Long-Read Sequencing Resolves a Complex Structural Variant in PRKN Parkinson's Disease

BACKGROUND

Parkin RBR E3 ubiquitin-protein ligase (PRKN) mutations are the most common cause of young onset and autosomal recessive Parkinson's disease (PD). PRKN is located in FRA6E, which is one of the common fragile sites in the human genome, making this region prone to structural variants. However, complex structural variants such as inversions of PRKN are seldom reported, suggesting that there are potentially unrevealed complex pathogenic PRKN structural variants.

OBJECTIVES

To identify complex structural variants in PRKN using long-read sequencing.

METHODS

We investigated the genetic cause of monozygotic twins presenting with a young onset dystonia-parkinsonism using targeted sequencing, whole exome sequencing, multiple ligation probe amplification, and long-read sequencing. We assessed the presence and frequency of complex inversions overlapping PRKN using whole-genome sequencing data of Accelerating Medicines Partnership Parkinson's disease (AMP-PD) and United Kingdom (UK)-Biobank datasets.

RESULTS

Multiple ligation probe amplification identified a heterozygous exon three deletion in PRKN and long-read sequencing identified a large novel inversion spanning over 7 Mb, including a large part of the coding DNA sequence of PRKN. We could diagnose the affected subjects as compound heterozygous carriers of PRKN. We analyzed whole genome sequencing data of 43,538 participants of the UK-Biobank and 4941 participants of the AMP-PD datasets. Nine inversions in the UK-Biobank and two in AMP PD were identified and were considered potentially damaging and likely to affect PRKN expression.

CONCLUSIONS

This is the first report describing a large 7 Mb inversion involving breakpoints outside of PRKN. This study highlights the importance of using long-read sequencing for structural variant analysis in unresolved young-onset PD cases. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Long-read sequencing resolves a complex structural variant in PRKN Parkinson's disease

Background

PRKN mutations are the most common cause of young onset and autosomal recessive Parkinson's disease (PD). PRKN is located in FRA6E which is one of the common fragile sites in the human genome, making this region prone to structural variants. However, complex structural variants such as inversions of PRKN are seldom reported, suggesting that there are potentially unrevealed complex pathogenic PRKN structural variants.

Objectives

To identify complex structural variants in PRKN using long-read sequencing.

Methods

We investigated the genetic cause of monozygotic twins presenting with a young onset dystonia-parkinsonism using targeted sequencing, whole exome sequencing, multiple ligation probe amplification, and long-read. We assessed the presence and frequency of complex inversions overlapping PRKN using whole-genome sequencing data of AMP-PD and UK-Biobank datasets.

Results

Multiple ligation probe amplification identified a heterozygous exon 3 deletion in PRKN and long-read sequencing identified a large novel inversion spanning over 7Mb, including a large part of the coding DNA sequence of PRKN. We could diagnose the affected subjects as compound heterozygous carriers of PRKN. We analyzed whole genome sequencing data of 43,538 participants of the UK-Biobank and 4,941 participants of the AMP-PD datasets. Nine inversions in the UK-Biobank and two in AMP PD were identified and were considered potentially damaging and likely to affect PRKN isoforms.

Conclusions

This is the first report describing a large 7Mb inversion involving breakpoints outside of PRKN. This study highlights the importance of using long-read whole genome sequencing for structural variant analysis in unresolved young-onset PD cases.

A defined method for differentiating human iPSCs into midbrain dopaminergic progenitors that safely restore motor deficits in Parkinson's disease

Background

Parkinson's disease (PD) is a progressive neurodegenerative condition that primarily affects motor functions; it is caused by the loss of midbrain dopaminergic (mDA) neurons. The therapeutic effects of transplanting human-induced pluripotent stem cell (iPSC)-derived mDA neural progenitor cells in animal PD models are known and are being evaluated in an ongoing clinical trial. However, However, improvements in the safety and efficiency of differentiation-inducing methods are crucial for providing a larger scale of cell therapy studies. This study aimed to investigate the usefulness of dopaminergic progenitor cells derived from human iPSCs by our previously reported method, which promotes differentiation and neuronal maturation by treating iPSCs with three inhibitors at the start of induction.

Methods

Healthy subject-derived iPS cells were induced into mDA progenitor cells by the CTraS-mediated method we previously reported, and their proprieties and dopaminergic differentiation efficiency were examined in vitro. Then, the induced mDA progenitors were transplanted into 6-hydroxydopamine-lesioned PD model mice, and their efficacy in improving motor function, cell viability, and differentiation ability in vivo was evaluated for 16 weeks.

Results

Approximately ≥80% of cells induced by this method without sorting expressed mDA progenitor markers and differentiated primarily into A9 dopaminergic neurons in vitro. After transplantation in 6-hydroxydopamine-lesioned PD model mice, more than 90% of the engrafted cells differentiated into the lineage of mDA neurons, and approximately 15% developed into mature mDA neurons without tumour formation. The grafted PD model mice also demonstrated significantly improved motor functions.

Conclusion

This study suggests that the differentiation protocol for the preparation of mDA progenitors is a promising option for cell therapy in patients with PD.

