Overexpressing circ_0000831 is sufficient to inhibit neuroinflammation and vertigo in cerebral ischemia through a miR-16-5p-dependent mechanism

Circular RNAs (circRNAs) hold potential as stroke-related biomarkers due to involvement in various pathophysiological processes associated with cerebral ischemia and stability in peripheral blood. Differentially expressed circulating circRNAs were identified by preliminary sequencing analysis, through which we identified underexpressed circ_0000831 in ischemic stroke (IS). Validation was performed in peripheral blood of IS patients by quantitative polymerase chain reaction. Microglia was exposed to oxygen-glucose deprivation (OGD), where polarization phenotypes and inflammation were assessed. Middle cerebral artery occlusion was performed in mice to mimic ischemic stroke-induced vertigo, where cerebral blood flow, neurological deficits, vertigo degree, infarct area, inflammation and cell apoptosis were assayed in response to ectopic expression and knockdown of circ_0000831, miR-16-5p, and AdipoR2. Mechanically, circ_0000831 bound to miR-16-5p and downregulated miR-16-5p, and AdipoR2 was targeted by miR-16-5p and increased PPARγ expression in microglia. Furthermore, circ_0000831, AdipoR2, or PPARγ overexpression or miR-16-5p inhibition alleviated neuroinflammation, vertigo, neurological deficit, and cell apoptosis in MCAO mice. Consistently, circ_0000831, AdipoR2, or PPARγ upregulation or miR-16-5p downregulation diminished apoptosis and inflammation of OGD-induced microglia. Consequently, these findings pinpoint the circ_0000831/miR-16-5p/AdipoR2 axis as an essential signaling pathway during ischemia stroke. Thus, the circRNA circ_0000831 may work as a possible target for novel treatment in patients with ischemic stroke.

MicroRNAs Play a Role in Parkinson’s Disease by Regulating Microglia Function: From Pathogenetic Involvement to Therapeutic Potential

Parkinson’s disease (PD) is a clinically common neurodegenerative disease of the central nervous system (CNS) characterized by loss of dopamine neurons in the substantia nigra. Microglia (MG), as an innate immune cell in the CNS, are involved in a variety of immunity and inflammatory responses in the CNS. A number of studies have shown that the overactivation of MG is one of the critical pathophysiological mechanisms underlying PD. MicroRNAs (miRNAs) are considered to be an important class of gene expression regulators and are involved in a variety of physiological and pathological mechanisms, including immunity and inflammation. In addition, miRNAs can affect the progress of PD by regulating the expression of various MG genes and the polarization state of the MG. Here, we summarize recent articles and describe the important role of MG pathological polarization in the progression of PD, the diverse mechanisms responsible for how miRNAs regulate MG, and the potential therapeutic prospects of miRNAs for PD. We also propose that the regulation of miRNAs may be a novel protective approach against the pathogenesis of PD.

Efficacy and safety of tranexamic acid in orthopaedic trauma surgery: a meta-analysis

OBJECTIVE

To systematically review the efficacy and safety of tranexamic acid (TXA) in reducing blood transfusion and total blood loss in patients undergoing orthopaedic trauma surgery.

MATERIALS AND METHODS

A systematic literature search was performed using PubMed, Embase and Cochrane Library databases. The search time was incepted to February 2019. Two reviewers independently screened literature, extracted data, and assessed risk of bias. Then, meta-analysis was performed using RevMan 5.3.

RESULTS

A total of 10 studies were included, with 936 patients. The pooled results indicated that TXA group was superior to control group in the total blood loss [MD=-157.61, 95%CI (-250.09, -65.13), p=0.0008], blood transfusion [OR=0.59, 95%CI (0.43, 0.81), p=0.001], and the wound complications [OR=0.59, 95%CI (0.43, 0.81), p=0.001]. There was no significant difference in risk of thromboembolic events [OR=1.27, 95%CI (0.78, 2.12), p=0.35] and the mortality [OR=0.79, 95%CI (0.35, 1.78), p=0.57] between TXA and control group.

CONCLUSIONS

TXA could effectively reduce blood transfusion, total blood loss, and wound complications in patients undergoing orthopedic trauma surgery. Furthermore, TXA does not significantly increase the incidence of thromboembolic events and mortality. Due to the limited quality of the included studies, more high-quality works are required to verify the above conclusions.

