Hypertrophy of medial globus pallidus and substantia nigra reticulata in 6‐hydroxydopamine‐lesioned rats treated with L‐DOPA: Implication for L‐DOPA‐induced dyskinesia in Parkinson's disease

The medial globus pallidus plays a crucial role in generation of L‐DOPA‐induced dyskinesia in patients with Parkinson's disease. The 6‐hydroxydopamine‐lesioned rat exhibiting behavioral sensitization to L‐DOPA is one useful animal model for examining L‐DOPA‐induced dyskinesia. To determine neuropathological abnormality responsible for behavioral sensitization, the medial globus pallidus and the substantia nigra reticulata in 6‐hydroxydopamine‐lesioned rats treated with L‐DOPA were examined. Intermittent L‐DOPA treatment induced hypertrophy of the lesioned‐side of medial globus pallidus and substantia nigra reticulata of 6‐hydroxydopamine‐lesioned rats with behavioral sensitization to L‐DOPA. Additionally, coadministration of a 5‐HT_1A receptor agonist, 8‐hydroxy‐2(di‐n‐propylamino)tetralin with L‐DOPA, alleviated the hypertrophy with improvement of the behavioral sensitization. These results suggest that hypertrophy of the medial globus pallidus and substantia nigra reticulata is associated with induction of behavioral sensitization to L‐DOPA in 6‐hydroxydopamine‐lesioned rats. Therefore, neuropathological changes corresponding to hypertrophy might underlie L‐DOPA‐induced dyskinesia in patients with Parkinson's disease.     

Possible involvement of organic anion transporter 2 on the interaction of theophylline with erythromycin in the human liver.

Organic anion transporter 2 (Oat2 [SLC22A7]) is a multispecific organic anion transporter. Although several substrates of human Oat2 (hOat2) have been elucidated, a possible involvement of hOat2 in drug interaction is less defined. The purpose of this study was to investigate the interaction of theophylline with erythromycin mediated by hOat2 using a Xenopus laevis oocyte expression system. When expressed in Xenopus oocytes, hOat2 mediated the transport of theophylline and erythromycin. The finding indicates that the two compounds are novel substrates for hOat2. The apparent K(m) values for the uptake of hOat2 that mediated the transport of theophylline and erythromycin were 12.6 muM and 18.5 muM, respectively. The hOat2-mediated uptake of [(14)C]theophylline and [(14)C]erythromycin was cis-inhibited by adding erythromycin and theophylline, respectively. Our present findings suggest that hOat2 may, at least in part, be involved in the theophylline-erythromycin interaction in the human liver.     

Interrelationship between secretion, protein phosphorylation and intracellular Ca2+ concentration in platelets stimulated by thrombin or thromboxane A2 analogue

The interrelationship between ATP-secretion, protein phosphorylation and intracellular Ca²⁺ concentration ([Ca²⁺]i) was studied in both ³²P and quin 2 loaded human platelets stimulated by thrombin or thromboxane A₂ analogue (STA₂). In platelets stimulated by thrombin, the degree of 47,000 dalton polypeptides (P47) phosphorylation was observed in completely dose-related manner, regardless of the amount of [Ca²⁺]i. In the same condition, the degree of myosin light chain (P20) phosphorylation, however, was well correlated with ATP secretion and [Ca²⁺]i, when platelets were stimulated by lower dose of thrombin. The similar results were obtained in platelets stimulated by STA₂. These findings suggested that P20, but not P47, phosphorylation in activated platelets is mediated by a rise of [Ca²⁺]i and is well correlated with the secretory reaction. It was unlikely that P47 phosphorylation plays any role in promoting platelet activation.     

An immunodominant haptenic epitope of carbamazepine detected in serum from patients given long-term treatment with carbamazepine without allergic reaction

An anticarbamazepine antibody was detected in the serum of a patient with severe carbamazepine-induced serum sickness. We found that the patient's T cells and IgG antibody recognized an epitope which appeared in subjects showing an allergic reaction, as well as that in subjects who showed no allergic reaction, after long-term carbamazepine therapy. These results show that an anti-carbamazepine immune response does not occur in the majority of subjects who undergo long-term carbamazepine therapy without developing allergic symptoms, although the immunodominant haptenic epitope of carbamazepine is present in their sera.     

Neural cell adhesion molecule contributes to hemopoiesis-supporting capacity of stromal cell lines

To clarify mechanisms underlying cell-to-cell interactions between hemopoietic stem cells (HSCs) and stromal cells, we established a stromal cell line (FMS/PA6-P) from day-16 fetal bone marrow (BM) adherent cells using an anti-PA6 monoclonal antibody (mAb) specific for BM stromal cells. Importantly, this FMS/PA6-P cell line, showing homogenous fibroblastic morphology, is absent from hematolymphoid and endothelial lineage markers and maintains a high level of expression of PA6 molecule, recognized by the anti-PA6 mAb, for approximately 20 passages. Further, the cell line expressing a high level of PA6 molecule has a better hemopoiesis-supporting capacity in vitro than other stromal cell lines such as PA6 and MS-5. In fact, the PA6 molecule is closely related to the hemopoiesis-supporting capacity of the stromal cells because the proliferation of HSCs was suppressed to a great extent by the anti-PA6 mAb. Affinity chromatography and mass peptide fingerprinting revealed that the protein reacting with the anti-PA6 mAb is neural cell adhesion molecule (NCAM). The frequencies of long-term cobblestone area-forming cells and long-term culture-initiating cells were significantly suppressed by repression of NCAM in the FMS/PA6-P cells using NCAM small interfering RNA. Our findings clearly indicate that NCAM functions on the maintenance of HSCs.     

