Overexpressed TGF-β in subchondral bone leads to mandibular condyle degradation

Emerging evidence has implied that subchondral bone plays an important role during osteoarthritis (OA) pathology. This study was undertaken to investigate whether abnormalities of the condylar subchondral bone lead to temporomandibular joint (TMJ) OA. We used an osteoblast-specific mutant TGF-β1 transgenic mouse, the CED mouse, in which high levels of active TGF-β1 occur in bone marrow, leading to abnormal bone remodeling. Subchondral bone changes in the mandibular condyles were investigated by micro-CT, and alterations in TMJ condyles were confirmed by histopathological and immunohistochemical analysis. Abnormalities in the condylar subchondral bone, characterized as fluctuant bone mineral density and microstructure and increased but uncoupled activity of osteoclasts and osteoblasts, were apparent in the 1- and 4-month CED mouse groups, while obvious cartilage degradation, in the form of cell-free regions and proteoglycan loss, was observed in the 4-month CED group. In addition, increased numbers of apoptotic chondrocytes and MMP9- and VEGF-positive chondrocytes were observed in the condylar cartilage in the 4-month CED group, but not in the 1-month CED group, compared with their respective age-matched controls. This study demonstrated that progressive degradation of mandibular condylar cartilage could be induced by the abnormal remodeling of the underlying subchondral bone during TMJOA progression.

Effect of bilateral deep brain stimulation of the subthalamic nucleus on freezing of gait in Parkinson's disease

OBJECTIVE

A prospective cohort study to evaluate the efficacy of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on freezing of gait (FOG) in patients with advanced Parkinson's disease.

METHODS

Patients (n = 10) with advanced Parkinson's disease were surgically implanted with microelectrodes to facilitate STN-DBS. Evaluations of FOG, motor function, activities of daily living and neuropsychological function were carried out in on-medication and off-medication states (with and without levodopa treatment), before surgery and at 6 and 12 months postoperatively.

RESULTS

STN-DBS was associated with significant improvement in FOG score and neuropsychological function at both 6 and 12 months postoperatively, compared with preoperatively. Significant postoperative improvements were also observed in motor function and activities of daily living. Daily levodopa dosage was significantly lower at both 6 and 12 months postoperatively.

CONCLUSIONS

STN-DBS improved FOG in patients with advanced Parkinson's disease. The significant reduction in levodopa dosage and improvement in neuropsychological function may be the reason for the therapeutic effect seen with STN-DBS.

Hypoxic preconditioning attenuates global cerebral ischemic injury following asphyxial cardiac arrest through regulation of delta opioid receptor system

This study was designed to investigate whether delta opioid receptor (DOR) is involved in the neuroprotective effect induced by hypoxic preconditioning (HPC) in the asphyxial cardiac arrest (CA) rat model. Twenty-four hours after the end of 7-day HPC, the rats were subjected to 8-min asphyxiation and resuscitated with a standardized method. In the asphyxial CA rat model, HPC improved the neurological deficit score (NDS), inhibited neuronal apoptosis, and increased the number of viable hippocampal CA1 neurons at 24 h, 72 h, or 7 days after restoration of spontaneous circulation (ROSC); however, the above-mentioned neuroprotection of HPC was attenuated by naltrindole (a selective DOR antagonist). The expression of hypoxia-inducible factor-1α (HIF-1α) and DOR, and the content of leucine enkephalin (L-ENK) in the brain were also investigated after the end of 7-day HPC. HPC upregulated the neuronal expression of HIF-1α and DOR, and synchronously elevated the content of L-ENK in the rat brain. HIF-1α siRNA was used to further elucidate the relationship between HIF-1α and DOR in the HPC-treated brain. Knockdown of HIF-1α by siRNA markedly abrogated the HPC induced upregulation of HIF-1α and DOR. The present study demonstrates that the expression of DOR in the rat brain is upregulated by HIF-1α following exposure to 7-day HPC, at the same time, HPC also increases the production of endogenous DOR ligand L-ENK in the brain. DOR activation after HPC results in prolonged neuroprotection against subsequent global cerebral ischemic injury, suggesting a new mechanism of HPC-induced neuroprotection on global cerebral ischemia following CA and resuscitation.

