Infective endocarditis after surgical aortic or mitral valve replacement: A nationwide population-based study

OBJECTIVE

Evidence regarding the incidence of prosthetic valve endocarditis and its association with the use of mechanical or biologic prosthetic valves is limited.

METHODS

Patients who underwent aortic or mitral valve replacement in the years 2000 to 2017 were identified from Taiwan's National Health Insurance Research Database and grouped according to the type of prosthesis used (mechanical or biologic). Propensity score matching was performed to reduce confounding.

RESULTS

A total of 22,844 patients were included, with 11,950 (52.2%) and 10,934 (47.8%) in the mechanical prosthesis and biologic prosthesis groups, respectively. After matching, each group contained 5441 patients. During follow-up, patients with a biologic prosthesis had a significantly higher risk of infective endocarditis (IE) than those with a mechanical valve (3.4% vs 1.9%; subdistribution hazard ratio, 1.78; 95% CI, 1.40-2.26). Moreover, biologic prostheses were associated with greater risks of all-cause mortality and redo valve surgery, but lesser risks of ischemic stroke, hemorrhagic stroke, major bleeding, and gastrointestinal bleeding. In subgroup analysis, biologic prostheses were consistently associated with a greater risk of IE in all subgroups, specifically single-valve replacement-aortic, single-valve replacement-mitral, double-valve replacement, active IE (IE diagnosed during index hospitalization), any IE (active or old), and not having a history of IE.

CONCLUSIONS

In this nationwide population-based retrospective cohort study, biologic prosthesis use was associated with a greater risk of IE during follow-up compared with mechanical valve use. However, mechanical valve use was associated with a greater risk of ischemic stroke and hemorrhagic complications.

Identification of 58 novel HLA alleles identified in Chinese individuals by next-generation sequencing

HLA genes are the most polymorphic in the human genome. High resolution HLA typing from 13,870 bone marrow donors in Hong Kong was obtained using Next-generation sequencing (NGS) technology. Among the 67 novel alleles identified, official HLA allele names of 50 novel class I alleles (HLA-A, -B, -C) and 8 novel class II alleles (HLA-DRB1, -DQB1) were assigned by the World Health Organization (WHO) Nomenclature Committee for Factors of the HLA System.

Measurement invariance of the Multidimensional Depression Assessment Scale (MDAS) across gender and ethnic groups of Asian, Caucasian, Black, and Hispanic

BACKGROUND

Major Depressive Disorder is a severe and highly disabling mental illness. Almost all self-reported questionnaires have overlooked the interpersonal symptoms of depression which are important across gender and culture. The Multidimensional Depression Assessment Scale (MDAS) developed by Cheung and Power (2012) entails comprehensive emotional, cognitive, somatic, and interpersonal subscales. It addresses the criticism that existing self-report depression scales might not cover sufficient phenomenological heterogeneity of depression. The current study aimed to evaluate the psychometric properties of the MDAS across gender and four major ethnic groups of Caucasian, Black, Asian and Hispanic, including reliability and concurrent validity against the Centre for Epidemiological Studies Depression Scale (CESD) and Patients Health Questionnaire (PHQ-9). It also aimed to establish a stable factor structure across gender and ethnic groups and test the measurement invariance to enhance its potential for clinical use.

METHODS

A community sample of 3499 participants from four ethnic groups were recruited via online crowdsourcing sites of Qualtrics and Amazon M Turk. Each individual completed a demographic questionnaire, the MDAS, CESD and PHQ-9.

RESULTS

There was good internal consistency (Cronbach's alpha >0.90) and concurrent reliability across gender and ethnic groups. Strict measurement invariance was established for MDAS over a four-factor factor structure corresponding to the four subscales.

CONCLUSIONS

The MDAS showed good psychometric properties and measurement invariance of a four-factor structure, suggesting its potential to be used in clinical settings across gender and ethnic groups.

LIMITATIONS

Participants all answered the questionnaires in English, which could hinder cultural variations in their expression of symptoms.

Effects of dexmedetomidine on surgery for type A acute aortic dissection outcome

No study has evaluated the effect of dexmedetomidine in patients who received surgery for type A aortic dissection. This is the first study to evaluate the effect of dexmedetomidine in aortic dissection patients. This study was executed using data from the Chang Gung Research Database in Taiwan. The CGRD contains the multi‐institutional standardized electronic medical records from seven Chang Gung Memorial hospitals, the largest medical system in Taiwan. We retrospectively evaluate patients who received surgery for acute type A aortic dissection between January 2014 and December 2018. Overall, 511 patients were included, of whom 104 has received dexmedetomidine infusion in the postoperative period. One-to-two propensity score-matching yielded 86 cases in the dexmedetomidine group and 158 cases in the non-dexmedetomidine group. The in-hospital mortality and composite outcome including all-cause mortality, acute kidney injury, delirium, postoperative atrial fibrillation, and respiratory failure, were considered primary outcomes. The in-hospital mortality and composite outcome were similar between groups. The risk of Acute Kidney Injury Network stage 3 acute kidney injury was significantly lower in the dexmedetomidine group than in the non-dexmedetomidine group (8.1% vs 19.0%; OR, 0.38; 95% CI, 0.17–0.86; p = 0.020. The risk of newly-onset dialysis was also significantly lower in the dexmedetomidine group than in the non-dexmedetomidine group (4.7% vs 13.3%; OR, 0.32; 95% CI, 0.11–0.90; p = 0.031). Post-operative dexmedetomidine infusion significantly reduced the rate of severe acute kidney injury and newly-onset dialysis in patients who received surgery for acute type A aortic dissection.

Nationwide cohort study of tricuspid valve repair versus replacement for infective endocarditis

OBJECTIVES

The aim of this study was to compare the outcomes of tricuspid valve (TV) repair versus replacement for patients with infective endocarditis (IE).

METHODS

In this nationwide population-based cohort study, we identified 704 patients from Taiwan National Health Insurance Research Database who underwent TV surgery due to IE between 2000 and 2013. Of them, 412 (58.5%) underwent TV repair and 292 (41.5%) underwent TV replacement, and their perioperative and late outcomes were analysed. Confounding was reduced using the inverse probability of treatment weighting on propensity score.