MicroRNA-219a-5p-mediated inhibition of CaMKIIγ facilitates vestibular compensation in acute vertigo by promoting protein kinase C expression

Vestibular compensation (VC) refers to a behavioral recovery process in which firing rates of bilateral vestibular nuclei neurons are rebalanced. Our study aimed to investigate the underlying mechanism by which miR-219a-5p regulates Ca²⁺ /calmodulin-dependent protein kinase II γ isoform (CaMKIIγ) and protein kinase C (PKC) in VC. A unilateral vestibular deafferentation rat model was established by unilateral labyrinthectomy (UL), after which VC was evaluated in rats with UL-induced vertigo-like behavior by measuring vestibular defect behavior and performing rotarod tests, as well as by BrdU immunohistochemistry on medial vestibular nuclei. We found that miR-219a-5p was increased while CaMKIIγ was decreased during VC in the medial vestibular nucleus of rats that had undergone UL. Next, gain- and loss-of-function assays were conducted to evaluate the effects of miR-219a-5p and CaMKIIγ on the vestibular defect behaviors and VC, the results of which suggested that in rats after UL overexpression of CaMKIIγ inhibited VC, while overexpression of miR-219a-5p facilitated VC. A dual-luciferase reporter gene assay identified that miR-219a-5p targeted CaMKIIγ. This led to additional experiments showing that miR-219a-5p aptomir expression downregulated CaMKIIγ in cortical cells with a concomitant increase in PKC expression, which were verified further in vivo. In summary, in rats with acute vertigo, miR-219a-5p overexpression inhibits CaMKIIγ and elevates PKC, thereby facilitating VC. Our study offers possible targets for further evaluation as treatment of acute vertigo in humans.

MicroRNA-217-5p ameliorates endothelial cell apoptosis induced by ox-LDL by targeting CLIC4

BACKGROUND AND AIMS

Endothelial cell apoptosis plays an essential role in the pathogenesis of atherosclerosis. MicroRNAs and chloride intracellular channels (CLICs) have been verified to participate in the endothelial cell apoptosis process, however, the underlying molecular mechanisms are still unclear. The main aim of this study was to investigate the biological effects of microRNA-217-5p (miR-217-5p) and CLIC4 on endothelial cell apoptosis in atherosclerosis.

METHODS AND RESULTS

An atherosclerotic mouse model (n = 18) was constructed by feeding apolipo protein E knockout ApoE^(-/-) mice with high-fat diet for 12 weeks. An atherosclerotic cell model was established by treating human aortic endothelial cells with oxidized low-density lipoprotein (ox-LDL; 50 μg/mL) for 24 h. Quantitative real-time polymerase chain reaction and immunofluorescent staining confirmed the downregulation of miR-217-5p and upregulation of CLIC4 in atherosclerotic endothelial cells. Combined with western blot, flow cytometry assay and Hoechst staining, we demonstrated that miR-217-5p upregulation or CLIC4 knockdown regulated the apoptosis-related genes, ameliorated mitochondrial membrane permeability and therefore inhibited the apoptosis of aortic endothelial cells induced by ox-LDL. We further confirmed that miR-217-5p inhibited apoptosis of endothelial cells through targeting CLIC4 using luciferase report assay and rescue experiments.

CONCLUSION

We revealed for the first time that miR-217-5p inhibited apoptosis of endothelial cells in atherosclerosis and identified CLIC4 as a novel target of miR-217-5p. Our work provides a potential therapeutic approach for the treatment of atherosclerosis.

Mechanical thrombectomy with second-generation devices for acute cerebral middle artery M2 segment occlusion: A meta-analysis

BACKGROUND

The benefit of mechanical thrombectomy for an acute ischemic stroke involving M2 segment occlusion is not clear, especially when performed with second-generation thrombectomy devices.

METHOD

We reviewed the literature to investigate clinical outcomes and the rates of recanalization, symptomatic intracerebral hematoma, and mortality in mechanical thrombectomy performed using second-generation thrombectomy devices. We compared the outcomes between patients treated for M2 and M1 occlusions.

