake, which was much higher in the presence of ATP than in the presence of the non-hydrolyzable ATP-analog AdoPP[CH2]P or in the absence of nucleotides. Nucleotide requirement and osmotic sensitivity of [3H]taurocholate transport indicates true transport into the vesicle lumen. Optimized conditions for reconstitution included the addition of a high concentration of an osmolyte (glycerol) and the presence of exogenous phospholipids (0.3%) during solubilization. Highest transport rates were obtained by reconstitution into acetone/ether-precipitated Escherichia coli phospholipid supplemented with 20% cholesterol and by use of octylglucoside concentrations between 30 mM and 50 mM. Taurocholate transport was non-competitively inhibited by vanadate (Ki = 39 microM). The kinetic parameters of cyclosporin A inhibition (Ki = 2.6 microM for taurocholate and 4.3 microM for leukotriene C4 transport) as well as the affinities of taurocholate (Km = 12 microM) and leukotriene C4 (Km = 0.5 microM) in the proteoliposome system indicate that the reconstitution resulted in functionally active transport systems, which are representative of ATP-dependent transport in the intact plasma membrane.