RESULTS

After inverse probability of treatment weighting, the in-hospital mortality rate between the 2 groups was not significantly different. However, patients who received TV repair had lower rates of perioperative complications, including massive blood transfusion, de novo dialysis and deep wound infection; longer ICU and hospital stays; and higher hospital cost. Regarding late outcomes, TV repair was associated with lower risks of all-cause readmission [subdistribution hazard ratio (HR) 0.68, 95% confidence interval (CI) 0.60-0.78; P < 0.001], readmission for adverse liver outcomes (subdistribution HR 0.75, 95% CI 0.58-0.97; P = 0.025), new permanent pacemaker implantation (subdistribution HR 0.27, 95% CI 0.15-0.48; P < 0.001) and all-cause mortality (HR 0.60, 95% CI 0.51-0.71; P < 0.001) than TV replacement.

CONCLUSIONS

For IE, TV repair is associated with better early and late outcomes than TV replacement. A repair-first strategy is recommended for patients with IE for whom TV surgery is indicated.

CCDC167 as a potential therapeutic target and regulator of cell cycle-related networks in breast cancer

According to cancer statistics reported in 2020, breast cancer constitutes 30% of new cancer cases diagnosed in American women. Histological markers of breast cancer are expressions of the estrogen receptor (ER), the progesterone receptor (PR), and human epidermal growth factor receptor (HER)-2. Up to 80% of breast cancers are grouped as ER-positive, which implies a crucial role for estrogen in breast cancer development. Therefore, identifying potential therapeutic targets and investigating their downstream pathways and networks are extremely important for drug development in these patients. Through high-throughput technology and bioinformatics screening, we revealed that coiled-coil domain-containing protein 167 (CCDC167) was upregulated in different types of tumors; however, the role of CCDC167 in the development of breast cancer still remains unclear. Integrating many kinds of databases including ONCOMINE, MetaCore, IPA, and Kaplan-Meier Plotter, we found that high expression levels of CCDC167 predicted poor prognoses of breast cancer patients. Knockdown of CCDC167 attenuated aggressive breast cancer growth and proliferation. We also demonstrated that treatment with fluorouracil, carboplatin, paclitaxel, and doxorubicin resulted in decreased expression of CCDC167 and suppressed growth of MCF-7 cells. Collectively, these findings suggest that CCDC167 has high potential as a therapeutic target for breast cancer.

In vitro antidermatophytic activity and cytotoxicity of extracts derived from medicinal plants and marine algae

OBJECTIVES

This study was conducted to evaluate the antidermatophytic activity of 48 extracts obtained from medicinal plants (Cibotium barometz, Melastoma malabathricum, Meuhlenbeckia platyclada, Rhapis excelsa, Syzygium myrtifolium, Vernonia amygdalina) and marine algae (Caulerpa sertularioides, Kappaphycus alvarezii) against Trichophyton rubrum and Trichophyton interdigitale (ATCC reference strains), and the cytotoxicity using African monkey kidney epithelial (Vero) cells. Active plant extracts were screened for the presence of phytochemicals and tested against clinical isolates of Trichophyton tonsurans.

METHODS

Six different extracts (hexane, chloroform, ethyl acetate, ethanol, methanol and water) were obtained from each plant or algae sample using sequential solvent extraction. The antidermatophytic activity for the extracts was assessed using a colourimetric broth microdilution method. The viability of Vero cells was measured by Neutral Red uptake assay.

RESULTS

All the extracts (except the water extracts of V. amygdalina, C. sertularioides and K. alvarezii) showed antidermatophytic activity against Trichophyton spp. The minimum fungicidal concentration (MFC) ranges for the plant extracts against T. rubrum and T. interdigitale are 0.0025-2.50 and 0.005-2.50mg/mL, respectively. The algae extracts exhibited lower potency against both species, showing MFC ranges of 0.08-2.50 and 0.31-2.50mg/mL, respectively. The ethanol and methanol extracts from the leaves of R. excelsa, and the methanol and water extracts from the leaves of S. myrtifolium were highly active (MFC<0.1mg/mL) and with high selectivity indices (SI>2.8) against reference strains of T. rubrum and T. interdigitale, and most of the clinical isolates of T. tonsurans. Phytochemical analysis indicates the presence of alkaloids, anthraquinones, flavonoids, saponins, tannins, phenolics and triterpenoids in the extracts.

CONCLUSIONS

The medicinal plant extracts exhibited stronger antidermatophytic activity compared to the algae extracts. The leaves of R. excelsa and S. myrtifolium are potential sources of new antidermatophytic agents against Trichophyton spp.

Derivation of Fate-Committed Schwann Cells from Bone Marrow Stromal Cells of Adult Rats

Our goal is to derive phenotypically stable Schwann cells from bone marrow stromal cells (BMSCs) for use in transplantation studies of central/peripheral nerve injuries. With the adult rat as model, here we describe steps that foster (1) expansion of the BMSC subpopulation of neural progenitors as neurosphere cells, (2) differentiation of the progenitors into Schwann cell-like cells in adherent culture supplemented with soluble factors, and (3) cell-intrinsic switch of Schwann cell-like cells to the Schwann cell fate following co-culture with sensory neurons purified from dorsal root ganglia. The derived Schwann cells retain marker expression despite withdrawal of supplements and neuronal cues, survive passaging and cryopreservation, and, importantly, show functional capacity for myelination.

Identification of the novel HLA-B*39:01:01:04 allele in a Chinese individual by sequence-based typing

The new HLA-B*39:01:01:04 allele differs from HLA-B*39:01:01 by a C → T substitution in intron 1.

HLA-A, -B, -C, and -DRB1 genotyping and haplotype frequencies for a Hong Kong Chinese population of 7595 individuals

HLA-A, -B, -C and -DRB1 gene and haplotype frequencies have been calculated from 7595 southern Chinese unrelated donors in a Hong Kong Bone Marrow Donor Registry. This is the first large-scale paper to report the distribution of A-C-B-DRB1 alleles in Hong Kong Chinese. This information is important for phylogenetic, comparative studies and estimating the optimal and cost-effective donor size and likelihood of obtaining appropriately matched donors for Chinese patients awaiting haematopoietic stem cell transplantation. The allele and haplotype data are available in the Allele Frequencies Net Database under the population name ''Hong Kong Chinese BMDR'' and the identifier (AFND003357).

HLA-A, -B and -DRB1 genotyping and haplotype frequencies of 3892 cord blood units in the Hong Kong Chinese Cord Blood Registry

HLA-A, -B and -DRB1 gene and haplotype frequencies have been calculated from 3892 southern Chinese unrelated cord blood units in a Hong Kong Cord Blood Registry. This is the first large-scale paper to report the distribution of A-B-DRB1 alleles in Hong Kong Chinese Cord Blood Units. This information is important for estimating the optimal and economically cost-effective donor size and likelihood of obtaining appropriately matched cord blood units for Chinese patients awaiting haematopoietic stem cell transplantation. The data are available in the Allele Frequencies Net Database under the population name ''Hong Kong Chinese Cord Blood Registry'' and the identifier (AFND003358).