RU486 (mifepristone) ameliorates cognitive dysfunction and reverses the down-regulation of astrocytic N-myc downstream-regulated gene 2 in streptozotocin-induced type-1 diabetic rats

Diabetic cognitive dysfunction (DCD), usually accompanied with chronically elevated glucocorticoids and hippocampal astrocytic alterations, is one of the most serious complications in patients with type-1 diabetes. However, the role for chronically elevated glucocorticoids and hippocampal astrocytic activations in DCD remains to be elucidated, and it is not clear whether astrocytic N-myc downstream-regulated gene 2 (NDRG2, involved in cell differentiation and development) participated in DCD. In the present study, three months after streptozotocin (STZ)-induced type-1 diabetes onset, rats showed cognitive impairments in Morris water maze test as well as elevated corticosterone level. Diabetic rats also presented down-regulation of glial fibrillary acidic protein (GFAP, a key indicator of astrocytic reactivity) and NDRG2 in hippocampus revealed by immunohistochemistry staining, real-time PCR and Western blot. Moreover, the diabetic cognitive impairments were ameliorated by 9-day glucocorticoids receptor (GR) blockade with RU486, and the down-regulation of hippocampal NDRG2 and GFAP in diabetic animals was also attenuated by 9-day GR blockade. These results suggest that glucocorticoids-GR system is crucial for DCD, and that astrocytic reactivity and NDRG2 are involved in these processes. Thus, inhibiting GR activation in the hippocampus may be a novel therapeutic strategy for treating DCD.

Ferrous chelator 2,2'-dipyridyl attenuates cerebral vasospasm after experimental subarachnoid haemorrhage in rabbits

The effect of 2,2'-dipyridyl (DP) on cerebral vasospasm was investigated in a double-injection rabbit model of subarachnoid haemorrhage (SAH). Thirty-six animals were divided between four groups: control (sham-operated), SAH (model alone), SAH + DP (the SAH model in which DP dissolved in dimethyl sulphoxide [DMSO] was injected once daily for 5 days into the cisterna magna), and SAH + DMSO (the SAH model in which DMSO [vehicle] was injected daily for 5 days). There were significant differences in the basilar artery luminal area, wall thickness, neurological deficit score and vasospasm index between the SAH + DP and SAH groups. There was a significant negative correlation between arterial luminal area and arterial wall thickness, and also between the neurological deficit score and vasospasm index. Cells that were positive for terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL) and p53 expression were significantly increased in the SAH + DMSO and SAH groups, but not in the SAH + DP group, versus controls. Thus, DP may attenuate cerebral vasospasm after SAH by suppressing p53-induced apoptosis in the cerebral vessels.

Neuroprotective Effect of Gypenosides against Oxidative Injury in the Substantia Nigra of a Mouse Model of Parkinson's Disease

Oxidative injury has been implicated in the aetiology of Parkinson's disease (PD) and gypenosides (GP), which are saponins with various bioactivities, have shown antioxidative effects in vitro. The present study was designed to evaluate the effect of GP on a 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP)-induced mouse model of PD. Acute administration of MPTP led to decreased glutathione content and reduced superoxide dismutase activity in the substantia nigra of the mice, which resulted in oxidative

stress, loss of nigral dopaminergic neurons and motor dysfunction. Co-treatment with GP attenuated all the injuries induced by MPTP in a dose-dependent manner. The neuroprotective effect of GP may be attributed to increased antioxidation, as manifested by significantly increased glutathione content and enhanced superoxide dismutase activity in the substantia nigra. These results strongly indicate the possible therapeutic potential of GP as an antioxidant in PD.

A simplified paraffin embedding method for small botanical samples

We present a simplified paraffin embedding method suitable for unsuberized or unlignified small botanical samples (diameter < 0.3 cm). Only 2 h are required to yield plant tissues embedded in paraffin for anatomical observation and molecular analysis. Our method achieved morphological preservation of cell structures and conservation of nucleic acids that were equivalent to the traditional protocol. Fourier transform infrared spectrometry showed that the degree of degradation of the cytoplasmic components (e.g., protein) resulting from our simplified protocol was similar to that of the traditional protocol. The DNA samples embedded using the simplified method was extractable and could be used for PCR analysis. The DNA quality was equivalent to that embedded using the traditional method.