Atomic force microscopy to study direct neurite-mast cell (RBL) communication in vitro

Communication between nerves and mast cells is a prototypic demonstration of neuroimmune interaction. We used an in vitro co-culture approach comprising cultured murine superior cervical ganglia (SCG) and rat basophilic leukemia (RBL-2H3) cells. Atomic force microscopy (AFM) showed how neurites attached to a pseudopodium or a cell body of an RBL cell. After stimulation of SCG neurites with bradykinin or scorpion venom, RBL cells attached to neurites spread and flattened, and several discharged granules (0. 5-1.0 microm in diameter) were found on the surface of the RBL cells. A neurokinin (NK)-1 receptor (i.e. substance P receptor) antagonist prevented the RBL degranulation. The results showed that activation of the SCG neurites with bradykinin or scorpion venom was able to elicit degranulation in RBL cells which were attached to neurites.     

Intra-bone marrow-bone marrow transplantation facilitates hemopoietic recovery including dendritic cells

In this report, we provide evidence using a serial bone marrow transplantation (BMT) protocol that intra-bone marrow (IBM)-BMT (IBM-BMT) can efficiently reconstitute the hemopoietic system with cells of donor origin, in contrast to conventional intravenous (IV)-BMT (IV-BMT). Furthermore, the hematolymphoid system of secondary recipients that had received bone marrow cells (BMCs) from primary recipients treated with IBM-BMT recovered earlier than that of the secondary recipients of BMCs from primary recipients treated with IV-BMT. This was the case when the Lin-/c-kit+ progenitor cells of the secondary and tertiary recipients were examined. These findings indicate that IBM-BMT can facilitate the development of not only cells of various lineages but also the effective generation and, more importantly, the maintenance of the progenitor cells. Furthermore, we show that IBM-BMT can reconstitute the dendritic cell (DC) subsets (myeloid and lymphoid DCs), which are critical for the initiation of both adaptive and innate immune responses. The frequency of both myeloid and lymphoid DC subsets was approximately equal to that of normal age-matched untreated controls and, after second and third BMT, this ratio was close to that observed in the normal controls. However, the lymphoid DCs were clearly reduced in the secondary and tertiary recipients of BMCs from mice that had received IV-BMT. Therefore, the development of DC subsets is also normally maintained in the IBM-BMT group.     

Manganese deposition in the globus pallidus in patients with biliary atresia

BACKGROUND: Chronic liver diseases may alter trace element contents in the brain. Among these trace elements, manganese is a ubiquitous transition metal excreted by the liver into the bile. Blood concentrations of manganese are elevated in patients with biliary atresia who have undergone hepatic portoenterostomy. The present study investigated the effects of liver transplantation on manganese deposition in the brain in such patients. METHODS: The signal intensity of the globus pallidus was calculated as an index defined as the percentile ratio of signal intensity in the globus pallidus to the subcortical frontal white-matter in sagittal T1-weighted magnetic resonance imaging planes. RESULTS: Brain magnetic resonance imaging revealed hyperintense signals in the globus pallidus due to manganese deposition in biliary atresia patients. Few neurologic symptoms related to manganese intoxication were observed. However, one 23-year-old female with biliary atresia had depressive symptoms and dyskinesia; she improved after oral administration of the dopamine precursor, L-DOPA. Manganese deposition disappeared in two patients after living-related reduced-size hepatic transplantation. CONCLUSIONS: Manganese accumulates in the brain during cholestasis associated with biliary atresia and disappears after hepatic transplantation. Manganese deposition is likely to be subclinical and reversible but may be associated with some age-related neurologic symptoms.     

Manganese deposits in patients with biliary atresia after hepatic porto-enterostomy

PURPOSE: The aim of this study was to determine if there is latent manganese toxicity in patients with biliary atresia. METHODS: Fifteen children with biliary atresia were examined postoperatively with regard to whole-blood manganese levels using brain magnetic resonance imaging (MRI) and I-123 iodoamphetamine (IMP) per rectal portal scintigraphy. RESULTS: Nine (60%) of the 15 had high whole-blood manganese levels (mean, 4.1 microg/dL; range, 1.2 to 9.6; normal, 0.5 to 2.5), and these 9 had hyperintense globus pallidus on T1-weighted images, with no corresponding signal change in T2 sequences. I-123 IMP per rectal portal scintigraphy was done for 13 patients to evaluate portosystemic shunt flow. 12 (92%) of these patients had an increased flow. Mean shunt ratio was estimated to be 41% (range, 0.6 to 98; normal, <5%). Encephalopathy was evident in only 1 patient. CONCLUSIONS: Some patients with biliary atresia in the postoperative period have manganese deposits in globus pallidus on T1-weighted images and high whole-blood manganese levels, possibly caused by increased portsystemic shunt, and a latent or subclinical encephalopathy is also present.