Differentiation of Midbrain Dopaminergic Neurons from Human iPS Cells

Human-induced pluripotent stem (iPS) cells provide a powerful means for analyzing disease mechanisms and drug screening, especially for neurological diseases, considering the difficulty to obtain live pathological tissue. The midbrain dopaminergic neurons of the substantia nigra are mainly affected in Parkinson's disease, but it is impossible to obtain and analyze viable dopaminergic neurons from live patients. This problem can be overcome by the induction of dopaminergic neurons from human iPS cells. Here, we describe an efficient method for differentiating human iPS cells into midbrain dopaminergic neurons. This protocol holds merit for obtaining a deeper understanding of the disease and for developing novel treatments.

Mutations in CHCHD2 cause α-synuclein aggregation

Mutations in CHCHD2 are linked to a familial, autosomal dominant form of Parkinson’s disease (PD). The gene product may regulate mitochondrial respiratory function. However, whether mitochondrial dysfunction induced by CHCHD2 mutations further yields α-synuclein pathology is unclear. Here, we provide compelling genetic evidence that mitochondrial dysfunction induced by PD-linked CHCHD2 T61I mutation promotes α-synuclein aggregation using brain autopsy, induced pluripotent stem cells (iPSCs) and Drosophila genetics. An autopsy of an individual with CHCHD2 T61I revealed widespread Lewy pathology with both amyloid plaques and neurofibrillary tangles that appeared in the brain stem, limbic regions and neocortex. A prominent accumulation of sarkosyl-insoluble α-synuclein aggregates, the extent of which was comparable to that of a case with α-synuclein (SNCA) duplication, was observed in CHCHD2 T61I brain tissue. The prion-like activity and morphology of α-synuclein fibrils from the CHCHD2 T61I brain tissue were similar to those of fibrils from SNCA duplication and sporadic PD brain tissues. α-Synuclein insolubilization was reproduced in dopaminergic neuron cultures from CHCHD2 T61I iPSCs and Drosophila lacking the CHCHD2 ortholog or expressing the human CHCHD2 T61I. Moreover, the combination of ectopic α-synuclein expression and CHCHD2 null or T61I enhanced the toxicity in Drosophila dopaminergic neurons, altering the proteolysis pathways. Furthermore, CHCHD2 T61I lost its mitochondrial localization by α-synuclein in Drosophila. The mislocalization of CHCHD2 T61I was also observed in the patient brain. Our study suggests that CHCHD2 is a significant mitochondrial factor that determines α-synuclein stability in the etiology of PD.

NDP52 interacts with mitochondrial RNA poly(A) polymerase to promote mitophagy

Parkin-mediated mitophagy is a quality control pathway that selectively removes damaged mitochondria via the autophagic machinery. Autophagic receptors, which interact with ubiquitin and Atg8 family proteins, contribute to the recognition of damaged mitochondria by autophagosomes. NDP52, an autophagy receptor, is required for autophagic engulfment of damaged mitochondria during mitochondrial uncoupler treatment. The N-terminal SKICH domain and C-terminal zinc finger motif of NDP52 are both required for its function in mitophagy. While the zinc finger motif contributes to poly-ubiquitin binding, the function of the SKICH domain remains unclear. Here, we show that NDP52 interacts with mitochondrial RNA poly(A) polymerase (MTPAP) via the SKICH domain. During mitophagy, NDP52 invades depolarized mitochondria and interacts with MTPAP dependent on the proteasome but independent of ubiquitin binding. Loss of MTPAP reduces NDP52-mediated mitophagy, and the NDP52-MTPAP complex attracts more LC3 than NDP52 alone. These results indicate that NDP52 and MTPAP form an autophagy receptor complex, which enhances autophagic elimination of damaged mitochondria.

Heparan sulfate alterations in extracellular matrix structures and fibroblast growth factor-2 signaling impairment in the aged neurogenic niche

Adult neurogenesis in the subventricular zone of the lateral ventricle decreases with age. In the subventricular zone, the specialized extracellular matrix structures, known as fractones, contact neural stem cells and regulate neurogenesis. Fractones are composed of extracellular matrix components, such as heparan sulfate proteoglycans. We previously found that fractones capture and store fibroblast growth factor 2 (FGF-2) via heparan sulfate binding, and may deliver FGF-2 to neural stem cells in a timely manner. The heparan sulfate (HS) chains in the fractones of the aged subventricular zone are modified based on immunohistochemistry. However, how aging affects fractone composition and subsequent FGF-2 signaling and neurogenesis remains unknown. The formation of the FGF-fibroblast growth factor receptor-HS complex is necessary to activate FGF-2 signaling and induce the phosphorylation of extracellular signal-regulated kinase (Erk1/2). In this study, we observed a reduction in HS 6-O-sulfation, which is critical for FGF-2 signal transduction, and failure of the FGF-2-induced phosphorylation of Erk1/2 in the aged subventricular zone. In addition, we observed increased HS 6-O-endo-sulfatase, an enzyme that may be responsible for the HS modifications in aged fractones. In conclusion, the data revealed that heparan sulfate 6-O-sulfation is reduced and FGF-2-dependent Erk1/2 signaling is impaired in the aged subventricular zone. HS modifications in fractones might play a role in the reduced neurogenic activity in aging brains.