RESULTS

Seven studies involving 805 patients with M2 thrombectomy were included in this meta-analysis. The functional independence rate 90 days after thrombectomy (modified Rankin Scale 0-2) was 59.3% (OR 1.81, 95% CI 1.74-1.88). The recanalization rate (thrombolysis in cerebral infarction 0-2) was 84.16% (OR 2.32, 95% CI 2.08-2.29). The symptomatic intracerebral hematoma rate was 4.9% (OR 1.05, 95% CI 1.03-1.09). The mortality was 7.7% (OR 1.08, 95% CI 1.03-1.13). The outcomes were better in patients with M2 occlusion than in those with M1 occlusion. In a subgroup analysis, we found that among patients with hypertension, mechanical thrombectomy achieved better functional outcomes and recanalization in M2 occlusion than M1 occlusion.

CONCLUSION

Mechanical thrombectomy performed with second-generation thrombectomy devices for M2 occlusion can provide a good functional outcome as well as satisfying recanalization. Moreover, there was no significant difference in the symptomatic intracerebral hematoma and mortality rates, suggesting this procedure is as safe in M2 occlusion as in M1 occlusion.

[Efficiency Analysis of EX16+10Y Kit on Detection of the Uygur Population in Xinjiang Province]

OBJECTIVES

To analyse the efficiency of EX16+10Y kit on the forensic detection of the Uygur in Xinjiang province.

METHODS

The blood samples were extracted from 4 620 male individuals of Uygur in Xinjiang province, and amplified by EX16+10Y kit. The typing of amplification products was performed by 3130xl genetic analyzer.

RESULTS

The genotyping graphs of 15 autosomal STR loci and 10 Y-chromosomal STR loci from 4 620 male individuals of Uygur in Xinjiang province were acquired completely. The genotype distribution of 15 autosomal STR loci was consistent with Hardy-Weinberg equilibrium. The heterozygosity, polymorphism information content and discrimination power of STR loci were 0.637-0.838, 0.580-0.860 and 0.811-0.978, respectively. There were 766 haplotypes in 10 Y -chromosomal STR loci.

CONCLUSIONS

The test results of EX16+10Y kit is accurate and trustworthy, which can simultaneously be used for the individual identification and the screening of paternal pedigree in practical work.

Limb remote ischaemic postconditioning-induced elevation of fibulin-5 confers neuroprotection to rats with cerebral ischaemia/reperfusion injury: Activation of the AKT pathway

Limb remote ischaemic postconditioning (RIPostC) is an effective and well-acknowledged treatment for brain ischaemia injury. The present study aimed to evaluate the role of fibulin-5 in the neuroprotection of RIPostC against cerebral ischaemia/reperfusion (I/R) injury in rats. The middle cerebral artery occlusion (MCAO) model was established in rats and then RIPostC was carried out by three cycles of 10 minutes occlusion/10 minutes release of the bilateral femoral artery at the beginning of the reperfusion. To downregulate the fibulin-5 level, fibulin-5 siRNA was injected into the lateral ventricle 24 hours before MCAO. According to our present study, RIPostC attenuated cerebral I/R injury by decreasing infarct volume, improving neurobehavioral score and suppressing blood brain barrier (BBB) leakage. Moreover, the mRNA and protein levels of fibulin-5 were upregulated by RIPostC at 24 hours and 72 hours after reperfusion. Downregulation of fibulin-5 attenuated the neuroprotection of RIPostC. Finally, the result showed that fibulin-5 was upregulated by RIPostC via activation of the PI3K/AKT pathway. Taken together, these results provide evidence that upregulation of fibulin-5 is involved in the beneficial effect of RIPostC against cerebral I/R injury.

Progranulin and short-term outcome in patients with acute ischaemic stroke

BACKGROUND AND PURPOSE

Stroke is a leading cause of death and severe disability worldwide. Serum biomarkers play a critical role in the assessment of the severity and prognosis in stroke patients.

METHODS

In this prospective cohort study, the measurement of serum progranulin (PGRN) was conducted in 316 participants, including 216 patients with an identified diagnosis of acute ischaemic stroke and 100 normal control subjects. The primary end-point was defined as all-cause mortality for a short-term follow-up of 6 months. Adverse functional outcome (modified Rankin Scale score ≥3) was considered as the secondary end-point.