A metapopulation model with Markovian landscape dynamics

We study a variant of Hanski's incidence function model that allows habitat patch characteristics to vary over time following a Markov process. The widely studied case where patches are classified as either suitable or unsuitable is included as a special case. For large metapopulations, we determine a recursion for the probability that a given habitat patch is occupied. This recursion enables us to clarify the role of landscape dynamics in the survival of a metapopulation. In particular, we show that landscape dynamics affects the persistence and equilibrium level of the metapopulation primarily through its effect on the distribution of a local population's life span.

Identification of a novel HLA-A*02:06:01:02 allele in a Chinese individual by sequence-based typing

The new HLA-A*02:06:01:02 allele differs from HLA-A*02:06:01 by a C→G substitution in Intron 1.

A defensin-like peptide from Phaseolus vulgaris cv. 'King Pole Bean'

A 5447 Da antifungal peptide with an N-terminal sequence highly homologous to plant defensins was purified from Phaseolus vulgaris cv. 'King Pole Bean' by anion-exchange chromatography on Q Sepharose and FPLC-gel filtration on Superdex 75. The isolated peptide inhibited growth of a number of fungal species, including Mycosphaerella arachidicola, Saccharomyces cerevisiae and Candida albicans, with IC(50) values of 3.9, 4.0 and 8.4 μM, respectively. Using the membrane non-permeable DNA-binding dye SYTOX green, it was found that the peptide increased the cell membrane permeability of M. arachidicola, S. cerevisiae and C. albicans.

Increased prospective memory interference in normal and pathological aging: different roles of motor and verbal processing speed

This is a study on prospective memory (PM) and the PM interference effect in normal and pathological aging. One hundred and seven subjects, including 41 healthy young adults, 40 non-demented older adults and 26 patients with mild Alzheimer's disease (AD) participated in this study using a laboratory event-based PM task. PM task performance was comparable between the non-demented older and young adults, but impaired in the AD patients. The PM interference effect increased progressively from the healthy young adults, the non-demented older adults, to the AD patients. Path analysis revealed that the possible mechanism mediating the increased PM interference was the slow motor processing speed in normal aging, while it was the slow verbal speed in pathological aging. It is suggested that different neuropsychological mechanisms may underpin the affected performance of PM task in normal and pathological aging.

Small interfering RNA specific for N-methyl-D-aspartate receptor 2B offers neuroprotection to dopamine neurons through activation of MAP kinase

In the present study, N-methyl-D-aspartate receptor 2B (NR2B)-specific siRNA was applied in parkinsonian models. Our previous results showed that reduction in expression of N-methyl-D-aspartate receptor 1 (NR1), the key subunit of N-methyl-D-aspartate receptors, by antisense oligos ameliorated the motor symptoms in the 6-hydroxydopamine (6-OHDA)-lesioned rat, an animal model of Parkinson's disease (PD).

Neuroprotective effects of neurokinin receptor one in dopaminergic neurons are mediated through Akt/PKB cell signaling pathway

Neurokinin one (NK1) receptor is Substance P (SP) receptor and it is abundantly distributed in the basal ganglia. Growing evidences were shown on their possible roles in the pathogenesis and treatment of Parkinson's disease (PD). NK1 receptor is a kind of G-protein-coupled-receptor (GPCR) and it links to various downstream survival signaling pathways. In the present study, treatment of NK1 receptor agonist septide [(Pyr6, Pro9)-SP (6-11)] was found to ameliorate the motor deficit in 6-hydroxydopamine (6-OHDA) lesioned rats in apomorphine rotation test. Septide treatments were also demonstrated to provide neuroprotection. In 6-OHDA lesioned rats, protection of TH immunoreactive neurons and terminals in substantia nigra (SN) and striatum was found after septide treatment. In SH-SY5Y cultures, cytotoxicity of 6-OHDA was reduced by septide pretreatment. In addition, up-regulations of phosphorylated serine-threonine kinase Akt and phosphorylated mitochondrial apoptotic protein BAD were observed in both in vivo and in vitro models, indicating the inhibition of apoptotic pathway by septide. In conclusion, septide could trigger the pro-survival Akt/PKB signaling pathway and protect dopaminergic neurons in in vivo and in vitro models against 6-OHDA toxicity. Therefore septide treatment may have therapeutic implications in treatment of PD.

Purification and characterization of a lectin from the Indian cultivar of French bean seeds

A lectin specific for glucuronic acid and galacturonic acid has been isolated from seeds of the French bean Phaseolus vulgaris using a procedure that involved affinity chromatography on Affi-gel blue gel, fast protein liquid chromatography (FPLC)-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 200. The lectin was comprised of two 32-kDa subunits with substantial N-terminal sequence similarity to other Phaseolus lectins. The hemagglutinating activity of the lectin was stable within the pH range of 1-13 and the temperature range of 10-60 degrees C. The lectin neither exhibited any antiproliferative activity against tumor cells nor stimulated nitric oxide production by murine peritoneal macrophages at doses as high as 1mM, The lectin failed to evoke any mitogenic response from murine splenocytes as measured by [(3)H-methyl]-thymidine incorporation and did not inhibit the activity of HIV-1 reverse transcriptase. The lectin had no antifungal activity.

Extracorporeal shockwave for hip necrosis in systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) frequently received corticosteroid therapy, resulting in osteonecrosis of the femoral head (ONFH). Prior studies demonstrated the effectiveness of extracorporeal shockwave treatment (ESWT) for ONFH.. This study evaluated the effectiveness of ESWT for ONFH in patients with SLE. We studied 39 patients, including 15 patients with SLE (26 hips) and 24 controls (29 hips). To each affected hip we applied ESWT (6000 impulses at 28 kV in a single session). Patients were ambulated with partial weight bearing for 4-6 weeks. The primary endpoint was the need for hip replacement. The secondary endpoints were improvement in hip pain and function and image changes on X-ray and MRI. Patients received total hip replacement in 12% of patients with SLE and in 14% of controls (P = 0.802). There was no statistically significant difference in pain scores (0.86 vs. 0.89; P = 0.467) and function scores (89% vs. 91%; P = 0.194) between patients with SLE and controls. SLE response to ESWT for ONFH is comparable with ONFH in patients without SLE.