Perlecan is required for the chondrogenic differentiation of synovial mesenchymal cells through regulation of Sox9 gene expression

We previously reported that perlecan, a heparan-sulfate proteoglycan (Hspg2), expressed in the synovium at the cartilage-synovial junction, is required for osteophyte formation in knee osteoarthritis. To examine the mechanism underlying this process, we examined the role of perlecan in the proliferation and differentiation of synovial mesenchymal cells (SMCs), using a recently established mouse synovial cell culture method. Primary SMCs isolated from Hspg2^-/- -Tg (Hspg2^-/- ;Col2a1-Hspg2^Tg/- ) mice, in which the perlecan-knockout was rescued from perinatal lethality, lack perlecan. The chondrogenic-, osteogenic-, and adipogenic-potentials were examined in the Hspg2^-/- -Tg SMCs compared to the control SMCs prepared from wild-type Hspg2^+/+ -Tg (Hspg2^+/+ ;Col2a1-Hspg2^Tg/- ) littermates. In a culture condition permitting proliferation, both control and Hspg2^-/- -Tg SMCs showed similar rates of proliferation and expression of cell surface markers. However, in micromass cultures, the cartilage matrix production and Sox9 and Col2a1 mRNA levels were significantly reduced in Hspg2^-/- -Tg SMCs, compared with control SMCs. The reduced level of Sox9 mRNA was restored by the supplementation with exogenous perlecan protein. There was no difference in osteogenic differentiation between the control and Hspg2^-/- -Tg SMCs, as measured by the levels of Runx2 and Col1a1 mRNA. The adipogenic induction and PPARγ mRNA levels were significantly reduced in Hspg2^-/- -Tg SMCs compared to control SMCs. The reduction of PPARγ mRNA levels in Hspg2^-/- -Tg SMCs was restored by supplementation of perlecan. Perlecan is required for the chondrogenic and adipogenic differentiation from SMCs via its regulation of the Sox9 and PPARγ gene expression, but not for osteogenic differentiation via Runx2. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:837-846, 2017.

Identification of peptides derived from the C-terminal domain of fibulin-7 active for endothelial cell adhesion and tube formation disruption

Despite the research done on pathological angiogenesis, there is still a need for the development of new therapies against angiogenesis-related diseases. Fibulin-7 (Fbln7) is a member of the extracellular matrix fibulin protein family. The Fbln7 C-terminal fragment, Fbln7-C, binds to endothelial cells and inhibits their tube formation in culture. In this study, we screened 12 synthetic peptides, covering the fibulin-globular domain of Fbln7-C, to identify active sites for endothelial cell adhesion and in vitro antiangiogenic activity. Three peptides, fc10, fc11, and fc12, promoted Human Umbilical Vein Endothelial Cells (HUVECs) adhesion, and the morphology of HUVECs on fc10 was similar to that on Fbln7-C. EDTA and the anti-integrin β1 function-blocking antibody inhibited HUVECs adhesion to both fc10 and fc12, and heparin inhibited HUVECs adhesion to both fc11 and fc12. fc10 and fc11 inhibited HUVECs tube formation. Our results suggest that three peptides from Fbln7-C are biologically active for endothelial cell adhesion and disrupt the tube formation, suggesting a potential therapeutic use of these peptides for angiogenesis-related diseases. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 184-195, 2016.

Perlecan inhibits autophagy to maintain muscle homeostasis in mouse soleus muscle

The autophagy-lysosome system is essential for muscle protein synthesis and degradation equilibrium, and its dysfunction has been linked to various muscle disorders. It has been reported that a diverse collection of extracellular matrix constituents, including decorin, collagen VI, laminin α2, endorepellin, and endostatin, can modulate autophagic signaling pathways. However, the association between autophagy and perlecan in muscle homeostasis remains unclear. The mechanical unloading of perlecan-deficient soleus muscles resulted in significantly decreased wet weights and cross-section fiber area compared with those of control mice. We found that perlecan deficiency in slow-twitch soleus muscles enhanced autophagic activity. This was accompanied by a decrease in autophagic substrates, such as p62, and an increase in LC3II levels. Furthermore, perlecan deficiency caused a reduction in the phosphorylation levels of p70S6k and Akt and increased the phosphorylation of AMPKα. Our findings suggested that perlecan inhibits the autophagic process through the activation of the mTORC1 pathway. This autophagic response may be a novel target for enhancing the efficacy of skeletal muscle atrophy treatment.

Perlecan deficiency causes endothelial dysfunction by reducing the expression of endothelial nitric oxide synthase

Perlecan is a major heparan sulfate proteoglycan found in the subendothelial extracellular matrix of the vascular wall. The aim of this study was to investigate the role of perlecan in the regulation of vascular tone. A previously developed conditional perlecan‐deficient mouse model was used to measure changes in the isometric force of isolated aortic rings. The vessels were first precontracted with phenylephrine, and then treated with increasing concentrations of vasorelaxants. Endothelium‐dependent relaxation, elicited by acetylcholine, was significantly reduced in the perlecan‐deficient aortas, whereas endothelium‐independent relaxation caused by the exogenous nitric oxide donor sodium nitroprusside remained well preserved. The expression of the endothelial nitric oxide synthase (eNOS) gene, detected by real‐time polymerase chain reaction, was significantly decreased in the perlecan‐deficient aortas. The expression of eNOS protein detected using Western blotting was also significantly decreased in the perlecan‐deficient aortas. We examined the role of perlecan in eNOS gene expression by creating perlecan knockdown human aortic endothelial cells using small interfering RNA (siRNA) for perlecan. Perlecan gene expression was significantly reduced in the perlecan siRNA‐treated cells, resulting in a significant decrease in eNOS gene expression. Perlecan deficiency induced endothelial dysfunction, as indicated by a reduction in endothelium‐dependent relaxation due, at least partly, to a reduction in eNOS expression. These findings suggest that perlecan plays a role in the activation of eNOS gene expression during normal growth processes.