RESULTS

The median value of serum PGRN for patients with acute ischaemic stroke was 64.2 ng/ml (interquartile range 54.6-73.7), which was significantly higher than the control group [59.7 (54.4-64.4) ng/ml; P < 0.001]. Multivariable linear regression suggested that PGRN levels were significantly correlated with body mass index, alcohol consumption, fasting blood glucose, total cholesterol, National Institutes of Health Stroke Scale (NIHSS) score and high-density lipoprotein cholesterol. Serum PGRN concentrations were independently associated with increased risks of all-cause mortality and adverse functional outcome after adjustment for clinical variables. In Cox proportional hazards models, PGRN levels were associated with the risk of mortality (hazard ratio 1.090, 95% confidence interval 1.033-1.150, P = 0.002). The net reclassification improvement of the model with added PGRN was 0.1902 (P = 0.0234) after adjustment for the variables in the Cox regression model for predicting all-cause mortality, and the integrated discrimination improvement was 0.1052 (P < 0.001).

CONCLUSIONS

Serum PGRN levels independently predicted all-cause mortality and adverse functional outcome in the short term in stroke patients. The discriminative power was improved by PGRN on the basis of NIHSS score.

Association of Serum Chemerin Levels with Acute Ischemic Stroke and Carotid Artery Atherosclerosis in a Chinese Population

BACKGROUND

The aim of this study was to examine the association between serum level of chemerin with AIS and carotid artery atherosclerosis, and to investigate the level of chemerin as a potential novel cerebrovascular risk factor.

MATERIAL AND METHODS

We compared the serum chemerin levels and cerebrovascular parameters between 70 AIS patients and 70 non-AIS subjects in a Chinese population. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of serum chemerin. The state of carotid artery plaques in the AIS group was detected by color Doppler ultrasound. We used SPSS software for statistical analysis.

RESULTS

Compared with the non-AIS group, serum level of chemerin in the AIS group increased significantly (p<0.01). Multivariable logistic regression suggested that serum chemerin level, neutrophil count, and BMI were independent risk factors for AIS (p<0.05). Compared with the non-unstable plaque group, there were significant differences from the unstable plaque group in serum chemerin level (p<0.01). Multivariable logistic regression analysis revealed that the LDL-C, FIB, and serum chemerin levels were independent risk factors for carotid artery plaque instability (P<0.05). The levels of serum chemerin in the subjects with no carotid artery plaque were significantly lower than in those with carotid artery plaques of 2 and ≥3 (P=0.013; P=0.01).

CONCLUSIONS

The results of this study suggest that the serum chemerin level may be an independent risk factor for AIS and carotid artery plaque instability in Chinese populations.

Quantitative assessment of association between rs1801133 polymorphism and susceptibility to stroke

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to stroke. To assess the association between this polymorphism and stroke risk, we conducted a comprehensive meta-analysis based on 73 eligible studies. A total of 73 studies, including 10,225 cases and 13,800 controls identified between 1999 and 2012, were selected through researching the PubMed, MEDLINE, EMBASE, Cochrane Library, Web of Science, and Chinese Biomedical Chinese National Knowledge Infrastructure and Literature database databases. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of stroke risk was associated with the rs1801133 polymorphism in all genetic models (homozygote model: OR 1.296, 95% CI 1.109-1.514; dominant model: OR 1.179, 95% CI 1.058-1.315; recessive model: OR 1.209, 95% CI 1.063-1.375; allele comparison model: OR 1.154, 95% CI 1.061-1.256). In the stratified analyses, significantly increased stroke risks were indicated among Asians in all genetic models (homozygote model: OR 1.726, 95% CI 1.314-2.267; dominant model: OR 1.535, 95% CI 1.282-1.838; recessive model: OR 1.452, 95% CI 1.160-1.818; allele comparison model: OR 1.403, 95% CI 1.211-1.626).The present meta-analysis suggests that rs1801133 polymorphism contributes to the risk of stroke, of note, in Asian populations.