5-HT excites globus pallidus neurons by multiple receptor mechanisms

Anatomical and neurochemical studies indicated that the globus pallidus receives serotonergic innervation from raphe nuclei but the membrane effects of 5-HT on globus pallidus neurons are not entirely clear. We address this question by applying whole-cell patch-clamp recordings on globus pallidus neurons in immature rat brain slices. Under current-clamp recording, 5-HT depolarized globus pallidus neurons and increased their firing rate, an action blocked by both 5-HT(4) and 5-HT(7) receptor antagonists and attributable to an increase in cation conductance(s). Further experiments indicated that 5-HT enhanced the hyperpolarization-activated inward conductance which is blocked by 5-HT(7) receptor antagonist. To determine if 5-HT exerts any presynaptic effects on GABAergic and glutamatergic inputs, the actions of 5-HT on synaptic currents were studied. At 10 microM, 5-HT increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) but had no effect on both the frequency and amplitude of miniature inhibitory postsynaptic currents (mIPSCs). However, 5-HT at a higher concentration (50 microM) decreased the frequency but not the amplitude of the mIPSCs, indicating an inhibition of GABA release from the presynaptic terminals. This effect was sensitive to 5-HT(1B) receptor antagonist. In addition to the presynaptic effects on GABAergic neurotransmission, 5-HT at 50 microM had no consistent effects on glutamatergic neurotransmission, significantly increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in 4 of 11 neurons and decreased the frequency of mEPSCs in 3 of 11 neurons. In conclusion, we found that 5-HT could modulate the excitability of globus pallidus neurons by both pre- and post-synaptic mechanisms. In view of the extensive innervation by globus pallidus neurons on other basal ganglia nuclei, this action of 5-HT originated from the raphe may have a profound effect on the operation of the entire basal ganglia network.

Removal of phenylurea herbicide monuron via riboflavin-mediated photosensitization

Photodegradation of the phenylurea herbicide monuron by using riboflavin (Rf), a sensitizer, was investigated by varying the doses of monuron and Rf in this work. An enhanced photochemical effect was observed in the process compared with the direct photolysis by using UV irradiation only. The reaction time was greatly shortened from more than 60 min (direct photolysis) to 8-30 min depending on the doses of initial concentration of monuron ([M]0) and Rf. A modified hyperbola model was found to be useful to determine the reaction kinetics and thereafter the performance on the photodegradation of monuron sensitized by Rf. Two measurable characteristic constants (initial decay rate and total removal index) were used to quantify the reaction. The maximum removal difference compared with the direct photolysis and Rf-sensitization was investigated. It was found that the improvement of the process depended on both the [M]0 and the doses of Rf.

Effects of hyperbaric oxygen and platelet derived growth factor on medial collateral ligament fibroblasts

PURPOSE

This study investigated hyperbaric oxygen (HBO2) and platelet-derived growth factor-BB (PDGF-BB) to determine their combined effects on fibroblasts from rabbit medial collateral ligament (MCL).

METHOD

Cells were divided into four groups: (I) Control, (II) HBO2 treatment, (III) PDGF-BB treatment and (IV) HBO2 combined with PDGF-BB treatment. All hyperoxic cells were exposed to 100% O2 at 2.5 atmospheres absolute (ATA) in a hyperbaric chamber for 120 minutes per 48 hours. Measurement of cell growth was based on increase in cell number. Cell cycle modulations were analyzed by fluorescence-activated cell sorter (FACS). Quantity of Type I and Type III collagen was determined by western blotting and image analyzer.

RESULTS

Treatment doses of HBO2 alone or PDGF-bb alone dependently increased cell growth. A combination of HBO2 treatment plus PDGF-bb treatment had an additive effect on cell growth in comparison with HBO2 treatment alone or PDGF-bb treatment alone. FACS analysis revealed that HBO2 alone, PDGF-bb alone and PDGF-bb plus HBO2 treatment increase the percentage of cells accumulated in S-phase. Western blotting analysis revealed that Type III collagen content was decreased significantly after HBO2 treatment alone or HBO2 plus PDGF-bb treatment but not in PDGF-bb treatment alone. In contrast, although Type I collagen content was increased after HBO2 treatment, the increase in Type I collagen (increase /original) was not statistically significant.

CONCLUSION

HBO2 or HBO2 plus PDGF-bb treatment decreases the Type III collagen/Type I collagen content, which could result in mechanically stronger collagen fibrils. We propose HBO2 therapy as a potentially effective treatment for MCL healing.

Up-regulation in expression of vesicular glutamate transporter 3 in substantia nigra but not in striatum of 6-hydroxydopamine-lesioned rats

Overactivity of the glutamatergic system is suggested to be closely related to the onset and pathogenesis of Parkinson's disease. Vesicular glutamate transporters (VGLUT1, T2 and T3) are a group of glutamate transporters in neurons that are responsible for transporting glutamate into synaptic vesicles and they are key elements for homeostasis of glutamate neurotransmission. The present study was aimed to investigate the expression of VGLUT1, T2 and T3 proteins after the onset of Parkinson's disease. A rat model of Parkinson's disease, the 6-hydroxydopamine-lesioned rat, was employed. Immunocytochemistry revealed that VGLUT1, T2 and T3 immunoreactivity was not modulated in the striatum of the lesioned rat. Western blotting analyses also showed that there was no change in the expression of T1, T2 and T3 proteins in the striatum. In contrast, no VGLUT1 protein was detected in the substantia nigra. After the lesion, levels of VGLUT2 immunoreactivity and protein were not modulated. Significant increase of VGLUT3 immunoreactivity was observed in the perikarya of GABAergic substantia nigra pars reticulata neurons (+14.7%) although VGLUT3 protein was not modulated in the nigral tissues. VGLUT3 in GABAergic neurons is suggested to play a role in GABA synthesis. The present results may therefore implicate that VGLUT1 and T2 are not modulated in the striatum and the substantia nigra of the 6-hydroxydopamine-lesioned rat and only VGLUT3 plays a role in pathogenesis of Parkinson's disease.