Perlecan deficiency induced endothelial dysfunction at least partly, to a reduction in eNOS expression. These findings suggest that perlecan plays a role in the activation of the eNOS expression during normal growth processes.

Laminin α1 regulates age-related mesangial cell proliferation and mesangial matrix accumulation through the TGF-β pathway

Laminin α1 (LAMA1), a subunit of the laminin-111 basement membrane component, has been implicated in various biological functions in vivo and in vitro. Although LAMA1 is present in kidney, its roles in the kidney are unknown because of early embryonic lethality. Herein, we used a viable conditional knockout mouse model with a deletion of Lama1 in the epiblast lineage (Lama1(CKO)) to study the role of LAMA1 in kidney development and function. Adult Lama1(CKO) mice developed focal glomerulosclerosis and proteinuria with age. In addition, mesangial cell proliferation was increased, and the mesangial matrix, which normally contains laminin-111, was greatly expanded. In vitro, mesangial cells from Lama1(CKO) mice exhibited significantly increased proliferation compared with those from controls. This increased proliferation was inhibited by the addition of exogenous LAMA1-containing laminin-111, but not by laminin-211 or laminin-511, suggesting a specific role for LAMA1 in regulating mesangial cell behavior. Moreover, the absence of LAMA1 increased transforming growth factor (TGF)-β1-induced Smad2 phosphorylation, and inhibitors of TGF-β1 receptor I kinase blocked Smad2 phosphorylation in both control and Lama1(CKO) mesangial cells, indicating that the increased Smad2 phosphorylation occurred in the absence of LAMA1 via the TGF-β1 receptor. These findings suggest that LAMA1 plays a critical role in kidney function and kidney aging by regulating the mesangial cell population and mesangial matrix deposition through TGF-β/Smad signaling.

A C-terminal fragment of fibulin-7 interacts with endothelial cells and inhibits their tube formation in culture

We have previously demonstrated that fibulin-7 (Fbln7) is expressed in teeth by pre-odontoblast and odontoblast cells, localized in the basement membrane and dentin matrices, and is an adhesion molecule for dental mesenchyme cells and odontoblasts. Fbln7 is also expressed in blood vessels by endothelial cells. In this report, we show that a recombinant C-terminal Fbln7 fragment (Fbln7-C) bound to Human Umbilical Vein Endothelial Cells (HUVECs) but did not promote cell spreading and actin stress fiber formation. Fbln7-C binding to HUVECs induced integrin clustering at cell adhesion sites with other focal adhesion molecules, and sustained activation of FAK, p130Cas, and Rac1. In addition, RhoA activation was inhibited, thereby preventing HUVEC spreading. As endothelial cell spreading is an important step for angiogenesis, we examined the effect of Fbln7-C on angiogenesis using in vitro assays for endothelial cell tube formation and vessel sprouting from aortic rings. We found that Fbln7-C inhibited the HUVEC tube formation and the vessel sprouting in aortic ring assays. Our findings suggest potential anti-angiogenic activity of the Fbln7 C-terminal region.

Perlecan is required for FGF-2 signaling in the neural stem cell niche

In the adult subventricular zone (neurogenic niche), neural stem cells double-positive for two markers of subsets of neural stem cells in the adult central nervous system, glial fibrillary acidic protein and CD133, lie in proximity to fractones and to blood vessel basement membranes, which contain the heparan sulfate proteoglycan perlecan. Here, we demonstrate that perlecan deficiency reduces the number of both GFAP/CD133-positive neural stem cells in the subventricular zone and new neurons integrating into the olfactory bulb. We also show that FGF-2 treatment induces the expression of cyclin D2 through the activation of the Akt and Erk1/2 pathways and promotes neurosphere formation in vitro. However, in the absence of perlecan, FGF-2 fails to promote neurosphere formation. These results suggest that perlecan is a component of the neurogenic niche that regulates FGF-2 signaling and acts by promoting neural stem cell self-renewal and neurogenesis.