Differences in Growth, and Nitrogen Uptake and Storage Between Two Container-Grown Cultivars of Rhododendron

One-year-old liners of an evergreen rhododendron (Rhododendron L. ‘H-1 P.J.M’) and a deciduous azalea (Rhododendron L. ‘Cannon's Double’) were used to determine nitrogen (N) uptake, remobilization, and storage in relation to plant growth from May to September. Plants were grown in a substrate of equal parts (by vol) vermiculite, pumice, and sandy loam soil and received liquid fertilization with or without N. Rate of N uptake was correlated with the rate of plant growth and maximum uptake occurred during July [azalea, &gt;4 mg/day (1.4E – 04 oz/day)] and August [rhododendron, &gt;2 mg/day (7.1E – 05 oz/day)]. Compared to the rhododendron used in this study, the azalea cultivar grew faster and had a greater rate of N uptake and uptake efficiency (azalea, 12 to 33%; rhododendron, 8 to 16%). The old leaves of the rhododendron remobilized N for new growth. New azalea leaves exported approx. 40% of their N by September when the stems and roots were actively accumulating biomass. The roots, stems and new leaves of the rhododendrons were still accumulating biomass by September. Our results suggest that transplanted 1-year-old liners of rhododendron and azalea contained sufficient N reserves in both the plant and substrate to support initial plant growth and that increasing availability of N in the substrate during the period of rapid growth can significantly increase N uptake while improving vegetative growth and the N status of both rhododendron and azalea.

Expression of testis specific ankyrin repeat and SOCS box-containing 17 gene

Human ASB-17 (Ankyrin Repeat and SOCS Box-containing 17) is a recently identified gene belonging to the ASB family, isolated from testis cDNA library. Human ASB-17 is expressed exclusively in testis among 16 tissues, revealed by Northern blot. Mouse Asb-17 was shown to be expressed from the third week post birth to adult by semi-quantitative RT-PCR analysis. In situ hybridization on frozen sections demonstrated that Asb-17 is expressed in spermatogenic cells in adult mouse, but not in Leydig cell and epididymis in adult mouse. ASB-17 proteins are highly conserved in mammals including human, mouse, rat, Canis familiaris and Macaca fascicularis.

Selective presynaptic propagation of long-term potentiation in defined neural networks

Induction of long-term potentiation (LTP) of the synaptic connection between two hippocampal glutamatergic neurons in a neural network formed in cell culture resulted in a specific pattern of potentiation at other connections within the network. We found that potentiation propagated from the site of induction retrogradely to glutamatergic or GABAergic synapses received by the dendrites of the presynaptic neuron and laterally to those made by its axonal collaterals onto other glutamatergic cells. In contrast, synapses made by the same presynaptic neuron onto GABAergic cells were not affected, and there was no postsynaptic lateral or forward propagation to other synapses received or made by the postsynaptic neuron. In addition, there was no secondary propagation to synapses not directly associated with the presynaptic neuron. Both induction and propagation of LTP required correlated spiking of the postsynaptic cell as well as the activation of the NMDA subtype of glutamate receptors. Such selective propagation suggests the existence of a long-range cytoplasmic signaling within the presynaptic neuron, leading to a specific pattern of coordinated potentiation along excitatory pathways in a neural network.

[Germline LKB1 gene mutation screening in 4 Chinese Peutz-Jeghers syndrome pedigrees]

OBJECTIVE

To evaluate the frequency and nature of LKB1 gene germline mutations in 4 large Chinese Peutz-Jeghers syndrome pedigrees.

METHODS

Four Chinese Peutz-Jeghers syndrome pedigrees were investigated. Two patients and 1 normal adult from each pedigree were selected, and genomic DNA from peripheral blood was extracted. The 9 exons of LKB1 gene were amplified by PCR. The products were tested by SSCP and abnormally shifted bands were sequenced. If there was no positive finding in any pedigree, the entire exons were sequenced.

RESULTS

The same 842 C deletion of LKB1 gene frame-shift mutations was found in 2 pedigrees, which resulted in truncated protein. No exon variant was found in the left 2 pedigrees.

CONCLUSIONS

LKB1 gene germline mutation is an important molecular pathogen of Peutz-Jeghers syndrome. 842 C deletion is a possible mutation hotspot and might be a common-ancestor mutation characteristic of Chinese.