Neuroprotective effects of ginsenoside-Rg1 in primary nigral neurons against rotenone toxicity

Ginsenoside-Rg1, the pharmacologically active component isolated from ginseng, demonstrated neuroprotective effects on primary cultured rat nigral neurons against rotenone toxicity. Rotenone, a common household pesticide known for its specific and irreversible mitochondria complex I inhibition, has been suggested to be the causal agent of Parkinson's disease (PD) by inducing degeneration of cells in the substantial nigra. The present study demonstrated that co-treatment of rotenone and Rg1 could reduce rotenone-induced cell death by 58% (SEM=+/-5.60; N=3). Rotenone-induced mitochondria membrane potential (MMP, DeltaPsim) depletion was restored and elevated by at least 38% (SEM=+/-2.15; N=3) by Rg1. In addition, Rg1 prevented cytochrome c release from the mitochrondrial membrane and increased the phosphorylation inhibition of the pro-apoptotic protein Bad through activation of the PI3K/Akt pathway. The protective effects of Rg1 was blocked by glucocorticoid receptor antagonist RU486, indicating that the action of Rg1 is mediated through glucocorticoid receptor (GR). In conclusion, Rg1 inhibits the mitochondrial apoptotic pathway and increases the survival chance of the primary cultured nigral neurons against rotenone toxicity. Thus, Rg1 and its related compounds may be developed as protective agents against neurodegenerative diseases induced by mitochondrial toxins.

Ablation of gene expression of N-methyl-D-aspartate receptor one by antisense oligonucleotides in striatal neurons in culture

In the present study, a twenty-mer antisense oligonucleotide specific for N-methyl-D-aspartate receptor one (ANR1) was applied to striatal neurons in primary cell culture. The ANR1 was found to be specific and nontoxic. Significant reductions in expression of NR1 mRNA and proteins were resulted after a single dose of ANR1 transcripts. Interestingly, there were reductions in total NR1 proteins but two phosphorylated forms of NR1 proteins at serine 896 and 897 residues were not reduced. There was also no change in the pattern of distribution of NR1 immunoreactivity in the striatal neurons. In addition, significant reductions of NMDA-mediated peak inward current were found after application of a higher concentration of ANR1 (20-100 microM) by patch clamp recordings. The present results indicate that ANR1 is a useful agent in reducing NMDA receptor functions. The present data thus provide detailed cellular and molecular mechanisms to explain our previous findings of amelioration of motor symptoms in a rat model of Parkinson's disease. More importantly, application of ANR1 was also found to display neuroprotective effects of striatal neurons against NMDA-induced excitotoxic cell death. The findings have implications in development of new approach in prevention of cell death in neurodegenerative diseases and new treatments for these diseases.

Age-related differences in response regulation as revealed by functional MRI

This fMRI study studied age-related differences in neural activities during response regulation. Twenty-one male participants from two age groups, a younger group and an older group (mean ages: 29.9 and 65.2 years, respectively), were scanned while performing a task with response compatibility manipulation. They were presented with a sequence of arrowheads that pointed either upward or downward. In the "Response Compatible" condition, they were required to press an up or a down button consistent with the direction of the arrowhead. In the "Response Incompatible" condition, they were required to press the button opposite to the arrowhead direction so that an upward arrow should elicit a down response, and vice versa. Findings showed age-related differences in response regulation in several brain regions, including the right frontal, the right cingulate, and the left inferior parietal cortexes. The findings suggested a higher level of neural activity in the right prefrontal and left inferior parietal regions during response regulation for the older adults than for the younger adults.

Tyrosine kinase receptor immunoreactivity in trigeminal mesencephalic and motor neurons following transection of masseteric nerve of the rat

Neurotrophins are known to promote survival after neural injury. To determine the relative importance of tyrosine kinase receptors on the survival of axotomized trigeminal nuclear neurons, we examined the temporal expression profile of tyrosine kinase A, tyrosine kinase B and tyrosine kinase C receptors in the mesencephalic trigeminal nucleus and the motor trigeminal nucleus following transection of the masseteric nerve in rats. Axotomized neurons in these nuclei were retrogradely identified with FluoroGold. We found increase in tyrosine kinase A-immunoreactive mesencephalic trigeminal nucleus neurons in the second week after axotomy but no change in the number of tyrosine kinase A-immunoreactive motor trigeminal nucleus neurons. There was no change in the number of tyrosine kinase B-immunoreactive mesencephalic trigeminal nucleus neurons but the significant increase of tyrosine kinase B-immunoreactive motor trigeminal nucleus neurons throughout the period of observation (3 weeks) peaked at approximately 1 week after axotomy. There was no alteration in the number of tyrosine kinase C-immunoreactive mesencephalic trigeminal nucleus neurons but significant increase in tyrosine kinase C-immunoreactive motor trigeminal nucleus neurons observable by 4 days post-axotomy was followed by decline to levels lower than the control in 2 weeks. Temporal changes in the expression of individual tyrosine kinase receptors in mesencephalic trigeminal nucleus and motor trigeminal nucleus neurons following transection of the masseteric nerve suggest differential contribution of tyrosine kinase-specific neurotrophins to the survival of these neurons after axotomy.

Differential expression of NMDA and AMPA/KA receptor subunits in the inferior olive of postnatal rats

We have employed immunohistochemistry to determine the expression patterns of receptor subunits of N-methyl-d-aspartate (NMDA-NR1 and NR2A/B) and alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid/kainic acid (AMPA/KA-GluR1, GluR2, GluR2/3, GluR4, and GluR5/6/7) in the inferior olive of postnatal rats up to adulthood. Immunoreactivity for distinct receptor subunits was predominantly localized in the soma and dendrites of neurons. Semi-quantification showed that the overall immunoreactivity in the inferior olive of adults was intense for GluR1, moderate for NR1 and NR2A/B, and low for GluR2, GluR2/3, GluR4, and GluR5/6/7. At P7, GluR1 was restricted to the dorsomedial cell column, subnucleus beta, principal nucleus and ventrolateral protrusion while the other subunits were found in all subnuclei of the inferior olive. The immunoreactivities for all glutamate receptor subunits ranged from low to moderate. As the rats matured, the immunoreactivity of GluR4 decreased after the second postnatal week, while those of the other subunits showed a general trend of increase, reaching adult level during the third postnatal week. Double immunofluorescence revealed that all NR1-containing neurons exhibited NR2A/B immunoreactivity, indicating that native NMDA receptors comprise of hetero-oligomeric combinations of NR1 and NR2A/B. Furthermore, co-localization of NMDA and AMPA/KA receptor subunits was demonstrated in individual neurons of the inferior olive. All NR1-containing neurons exhibited GluR1 immunoreactivity, and all NR2A/B-containing neurons showed GluR5/6/7 immunoreactivity. Our data suggest that NMDA and AMPA/KA receptors are involved in glutamate-mediated neurotransmission, contributing to synaptic plasticity and reorganization of circuitry in the inferior olive during postnatal development.