Morphological brain changes associated with Schneider's first-rank symptoms in schizophrenia: a MRI study

BACKGROUND

Schneider's first-rank symptoms involve an alienated feature of the sense of one's own mental or physical activity. To clarify the brain morphological basis for the production of these symptoms, volumes of the frontal and medial temporal regions and their clinical correlates were examined in patients with schizophrenia.

METHOD

Twenty-two patients with schizophrenia and 44 age- and gender-matched healthy control subjects were included. All patients were in their psychotic episodes with definite Schneiderian symptoms, rated by using the Scale for Assessment of Positive Symptoms. Volumetric measurements of high-resolution magnetic resonance imaging were performed in the prefrontal area, cingulate gyrus, and precentral gyrus, and the medial temporal structures such as the amygdala, hippocampus, and parahippocampal gyrus.

RESULTS

Patients had significantly decreased volumes in the cingulate gray matter and the amygdala compared to controls. In the patient group, Schneiderian symptom severity showed significant inverse correlations with volumes of the right posterior cingulate gray matter and of the left anterior parahippocampal gyrus.

CONCLUSIONS

Schneiderian symptoms may be associated with morphological abnormalities in the limbic-paralimbic regions such as the cingulate gyrus and parahippocampal gyrus, which possibly serve the self-monitoring function and the coherent storage and reactivation of information.

Heterologous expression of the single-mutation glucose isomerase (GIG138P) gene in Streptomyces lividans and its genetic instability

A 1.3-kb PstI-BamHI fragment containing the single-mutation glucose isomerase (GIG138P, GI1) gene and its natural promoter was inserted into PstI-BglII linearized Streptomyces vector pIJ702. The ligation mixture was then introduced into Streptomyces lividans TK54 protoplasts; transformants were identified based on their thiostrepton resistance (ThR) and insertional inactivation of the melanin phenotype; and three white colonies, XY-2, 6, and 9, harboring recombinant expression plasmid pYH703, were obtained. Enzyme assay and SDS-PAGE analysis indicated that the GI1 gene was expressed, the intracellular GI1 specific activity was 6 U/mg, and GI1 accounted for 20% of the soluble proteins in S. lividans. Restriction analysis and Southern blot of pYH703 showed the existence of plasmid deletion, presumably owing to the interaction between the mel and GI1 sequences. Continuous liquid cultures of the recombinant strain demonstrated that the GI1 specific activity and GI1 expression in S. lividans decreased, and more obviously under non-selective conditions.

Mechanism-based discovery of ligands that counteract inhibition of the nicotinic acetylcholine receptor by cocaine and MK-801

Nicotinic acetylcholine receptors (AChR) belong to a family of proteins that form ligand-gated transmembrane ion channels. They are involved in the fast transmission of signals between cells and the control of intercellular communication in the nervous system. A variety of therapeutic agents and abused drugs, including cocaine, inhibit the AChR and monoamine transporters and interfere with nervous system function. Here we describe a mechanism-based approach to prevent this inhibition. We had previously developed presteady-state kinetic (transient kinetic) techniques, with microsecond-to-millisecond time resolutions, for investigations of reactions on cell surfaces that allow one to determine the effects of inhibitors not only on the channel-opening probability but also on the opening and closing rates of the AChR channel. The transient kinetic measurements led to two predictions. (i) Ligands that bind to a regulatory site on the closed-channel conformation of the AChR with higher affinity than to the site on the open-channel form shift the equilibrium toward the closed-channel form, thereby inhibiting the receptor. (ii) Ligands that bind to a regulatory site with an affinity for the open conformation equal to or higher than their affinity for the closed conformations are expected not to inhibit the receptor and to displace inhibitors. The identification of such ligands in a combinatorial library of RNA ligands is reported. The implication of this approach to other protein-mediated reactions in which an inhibitor changes the equilibrium between active and inactive conformations is discussed.