[The rapid effects of steroids on glycine uptake in neuroblastoma cell strain SK-N-SH cells]

In the present study, glycine uptake in SK-N-SH cells was determined with liquid scintillation technique, and the rapid effects of steroids on glycine uptake in SK-N-SH cells were investigated. The results were as follows. High-affinity glycine uptake in SK-N-SH cells was dependent on Na+ and Cl-. Corticosterone (CORT), progesterone (P) and dexamethasone (DEX) had rapid effects on the glycine uptake. Since estradiol (E2) and deoxycorticosterone (DOC) had no effects, it was suggested that the rapid effects of steroids were specific. The rapid effects of CORT were concentration-dependent in a range of 10(-9)-10(-6) mol/L. The rapid effects were not affected by the inhibitor of protein synthesis and persisted even when CORT was conjugated with bovine serum album, but attenuated when Ca2+ was absent in the external medium. The results suggest that the steroid effect on glycine uptake in SK-N-SH cells was nongenomicly mediated.

Distributed synaptic modification in neural networks induced by patterned stimulation

Activity-dependent changes in synaptic efficacy or connectivity are critical for the development, signal processing and learning and memory functions of the nervous system. Repetitive correlated spiking of pre- and postsynaptic neurons can induce a persistent increase or decrease in synaptic strength, depending on the timing of the pre- and postsynaptic excitation. Previous studies on such synaptic modifications have focused on synapses made by the stimulated neuron. Here we examine, in networks of cultured hippocampal neurons, whether and how localized stimulation can modify synapses that are remote from the stimulated neuron. We found that repetitive paired-pulse stimulation of a single neuron for brief periods induces persistent strengthening or weakening of specific polysynaptic pathways in a manner that depends on the interpulse interval. These changes can be accounted for by correlated pre- and postsynaptic excitation at distant synaptic sites, resulting from different transmission delays along separate pathways. Thus, through such a 'delay-line' mechanism, temporal information coded in the timing of individual spikes can be converted into and stored as spatially distributed patterns of persistent synaptic modifications in a neural network.

Triplex formation by oligonucleotides containing novel deoxycytidine derivatives

Homopurine sequences of duplex DNA are binding sites for triplex-forming oligodeoxyribopyrimidines. The interactions of synthetic duplex DNA targets with an oligodeoxyribopyrimidine containing N4-(6-amino-2-pyridinyl)deoxycytidine (1), a nucleoside designed to interact with a single C-G base pair interruption of the purine target tract, was studied by UV melting, circular dichroism spectroscopy and dimethylsulfate alkylation experiments. Nucleoside 1 supports stable triplex formation at pH 7.0 with formation of a 1-Y-Z triad, where Y-Z is a base pair in the homopurine tract of the target. Selective interaction was observed when Y-Z was C-G, although A-T and, to a lesser extent, T-A and G-C base pairs were also recognized. The circular dichroism spectra of the triplex having a 1-C-G triad were similar to those of a triplex having a C(+)-G-C triad, suggesting that the overall structures of the two triplexes are quite similar. Removal of the 6-amino group from 1 essentially eliminated triplex formation. Reaction of a triplex having the 1-C-G triad with dimethylsulfate resulted in a 50% reduction of methylation of the G residue of this triad. In contrast, the G of a similar triplex containing a U-C-G triad was not protected from methylation by dimethylsulfate. These results are consistent with a binding mode in which the 6-amino-2-pyridinyl group of 1 spans the major groove of the target duplex at the 1-C-G binding site and forms a hydrogen bond with the O6 of G. An additional stabilizing hydrogen bond could form between the N4 of the imino tautomer of 1 and the N4 amino group of C.

Triplex formation by a psoralen-conjugated oligodeoxyribonucleotide containing the base analog 8-oxo-adenine