Characterization of the molecular interaction between tropoelastin and DANCE/fibulin-5

Fibulin-5 is believed to play an important role in the elastic fiber formation. The present experiments were carried out to characterize the molecular interaction between fibulin-5 and tropoelastin. Our data showed that the divalent cations of Ca(2+), Ba(2+) and Mg(2+) significantly enhanced the binding of fibulin-5 to tropoelastin. In addition, N-linked glycosylation of fibulin-5 does not require for the binding to tropoelastin. To address the fibulin-5 binding site on tropoelastin constructs containing, exons 2-15 and exons 16-36, of tropoelastin were used. Fibulin-5 binding was significantly reduced to either fragment and also to a mixture of the two fragments. These results suggested that the whole molecule of tropoelastin was required for the interaction with fibulin-5. In co-immunoprecipitation experiments, tropoelastin binding to fibulin-5 was enhanced by an increase of temperature and sodium chloride concentration, conditions that enhance the coacervation of tropoelastin. The binding of tropoelastin fragments to fibulin-5 was directly proportional to their propensity to coacervate. Furthermore, the addition of fibulin-5 to tropoelastin facilitated coacervation. Taken together, the present study shows that fibulin-5 enhances elastic fiber formation in part by improving the self-association properties of tropoelastin.

Distinct steps of cross-linking, self-association, and maturation of tropoelastin are necessary for elastic fiber formation

Elastic fibers play an important role in the characteristic resilience of many tissues. The assembly of tropoelastin into a fibrillar matrix is a complex stepwise process and the deposition and cross-linking of tropoelastin are believed to be key steps of elastic fiber formation. However, the detailed mechanisms of elastic fiber assembly have not been defined yet. Here, we demonstrate the relationship between deposition and the cross-linking/maturation of tropoelastin. Our data show that a C-terminal half-fragment of tropoelastin encoded by exons 16-36 (BH) is deposited onto microfibrils, yet we detect very limited amounts of the cross-linking amino acid, desmosine, an indicator of maturation, whereas the N-terminal half-fragment encoded by exons 2-15 (FH) was deficient for both deposition and cross-linking, suggesting that elastic fiber formation requires full-length tropoelastin molecules. A series of experiments using mutant BH fragments, lacking either exon 16 or 30, or a deletion of both exons showed that self-association of tropoelastin polypeptides was an early step in elastic fiber assembly. Immunofluorescence and Western blot assay showed that the treatment of cell culture medium or conditioned medium with beta-aminopropionitrile to inhibit cross-linking, prevented both the deposition and polymerization of tropoelastin. In conclusion, our present results support the view that self-association and oxidation by lysyl oxidase precedes tropoelastin deposition onto microfibrils and the entire molecule of tropoelastin is required for this following maturation process.

Domains 16 and 17 of tropoelastin in elastic fibre formation

Naturally occurring mutations are useful in identifying domains that are important for protein function. We studied a mutation in the elastin gene, 800-3G>C, a common disease allele for SVAS (supravalvular aortic stenosis). We showed in primary skin fibroblasts from two different SVAS families that this mutation causes skipping of exons 16-17 and results in a stable mRNA. Tropoelastin lacking domains 16-17 (Delta16-17) was synthesized efficiently and secreted by transfected retinal pigment epithelium cells, but showed the deficient deposition into the extracellular matrix compared with normal as demonstrated by immunofluorescent staining and desmosine assays. Solid-phase binding assays indicated normal molecular interaction of Delta16-17 with fibrillin-1 and fibulin-5. However, self-association of Delta16-17 was diminished as shown by an elevated coacervation temperature. Moreover, negative staining electron microscopy confirmed that Delta16-17 was deficient in forming fibrillar polymers. Domain 16 has high homology with domain 30, which can form a beta-sheet structure facilitating fibre formation. Taken together, we conclude that domains 16-17 are important for self-association of tropoelastin and elastic fibre formation. This study is the first to discover that domains of elastin play an essential role in elastic fibre formation by facilitating homotypic interactions.

Eosinophil activation in the tissue: synthetic steroid, budesonide, effectively inhibits the survival of eosinophils isolated from peripheral blood but not nasal polyp tissues

We investigated the effect of a potent synthetic steroid, budesonide (BUD), on the survival of nasal polyp (NP) derived eosinophils (EOS). BUD, at the highest dose used, 10(-6) M, decreased this survival but only by approximately one third. We speculated that the relatively small inhibitory effect of budesonide on the survival of NP-EOS could be the result of these EOS being exposed to substantial amounts of GM-CSF, IL-5 or IL-3. In this regard, we detected 148 pg of GM-CSF per 150 mg of tissue, which approximately contained 106 of eosinophils, in the supernatant of NP explants for 24 h without any stimulation. Contents of both IL-5 and IL-3 were much less. We further studied survival of PB-EOS exposed to rhGM-CSF and found that 10(-6) M of BUD could only inhibit by less than one third the survival of PB-EOS exposed to an amount of rhGM-CSF, similar to that detected in the supernatant of NP explants. In addition, we exposed PB-EOS to 200 pg/ml of rhGM-CSF for a relatively long period of time (4 days) in order to mimic chronic exposure in the tissue and found that the survival of these cells was prolonged to the extent similar to that observed in NP-EOS. Our data suggests that the prolonged spontaneous survival of NP-EOS ex vivo is likely the result of sustained in vivo exposure to GM-CSF and budesonide has a smaller inhibitory effect in the survival of these eosinophils as compared to those from peripheral blood.