Expression of Trk receptors in otolith-related neurons in the vestibular nucleus of rats

The expression of the three Trk receptors (TrkA, TrkB, and TrkC) in otolith-related neurons within the vestibular nuclei of adult Sprague-Dawley rats was examined immunohistochemically. Conscious animals were subjected to sinusoidal linear acceleration along either the anterior-posterior (AP) or interaural (IA) axis on the horizontal plane. Neuronal activation was defined by Fos expression in cell nuclei. Control animals, viz labyrinthectomized rats subjected to stimulation and normal rats that remained stationary, showed only a few sporadically scattered Fos-labeled neurons. Among experimental rats, the number of Fos-labeled neurons and their distribution pattern in each vestibular subnucleus in animals stimulated along the antero-posterior axis were similar to those along the interaural axis. No apparent topography was observed among neurons activated along these two directions. Only about one-third of the Trk-immunoreactive neurons in the vestibular nucleus expressed Fos. Double-labeled Fos/TrkA, Fos/TrkB and Fos/TrkC neurons constituted 85-98% of the total number of Fos-labeled neurons in vestibular nuclear complex and its subgroups x and y. Our findings suggest that Trk receptors and their cognate neurotrophins in central otolith neurons may contribute to the modulation of gravity-related spatial information during horizontal head movements.

Inhibition of nitric oxide can ameliorate apoptosis and modulate matrix protein gene expression in bacteria infected chondrocytes in vitro

Bacterial infection stimulates nitric oxide (NO) production in chondrocytes. However, the role of NO in chondrocyte apoptosis after infection remains unclear. The purpose of the study was to test if inhibition of NO could ameliorate apoptosis and modulate matrix protein gene expression in bacteria-infected chondrocytes. It was shown that pre-treating chondrocytes with L-NAME (1 mM) significantly decreased the release of NO (from 72 to 14 microM) and the extent of apoptosis (from 52.9% to 18.9%). Pre-treatment with L-NAME also counteracted the bacteria-induced downregulation of Type II collagen (from 26% to 79%) and aggrecan (from 63% to 105%) mRNA levels. Inhibition of NO after the induction of infection could not decrease the extent of apoptosis and modulate matrix protein gene expression. The results of this study support the hypothesis that NO has an important role in bacteria-induced chondrocyte apoptosis. Pre-treatment but not post-treatment could ameliorate the extent of apoptosis and reestablish the cartilage matrix protein gene expression. This study suggests that in addition to NO, other mechanisms may be responsible for the sustained destruction of articular cartilage in the post-infectious arthropathy.

The first batch of graduates of a new medical curriculum in Asia: how their teachers see them

OBJECTIVE

To examine teachers' views of the first batch of graduates of a revised medical curriculum in Asia.

METHODS

A cross-sectional study using a structured questionnaire was carried out to obtain the views of all the clinical teachers involved in teaching final year students of the old curriculum in 2000-01 and the new curriculum in 2001-02 at the University of Hong Kong, which commenced curricular reform in 1997.

RESULTS

Nearly 62% of respondents felt that better graduates were being produced with the new curriculum. The majority of them rated the new curriculum students better in nearly all the major goals of the new curriculum, such as self-directed learning initiative, problem solving skills, interpersonal skills and clinical performance in patient care. However, the core knowledge of the new curriculum students was of concern to some teachers.

CONCLUSION

This study focused on the first complete cycle of a revised medical curriculum in Asia. Teachers' views of the new curriculum students were highly positive and they felt that better graduates were being produced.

Differential expression of AMPA receptor subunits in substance P receptor-containing neurons of the caudate-putamen of rats

Previous evidence has suggested that glutamate-driving neurotransmission and glutamate-excitotoxicity are modulated by substance P in the basal ganglia, but the assembly of glutamate receptors mediating this process remains to be delineated. By using a double immunofluorescence, cellular expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor subunits (GluR1-4) in substance P receptor (SPR)-containing neurons was examined in the striatum of rats. It revealed that distribution of SPR-immunoreactive neurons completely overlapped with that of GluR1, 2, 3 or 4-immunoreactive neurons in the caudate-putamen. Neurons showing both SPR and AMPA receptor subunits (except of GluR3)-immunoreactivity were observed: all (100%) of SPR-positive neurons displayed GluR1-, GluR2- or GluR4-immunoreactivity, and the double-labeled neurons constituted about 33, 3 or 29% of total GluR-positive ones. In contrast, the neurons exhibiting both SPR- and GluR3-immunoreactivity were not detected, though numerous GluR3-positive neurons were still distributed in the caudate-putamen regions. Co-localization of SPR and distinct AMPA receptor subunits in the striatal neurons has provided a basis for functional modulation of neuronal APMA receptors by substance P in the caudate-putamen of rodents. Taken together with previous observations, this study has also suggested that, through interaction with AMPA receptors composed of subunits 1, 2 and 4, substance P or neurokinin peptides may play important roles in regulating neuronal properties and protecting neurons from excitotoxicity in the basal ganglia of mammals.

Selective knockdown of gene expression of N-methyl-D-aspartate receptor one ameliorates parkinsonian motor symptom in 6-hydroxydopamine-lesioned rats

The present study reported the efficacy of antisense oligonucleotides specific for N-methyl-D-aspartate receptor one (NR1) in reduction of motor symptom in a rat parkinsonian model, the unilateral 6-hydroxydopamine-lesioned rat. Significant reductions in apomorphine-induced contralateral rotation were only seen in the NR1 antisense-treated lesioned rats (after a single intraparenchymal dose of antisense to the lesioned neostriatum; 15 nmol in 3 microl of saline) at 1 or 2 days after the treatment. No motor effect was seen in the lesioned animals with control treatments (sham, treatment using NR1 sense oligonucleotides, randomized oligonucleotides or saline, respectively). In contrast, significant increases in expression of NR1 mRNA in the lesioned neostriatum were seen in rats with control treatments but not in rats with NR1 antisense treatment. Importantly, in the lesioned neostriatum that was treated with NR1 antisense, a significant reduction in NR1 protein expression was found and NR1 immunoreactivity was seen to reduce in perikarya of presumed striatal medium spiny neurons. The present data indicate that a single dose of NR1 antisense ameliorates motor symptom in the rat model. The efficacy of NR1 antisense is likely to be mediated by a selective knockdown in expression of NR1 mRNA and proteins in the presumed medium spiny neurons.