Deletion of the Escherichia coli pseudouridine synthase gene truB blocks formation of pseudouridine 55 in tRNA in vivo, does not affect exponential growth, but confers a strong selective disadvantage in competition with wild-type cells

Previous work from this laboratory (Nurse et al., RNA, 1995, 1:102-112) established that TruB, a pseudouridine (psi) synthase from Escherichia coli, was able to make psi55 in tRNA transcripts but not in transcripts of full-length or fragmented 16S or 23S ribosomal RNAs. By deletion of the truB gene, we now show that TruB is the only protein in E. coli able to make psi55 in vivo. Lack of TruB and psi55 did not affect the exponential growth rate but did confer a strong selective disadvantage on the mutant when it was competed against wild-type. The negative selection did not appear to be acting at either the exponential or stationary phase. Transformation with a plasmid vector conferring carbenicillin resistance and growth in carbenicillin markedly increased the selective disadvantage, as did growth at 42 degrees C, and both together were approximately additive such that three cycles of competitive growth sufficed to reduce the mutant strain to approximately 0.2% of its original value. The most striking finding was that all growth effects could be reversed by transformation with a plasmid carrying a truB gene coding for a D48C mutation in TruB. Direct analysis showed that this mutant did not make psi55 under the conditions of the competition experiment. Therefore, the growth defect due to the lack of TruB must be due to the lack of some other function of the protein, possibly an RNA chaperone activity, but not to the absence of psi55.

Growth regulation of human variant histone genes and acetylation of the encoded proteins

The family of human histone genes consists of replication-dependent and independent subtypes. The replication-independent histone genes, also known as variants, give rise to distinct mRNAs, whose expression is regulated depending on the growth state of the cell, tissue type and developmental stage. In turn, the histone variants are differentially synthesized and modified by acetylation. Consequently, chromatin structure is altered resulting in complex changes in gene expression. The high conservation among histone protein subtypes suggests that they are indispensable. In addition, conservation of the positions of acetylation within subtypes suggests that the location of these sites is functionally important for the eukaryotic cell. For example, the structures of transcriptionally active and repressed chromatin are different depending on the acetylation state of histone proteins [1-3]. In addition, transcriptionally active and repressed chromatin contains distinct histone variants [4]. Specialized histone variants are targeted to the centromere of the chromosome, where they are essential for chromosome segregation [5]. Other specialized histones exist that are essential for development [6]. Changes in histone acetylation have been implicated in the down-regulation of a tumour suppressor gene in human breast cancer [7]. Acetylation also plays an important role in X chromosome inactivation as well as hormone-mediated transcriptional regulation [8, 9]. We propose here a novel model for histone variant gene regulation at the post-transcriptional level, which provides the groundwork to define the pathways regulating the synthesis of these variants.

High-affinity binding to the GM-CSF receptor requires intact N-glycosylation sites in the extracellular domain of the beta subunit

The human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor consists of 2 glycoprotein subunits, GMRalpha and GMRbeta. GMRalpha in isolation binds to GM-CSF with low affinity. GMRbeta does not bind GM-CSF by itself, but forms a high-affinity receptor in association with GMRalpha. Previously, it was found that N-glycosylation of GMRalpha is essential for ligand binding. The present study investigated the role of N-glycosylation of the beta subunit on GM-CSF receptor function. GMRbeta has 3 potential N-glycosylation sites in the extracellular domain at Asn58, Asn191, and Asn346. Single mutants and triple mutants were constructed, converting asparagine in the target sites to aspartic acid or alanine. A single mutation at any of the 3 consensus N-glycosylation sites abolished high-affinity GM-CSF binding in transfected COS cells. Immunofluorescence and subcellular fractionation studies demonstrated that all of the GMRbeta mutants were faithfully expressed on the cell surface. Reduction of apparent molecular weight of the triple mutant proteins was consistent with loss of N-glycosylation. Intact N-glycosylation sites of GMRbeta in the extracellular domain are not required for cell surface targeting but are essential for high-affinity GM-CSF binding.

[Effect of unsymmetrical cutting along both river slopes on rainstorm-runoff process]

A simulation experiment was conducted to compare the effect of cutting and no-cutting at both slopes along a river on the rainstorm run-off in catchment, and a model was constructed. The results showed that the appearance of outflow and peak flow of surface run-off was later on forest slope than on forest-cutting slope. On forest slope, the duration was prolonged, and the peak flow and surface runoff were lower. These effects were more obvious as the slope gradient was bigger. When rain intensity was 1.98 mm.min-1 and rainfall was 108.8 mm, the peak flow and the total runoff on both forested slopes of gradient 15 degrees was 5% and 4% less than that on the cutting slopes, respectively.