The distribution of serotonergic nerves in microencephalic rats treated prenatally with methylazoxymethanol

Prenatal exposure of pregnant rats to methylazoxymethanol acetate (MAM) induces microencephaly in the offspring. In the present study of these microencephalic rats (MAM rats) we used quantitative autoradiography to investigate [3H] paroxetine binding sites, which are a selective marker of serotonin (5-HT) transporters (5-HTT). The binding in the accumbens, cortex, hippocampus, and dorsolateral thalamus was significantly increased in MAM rats, compared to the control rats, while there was a significant decrease in the dorsal raphe nucleus of the MAM rats. The levels of 5-HTT mRNA in the dorsal raphe nuclei were analyzed by in situ hybridization, which revealed a significant decrease in 5-HTT mRNA-positive neurons in the MAM rats compared to the control rats. The results imply serotonergic hyperinnervation in the cerebral hemispheres of MAM rats, while a target-dependent secondary degeneration of 5-HT neurons might be induced in the dorsal raphe nuclei of MAM rats.

Dopamine D3 receptor binding by D3 agonist 7-OH-DPAT (7-hydroxy-dipropylaminotetralin) and antipsychotic drugs measured ex vivo by quantitative autoradiography

Because the dopamine D3 receptor is primarily expressed in regions of the limbic system of brain, it was proposed that it may represent a target for antipsychotic drugs that is free of extrapyramidal side effects. An ex vivo receptor binding technique employing [3H]7-OH-DPAT was used to evaluate in vivo occupancy of dopamine D3 receptors in the rat nucleus accumbens by selective D3 agonist 7-OH-DPAT (7-hydroxy-dipropylaminotetralin) and various antipsychotic drugs. With an ID50 value of 0.07 mg/kg, the selective D3 agonist (+)-7-OH-DPAT had the most potent inhibitory effect on ex vivo binding of [3H]7-OH-DPAT among all drugs tested. Clinical doses of phenothiazine drugs, such as chlorpromazine and levomepromazine, induce binding to D3 receptors in vivo, while atypical antipsychotic drugs, such as clozapine, pimozide, and sulpiride, are very weak in inhibiting ex vivo binding of [3H]7-OH-DPAT, indicating that the role of D3 receptors as targets of antipsychotic drugs free of extrapyramidal side effects may not be important.

[Analysis of tympanoplasty at Chiba-Hokuso Hospital, Nippon Medical School]

We evaluated tympanoplasty statistically at Chiba-Hokuso Hospital, a branch hospital of Nippon Medical School. Especially, we discussed the improvement of auditory thresholds after operation, the type of tympanoplasty in valved, the availability of patch tests and complications.

Effect of chronic amitriptyline administration on serotonergic receptors in rats with methylazoxymethanol-induced microencephaly

Methylazoxymethanol (MAM)-induced cortical hypoplasia resulted in a 20% decrease in the Bmax of 5-HT2A receptors in the frontal cortex with no change in the Bmax of 5-HT1A receptors. Chronic treatment with amitriptyline did not further decrease the Bmax of 5-HT2A receptors in the MAM-lesioned cortex, suggesting that the persistent down-regulation of cortical 5-HT2A receptors in MAM-lesioned rats was induced by serotonergic hyperinnervation.

Effects of prenatal methylazoxymethanol treatment on striatal dopaminergic systems in rat brain

To further examine the effects of prenatal methylazoxymethanol (MAM) treatment on striatal dopaminergic systems, the status of presynaptic dopamine transporters was examined by quantitative autoradiography of [3H]GBR 12935 binding. Significantly higher [3H]GBR 12935 binding was seen in MAM-lesioned striatum in comparison to the controls, indicating relative dopaminergic hyperinnervation in MAM-induced hypoplastic striatum. The effect of prenatal MAM treatment on extracellular levels of dopamine and its metabolites in the striatum was also examined using in vivo microdialysis. As measured in conscious freely-moving rats, prenatal MAM treatment significantly increased basal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) release in the striatum in comparison with control rats. These data suggest that in accordance with morphological dopaminergic hyperinnervation, dopaminergic functions are significantly augmented in MAM-lesioned brains. Thus, it is suggested that MAM-induced microencephalic rats should serve as a good animal model for the study of augmented dopaminergic functions in the striatum.

GM-CSF, IL-8, IL-1R, TNF-alpha R, and HLA-DR in nasal epithelial cells in allergic rhinitis

Epithelial cells potentially contribute to airways inflammation by antigen presentation and the production of proinflammatory cytokines. This study investigated the immunocytochemical localization of interleukin-8 (IL-8), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 receptor (IL-1R Type I), tumor necrosis factor-alpha receptor (TNF-alpha R; 55kD), and human leukocyte antigen-DR (HLA-DR) on epithelial cells obtained by nasal brushing from 10 patients with allergic rhinitis in season and 15 healthy, nonallergic subjects. Six of the 15 nonallergic asymptomatic subjects had macroscopic evidence of nasal mucosal inflammation, and their brushings contained more than 10% neutrophils ("subclinical inflammation"). In normal control subjects, 8 +/- 7.5% of epithelial cells stained for HLA-DR, approximately one quarter stained for IL-8 and GM-CSF, and about one third stained positive for IL-1R and TNF-alpha R. The findings in subjects with allergic rhinitis in season and with subclinical neutrophilia were similar, and the numbers of cells staining for HLA-DR expression correlated with both neutrophil and lymphocyte content. These findings further support the conclusion that epithelial cells can contribute to inflammatory processes in the nasal mucosa. The findings emphasize the need to identify asymptomatic nasal mucosal inflammation in studies of the nasal mucosa.