Neurokinin peptides and neurokinin receptors as potential therapeutic intervention targets of basal ganglia in the prevention and treatment of Parkinson's disease

Parkinson's disease (PD) is a serious motor disorder and it is the second most common brain degenerative disease in human. PD is known to be caused by degeneration of dopamine neurons in the substantia nigra but the cause of cell death is largely unknown. Mammalian neurokinins [NKs] are a group of neuropeptides that include substance P (SP; neurokinin-1, NK-1), substance K (SK; NK-2; neurokinin A), and neuromedin K (NK; NK-3; neurokinin B). Their biological effects as neurotransmitters, neuromodulators, or neurotrophic-like factors are mediated by three distinct neurokinin receptors, namely SP receptor (SPR: NK-1 receptor, NK-1R), SKR (NK-2R), and NKR (NK-3R). Several lines of evidence have indicated that neurokinins are implicated in the pathogenesis of PD. First, decreases of SP level and SP-immunoreactivity have been found in nigral and striatal tissues of animals with PD and postmortem PD patients. Second, NKs exert neuroprotective effects on neurons. In addition, NK receptors, namely NK-1 and NK-3 receptors, are abundantly localized in dopaminergic and cholinergic neurons of the basal ganglia, indicating that these neurons are under the physiological regulation of NKs. Moreover, modulation in motor activity occurred in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice, PD animal model, after systemic administration of NK receptor agonists. NKs and NK receptors, therefore, might be important molecules that are associated with functions and survival of neurons in the basal ganglia, in particular the dopamine neurons. Further studies should be devoted to elucidate the functional roles of NK systems in (a) the neuropathogenesis and neuroprotection during the course of PD, (b) the efficacy of NK receptor drugs towards PD, and (c) potential therapeutic intervention that targets at the prevention or treatment of PD.

Differential expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate glutamate receptors in the rat striatum during postnatal development

Alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA)-type glutamate receptors (GluR1-4) are one of the most important ionotropic glutamate receptors in the striatum, a key region of the basal ganglia. The present study investigated the trend of developmental expression of AMPA receptor subunits in the striatum of rats in different developmental stages, i.e., at postnatal day 7 (PND7), PND21 and adult. Perfuse-fixed striatal sections were used. The expression of AMPA subunits was studied by immunofluorescence and reverse transcriptase-polymerase chain reaction (RT-PCR). RT-PCR revealed that the levels of expression of the GluR1 and GluR3 mRNAs were the same among the age groups. The level of GluR2 mRNA was highest in PND21 rats and lowest in adult. The highest level of GluR4 mRNA was detected in rats at PND7. Similar trends of GluR1, GluR2 and GluR2/3 immunoreactivity expression were observed using commercially available specific antibodies. In addition, a large proportion of parvalbumin-immunoreactive GABAergic interneurons in the striatum were found to display GluR1 immunoreactivity in PND21 and adult rats. In contrast, most of the choline acetyltransferase-immunoreactive cholinergic interneurons were found to display GluR2 immunoreactivity but less GluR1 and no GluR2/3 immunoreactivity in PND21 and adult rats. The present study suggests that there is a distinct pattern of expression of AMPA-type receptor mRNAs and proteins in the rat striatum at different stages of development.

Clinical profile and genetic basis of Brugada syndrome in the Chinese population

OBJECTIVE

To study the clinical profile and genetic basis of Brugada syndrome in Chinese patients.

DESIGN

Prospective observational study.

SETTING

Seven regional public hospitals, Hong Kong.

MAIN OUTCOME MEASURES

The clinical and follow-up data of 50 patients (47 men, 3 women; mean age, 53 years) were collected, and genetic data of 36 probands and eight family members of three genotyped probands were analysed.

RESULTS

Eight patients survived sudden cardiac death (group A), 12 had syncope of unknown origin but no sudden death (group B), and 30 were asymptomatic before recognition of Brugada syndrome (group C). Programmed electrical stimulation induced sustained ventricular arrhythmias in 88% (7/8), 82% (9/11), and 27% (3/11) of patients in group A, group B, and group C, respectively. New arrhythmic events occurred in 50% (4/8) of patients in group A and 17% (2/12) of patients in group B after a mean follow-up period of 30 (standard deviation, 13) months and 25 (7) months, respectively. All group C patients remained asymptomatic during a mean follow-up period of 25 (standard deviation, 11) months. Five of 36 probands and three of eight family members who underwent genetic testing were found to have a mutation in their SCN5A gene.

CONCLUSIONS

Chinese patients with Brugada syndrome who are symptomatic have a high likelihood of arrhythmia recurrence, whereas asymptomatic patients enjoy a good short-term prognosis. The prevalence of SCN5A mutation among probands is 14%. Thus, Chinese patients with Brugada syndrome share with their western counterparts similar clinical and genetic heterogeneity.

Identification of brain-derived neurotrophic factor in nestin-expressing astroglial cells in the neostriatum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice

Up-regulation of nestin expression was significantly induced in the caudate-putamen of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice in our previous observation [Brain Res 925 (2002) 9]. We hypothesized that the nestin-expressing cells might play an important role in the pathogenesis of parkinsonian model, and characterization of these nestin-expressing cells was studied by RT-PCR, immunohistochemistry and semi-quantitative analysis for various markers of glial fibrillary acid protein (GFAP), S-100, neuronal nuclear specific protein (NeuN), beta-tubulin, Ki-67 and brain-derived neurotrophic factor (BDNF) expression in MPTP-treated C57/BL mice. Firstly, significant increasing in both nestin protein and mRNA was found in MPTP-treated mice. Up-regulation of nestin expression started at day 1, peaked at day 3, and gradually went down at days 7-21 in the neostriatum after MPTP treatment. Secondly, double immunofluorescence indicated that almost all of nestin-positive cells exhibited GFAP (98%) or S-100 (96%)-immunoreactivity, whereas NeuN or beta-tubulin was hardly detected in these nestin-positive cells. Thirdly, a minor population (7.0%) of nestin-positive cells showed Ki-67 (cell proliferation marker)-immunoreactivity, showing some of them went into cell mitotic state. Finally but more interestingly, a major population (86%) of nestin-expressing cells also exhibited immunoreactivity for BDNF, one neurotrophic factor. These results present time-dependent up-regulation of nestin expression in neostriatum, the proliferative and neurotrophic properties of nestin-expressing astroglial cells in MPTP-treated C57/BL mice. Taken together with previous observations, this study suggests that nestin-expressing activated astroglial cells, possibly partially through synthesizing and releasing neurotrophic factors such as BDNF in the basal ganglia, may play important roles in protection of nigrostriatal dopamine neurons and in the pathogenesis of Parkinson's disease in mammals.

Gene expression of glutamate receptors GluR1 and NR1 is differentially modulated in striatal neurons in rats after 6-hydroxydopamine lesion

In the present study, we attempted to address the modulation of the gene expression of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) glutamate receptors in the neostriatum of the 6-hydroxydopamine (6-OHDA)-lesioned rat, an animal model of Parkinson's disease. After 2 weeks of lesion, reverse transcriptase-polymerase chain reactions (RT-PCRs) revealed significant reduction in GluR1 mRNA expression but a significant enhancement of NR1 mRNA expression in the striatal tissues of the lesioned side. No modulation in the mRNA expression of GluR2, GluR3, GluR4 and NR2B were found. Immunofluorescence with digital imaging analysis also demonstrated a significant reduction in GluR1 immunoreactivity in the lesioned neostriatum. Interestingly, the reduction in GluR1 immunoreactivity was primarily observed in presumed striatal medium spiny neurons but not in parvalbumin-labeled striatal GABAergic interneurons. Immunoreactivity for GluR2, GluR2/3, GluR4, NR1 and NR2B was unchanged in neurons of the neostriatum of the lesioned side. The present results indicate that there is an opposite trend in modulation in the gene expressions of GluR1 and NR1 in the neostriatum of 6-OHDA-lesioned rats after dopamine denervation. Modulation of GluR1 mRNA and immunoreactivity is likely to be limited in the striatal projection neurons. These findings have implications for the use of NMDA and AMPA receptor antagonists in the treatment of Parkinson's disease.

Striatal neurons but not nigral dopaminergic neurons in neonatal primary cell culture express endogenous functional N-methyl-d-aspartate receptors

Developmental expression of N-methyl-D-aspartate (NMDA) receptor subunits were determined and compared in striatal and nigral neurons in neonatal primary cell cultures. In striatal neurons, NR1, NR2A and NR2B mRNAs and immunoreactivity, and NR2D mRNA were found and the maximal levels of NR1 mRNA and immunoreactivity expression were found at 6 day-in-vitro (DIV). NMDA receptors found at this stage in striatal neurons are likely to contain NR1 plus NR2A, NR2B and NR2D subunits. In nigral neurons, NR1 and NR2B mRNAs and immunoreactivity, and NR2D mRNA were found and the maximal level of NR1 immunoreactivity expression was found at 10 DIV. Unlike striatal neurons, NMDA receptors found in nigral neurons are likely to contain NR1 plus NR2B and NR2D subunits only. NMDA-induced toxicity assays showed that striatal neurons were most susceptible to cell death at around 10 DIV but nigral neurons were not susceptible to NMDA-induced cell death at all stages. In addition, patch clamp analysis revealed that functional NMDA receptors could only be found in striatal neurons but not in nigral dopaminergic neurons in vitro. The present results indicate that striatal and nigral neurons are programmed to express distinct NMDA receptor subunits during their endogenous development in cell cultures. Despite dopaminergic neurons in culture display NMDA receptor subunits, functional NMDA receptors are not assembled. The present findings have demonstrated that dopaminergic neurons in vitro may behave very differently to their counterparts in vivo in terms of NMDA receptor-mediated responses. Our results also have implications in transplantations using dopaminergic neurons in vitro in treatments of Parkinson's disease.

Chondroitinase ABC enhances axonal regrowth through Schwann cell-seeded guidance channels after spinal cord injury

Grafting of Schwann cell-seeded channels into hemisected adult rat thoracic spinal cords has been tested as a strategy to bridge the injured cord. Despite success in guiding axonal growth into the graft, regeneration across the distal graft-host interface into the host spinal cord was limited. We hypothesized that chondroitin sulfate (CS) glycoforms deposited at the gliotic front of the interface constitute a molecular barrier to axonal growth into the host cord. Because CS glycoforms deposited by purified astrocytes in vitro were removable by digestion with chondroitinase ABC, we attempted to achieve likewise by infusion of the enzyme to the host side of the interface. By 1 month post-treatment, significant numbers of regenerating axons crossed an interface that was subdued in macrophage/microglia reaction and decreased in CS-immunopositivity. The axons extended as far into the caudal cord as 5 mm, in contrast to nil in vehicle-infused controls. Fascicular organizations of axon-Schwann cell units within the regenerated tissue cable were better-preserved in enzyme-treated cords than in vehicle-infused controls. We conclude that CS glycoforms deposited during gliosis at the distal graft-host interface could be cleared by the in vivo action of chondroitinase ABC to improve prospects of axonal regeneration into the host spinal cord.

Receptors of glutamate and neurotrophin in vestibular neuronal functions

The last decade has witnessed advances in understanding the roles of receptors of neurotrophin and glutamate in the vestibular system. In the first section of this review, the biological actions of neurotrophins and their receptors in the peripheral and central vestibular systems are summarized. Emphasis will be placed on the roles of neurotrophins in developmental plasticity and in the maintenance of vestibular function in the adult animal. This is reviewed in relation to the developmental expression pattern of neurotrophins and their receptors within the vestibular nuclei. The second part is focused on the functional role of different glutamate receptors on central vestibular neurons. The developmental expression pattern of glutamate receptor subunits within the vestibular nuclei is reviewed in relation to the potential role of glutamate receptors in regulating the development of vestibular function.

The striatal GABA-ergic neurons expressing substance P receptors in the basal ganglia of mice

By using a double immunofluorescence, we have examined the distribution of striatal GABAergic neurons that expressed substance P receptor (SPR) in the basal ganglia of adult C57 mice. The distribution of GABA-immunoreactive neurons completely or partially overlapped with that of SPR-immunoreactive neurons in the striatum (i.e. the caudate-putamen), globus pallidus, ventral pallidum, and nucleus accumbens. Neurons showing both GABA- and SPR-immunoreactivities were, however, predominantly found in the caudate-putamen, and most of them were characterized by their large-sized aspiny neuronal profile. Semi-quantification indicated that only about 13% of the total GABA-immunoreactive neurons (including large and medium-sized) displayed SPR-immunoreactivity, and these double-labeled neurons constituted about 31% of the total SPR-immunoreactive cells in the striatum. Neurons double-labeled with GABA- and SPR-immunoreactivities were hardly detected in other aforementioned regions of the basal ganglia. In addition, double immunofluorescence also showed co-localization of SPR- with glutamic acid decarboxylase-immunoreactivity, but not with parvalbumin-immunoreactivity, in the striatal neurons. Taken together with previous reports, the present study has suggested that a sub-population of striatal GABA-ergic neurons, most possibly GABA-ergic interneurons, may also receive direct physiological modulation by tachykinins through SPR in the basal ganglia of mammals.