Distinct immunohistochemical localization of IL-4 in human inflamed airway tissues. IL-4 is localized to eosinophils in vivo and is released by peripheral blood eosinophils

Nasal polyposis and asthma are inflammatory conditions of the airways characterized by infiltration of activated inflammatory cells, particularly eosinophils. IL-4 is a multifunctional cytokine considered to play an important role in eosinophilic inflammation. We examined the cellular distribution of immunoreactive IL-4 in nasal polyps, as well as in the bronchial mucosa of both nonasthmatic control subjects (n = 6) and patients with well-characterized mild asthma (n = 6) subjected to a diluent or an allergen challenge. To determine eosinophilic contribution, tissue sections were counterstained with FITC after IL-4 immunostaining. No eosinophils were observed in the bronchial mucosa of nonasthmatic subjects. Nasal polyp tissues contained approximately 15 times more eosinophils per mm2 compared with bronchial tissues from asthmatics after a diluent challenge. Allergen challenge resulted in a marked increase in eosinophil density in bronchial tissues. A negligible number of cells immunostaining IL-4 was observed in bronchial tissues from nonasthmatic control subjects. The density of IL-4-positive cells in nasal polyp tissues was almost three times greater compared with asthmatics bronchial tissues after a diluent challenge. Approximately 90% of the IL-4-positive cells in bronchial tissues did not exhibit fluorescence after FITC counterstaining; in contrast, about 80% of the IL-4-positive cells in nasal polyp tissues did. We also show that peripheral blood eosinophils from allergic subjects express IL-4 mRNA by Northern blot analysis, particularly on stimulation with secretory IgA immune complexes. Finally, the supernatant of stimulated eosinophils contained approximately 50 pg/10(6) cells of IL-4 as determined by ELISA. These data demonstrate that eosinophils express the message and release IL-4 in vitro, and that these cells are the primary source of immunoreactive IL-4 in tissues undergoing chronic severe mucosal inflammation.

Distinct immunohistochemical localization of IL-4 in human inflamed airway tissues. IL-4 is localized to eosinophils in vivo and is released by peripheral blood eosinophils

Nasal polyposis and asthma are inflammatory conditions of the airways characterized by infiltration of activated inflammatory cells, particularly eosinophils. IL-4 is a multifunctional cytokine considered to play an important role in eosinophilic inflammation. We examined the cellular distribution of immunoreactive IL-4 in nasal polyps, as well as in the bronchial mucosa of both nonasthmatic control subjects (n = 6) and patients with well-characterized mild asthma (n = 6) subjected to a diluent or an allergen challenge. To determine eosinophilic contribution, tissue sections were counterstained with FITC after IL-4 immunostaining. No eosinophils were observed in the bronchial mucosa of nonasthmatic subjects. Nasal polyp tissues contained approximately 15 times more eosinophils per mm2 compared with bronchial tissues from asthmatics after a diluent challenge. Allergen challenge resulted in a marked increase in eosinophil density in bronchial tissues. A negligible number of cells immunostaining IL-4 was observed in bronchial tissues from nonasthmatic control subjects. The density of IL-4-positive cells in nasal polyp tissues was almost three times greater compared with asthmatics bronchial tissues after a diluent challenge. Approximately 90% of the IL-4-positive cells in bronchial tissues did not exhibit fluorescence after FITC counterstaining; in contrast, about 80% of the IL-4-positive cells in nasal polyp tissues did. We also show that peripheral blood eosinophils from allergic subjects express IL-4 mRNA by Northern blot analysis, particularly on stimulation with secretory IgA immune complexes. Finally, the supernatant of stimulated eosinophils contained approximately 50 pg/10(6) cells of IL-4 as determined by ELISA. These data demonstrate that eosinophils express the message and release IL-4 in vitro, and that these cells are the primary source of immunoreactive IL-4 in tissues undergoing chronic severe mucosal inflammation.

Triadic discrimination testing: refinement of Thurstonian and sequential sensitivity analysis approaches

The effect of cognitive search strategies and variations in the oral environment on discrimination test performance were investigated. Subjects were required to discriminate between low concentration NaCl solutions and water using the 3-AFC and triangle test protocols. As predicted by Thurstonian modeling, subjects obtained a higher proportion of correct tests for the 3-AFC protocol than for the triangle protocol. The d' values obtained from both protocols corresponded. As predicted by the Sequential Sensitivity Analysis Model, which is largely based on changes in the oral environment, subjects obtained a higher proportion of correct tests for triads containing one NaCl stimulus than for triads containing one water stimulus. Measurement of physical signal strengths of the stimuli, by analysing the Na cation concentration change in the oral environment on tasting, indicated that the classical Thurstone-Ura two-distribution model was insufficient. The strong carry-over effects in the chemical senses require a model based on more than two distributions. It was also noted that subjects did not always use the search strategy required for a given test protocol. The artifactual effects of strategy change during an experiment are discussed.

Interleukin 10 inhibits lipopolysaccharide-induced survival and cytokine production by human peripheral blood eosinophils

In this study we have investigated the effects of interleukin 10 (IL-10) on human peripheral blood eosinophils stimulated with granulocyte/macrophage colony stimulating factor (GM-CSF) and lipopolysaccharide (LPS). We show that LPS was able to enhance eosinophil survival in a dose-dependent manner, as well as release of the cytokines GM-CSF, tumor necrosis factor alpha, and IL-8. LPS-induced eosinophil survival was largely inhibited by an anti-GM-CSF neutralizing antibody and completely blocked by polymyxin B, suggesting GM-CSF involvement in the survival enhancing mechanism and LPS specificity, respectively. IL-10 significantly inhibited survival of, and cytokine production from, eosinophils induced by LPS, but did not inhibit the survival induced by GM-CSF. These observations suggest a novel activation mechanism of eosinophils and, also, that IL-10 may participate in the regulation of diseases characterized by eosinophil infiltration.

[The role of cervical inputs in maintaining equilibrium with regard to age]

The purpose of this experiment is to clarify the role of cervical inputs in maintaining body balance in humans, especially with regard to age. The difference in body sway between with and without neck vibratory stimulation, was analyzed in 83 normal subjects aged 6 to 73. The results showed that the difference between with and without the neck vibratory stimulation was the weakest in those aged from 15 to 44. The difference tended to be stronger in children under 14 years of age and in subjects over 60 years, in contrast to adolescents and nonelderly adults. The neck vibratory stimulation had more effect on forward-backward body sway than on right-left sway, with increasing age. In conclusion, the role of cervical inputs in maintaining equilibrium may change with age, in terms of the quantity and quality of its work capacity function.

Effects of chronic methamphetamine treatment on the binding parameters of [3H]SCH 23390, a selective D1-dopamine receptor ligand, in the rat brain

Following the determination of the binding characteristics of [3H]SCH 23390 using slide-mounted tissue sections of molded minced forebrain, the effects of chronic methamphetamine (MAP) treatment (at a dose of 4 mg/kg for 14 days) on D1 receptors in the rat brain were studied using quantitative receptor autoradiography. There were no differences in both Kd(app) and Bmax values between vehicle- and MAP-treated rats, indicating that D1 receptors might not be involved in the development of behavioral sensitization in chronically MAP-treated rats.

Autosomal dominant type of endosteal hyperostosis with unusual manifestations of sclerosis of the jaw bones

We report three cases of autosomal dominant type endosteal hyperostosis which occurred in one Japanese family. A new pattern of sclerotic changes in the jaw bones is evident. In all members of the family there was a symmetrical thickening of the diaphyseal cortices of the long bones. The affected bones were only minimally widened and the epiphyses and metaphyses were spared. Endosteal sclerosis of the neurocranium was present with loss of the diploë. The sclerotic changes included enlargement and mottled sclerosis of both the maxilla and mandible, with multiple embedded teeth and odontomas. The ramus of the mandible was spared. Severe sclerosis of the jaw bones was present only in a 28-year-old woman. The 2-year-son showed only focal sclerosis in the mandible, and his grandmother had minimal changes in the skeleton.

Time-dependent changes in the binding parameters of muscarinic cholinergic receptors in the rat brain

Using quantitative receptor autoradiography, effects of several incubation times on the binding parameters for [3H]quinuclidinyl benzilate [(3H]QNB) binding were investigated in 5 discrete regions of the rat brain. There were no differences in Bmax-values between 3 incubation times. On the other hand, Kd(app)-values markedly depended on the duration of incubation time. Furthermore, Scatchard plots at low [3H]QNB concentrations showed an abnormal binding behavior, i.e. deviation from the straight line representing a single population of the binding site.

Quantitative autoradiography of muscarinic cholinergic receptors in the rat brain

Using the in vitro autoradiographic technique with tritium-sensitive LKB sheet film and the liquid scintillation counting method, the distribution and the binding parameters of the muscarinic cholinergic receptors (MChR) were determined in various discrete regions of the rat brain. The results obtained in the present study were as follows: (1) Specific binding of [3H]QNB to the slide-mounted tissue sections increased slowly when incubated at room temperature; saturation occurred 2 h after incubation. Only 23% of [3H]QNB bound to the tissue section was dissociated 5 h after the addition of 20 microM atropine to the medium. These findings were very different from those obtained in the study using the tissue homogenates. (2) The regional distribution of MChR was determined using both autoradiographic and liquid scintillation counting methods. The distribution of MChR was heterogeneous, with highest densities in the striatum and nucleus accumbens and lowest in the globus pallidus, nucleus interpeduncularis and nucleus septi. Moreover, MChR were unevenly distributed within the subfields of each region. (3) In saturation binding studies using the slide-mounted tissue sections of 20 micron thickness the (Kd)app-values were similar but not exactly identical in 5 discrete regions, i.e. the striatum, somatosensory cortex, hippocampus (the subiculum + CA1 field), nucleus accumbens and gyrus dentatus, determined in the present study. The (Kd)app-value of each region was about 700 pM which was about 20 times higher than that obtained in the study using the tissue homogenates. However (Kd)app-values obtained with 5 and 10 micron tissue sections were approximately 3-fold lower.