Oligodeoxyribonucleotides containing thymidine and 8-oxo-2'-deoxyadenosine can form pyr.pur.pyr type triplexes with double-stranded DNA. Unlike triplexes whose third strands contain thymidine and deoxycytidine, the stability of these triplexes is independent of pH. We have prepared d-ps-TAAATAAATTTTTAT-L [I(A)], where A is 8-oxo-2'-deoxyadenosine, ps is 4'-hydroxymethyl-4,5',8- trimethylpsoralen and L is a 6-amino-2-(hydroxymethyl)hexyl linker. The oligomer is designed to interact with a homopurine sequence in the promoter region of the human gene coding for the 92 kDa form of collagenase type IV. Oligomer I(A) and oligomer I(C), which contains 2'-deoxycytidine in place of 8-oxo-2'-deoxycytidine, both form stable triplexes at pH 6.2, but only I(A) forms a stable triplex with a model duplex DNA target at pH 7.5, as determined by UV melting experiments. Triplex formation is stabilized by the presence of the psoralen group. Upon irradiation both I(A) and I(C) form photoadducts with the DNA target at pH 6.2, but only I(A) forms a photoadduct at pH 7.5. In these photoreactions oligomer I(A) appears to selectively form a photoadduct with a C in the purine-rich strand of the duplex target. Although a T residue is present in the pyrimidine-rich strand of the target at the duplex/triplex junction, essentially no adduct formation takes place with this strand, nor is interstrand cross-linking observed. The extent of photoadduct formation decreases with increasing temperature, behavior which is consistent with the UV melting curve of the triplex. A tetramethylrhodamine derivative of I(A) was prepared and found to cross-link less extensively than I(A) itself. Oligomer I(A) is completely resistant to hydrolysis when incubated for 24h in the presence of 10% fetal bovine serum at 37 degree C, although it is hydrolyzed by S1 nuclease. The properties of oligomer I(A) suggest that 8-oxo- containing oligomers may find utility as antigene oligonucleotide reagents.

Cell membrane resealing by a vesicular mechanism similar to neurotransmitter release

After injury to the cell membrane, rapid resealing of the membrane occurs with little loss of intracellular contents. This process has been studied by measurement of the rate of dye loss after membrane puncture in both the sea urchin embryo and 3T3 fibroblasts. Resealing of disrupted cell membranes requires external calcium that can be antagonized by magnesium. Block of multifunctional calcium/calmodulin kinase, which regulates exocytotic vesicle availability at synapses, and of kinesin, which is required for outward-directed transport of vesicles, inhibited membrane resealing. Resealing was also inhibited by botulinum neurotoxins B and A, suggesting that the two synaptosomal-associated proteins synaptobrevin and SNAP-25 also participate in resealing. This pattern of inhibition indicates that the calcium-dependent mechanisms for cell membrane resealing may involve vesicle delivery, docking, and fusion, similar to the exocytosis of neurotransmitters.

[Changes of angiotensin II contents in rat plasma, brain, cardiovascular system and adrenal during stress]

The changes of content of angiotensin II (A II) in plasma, anterior hypothalamus, medulla oblongata, myocardium, vasculature and adrenals during acute and chronic stress were studied in rats. Compulsive cold-water swimming and trauma by limb-breaking were used to set acute stress models while cold environment of 4-8 degrees C was used to set chronic stress model. The results showed that: (1) The A II levels in plasma were significantly increased in all three stress- model groups, reaching to 900%, 390% and 134% of the control in the swimming group, the limb-broken group and the cold environment group, respectively. It's clear that the level of angiotension II in the acute stress groups were much higher than those in the chronic stress group. (2) The A II levels of the rat brain, myocardium and blood vessel were also increased in the stress animals except the limb-broken group. Furthermore, the contents of angiotensin II of the chronic stress animals were significantly higher than those of the acute stress animals in the brain, myocardium and blood vessels, but not in the adrenals. (3) The adrenal A II content was significantly higher than that of the control in all stressed animals. (4) The plasma corticosterone was also significantly increased over the control level in both the acute and chronic stress groups. These results suggest that circulating angiotensin II and tissue angiotensin II may play a role during the development of acute and chronic stress, respectively.

Heterokaryon myotubes with normal mouse and Duchenne nuclei exhibit sarcolemmal dystrophin staining and efficient intracellular free calcium control

Duchenne and mdx muscle tissues lack dystrophin where it normally interacts with glycoproteins in the sarcolemma. Intracellular free calcium ([Ca2+]i) is elevated in Duchenne and mdx myotubes and is correlated with abnormally active calcium-specific leak channels in dystrophic myotubes. We fused Duchenne human and normal mouse myoblasts and identified heterokaryon myotubes by Hoechst 33342 staining to measure the degree to which dystrophin introduced by normal nuclei could incorporate throughout the myotube at the sarcolemma and restore normal calcium homeostasis. Dystrophin expression in myotubes was determined by immunofluorescence and confocal laser scanning microscopy. Dystrophin was expressed at the sarcolemma in normal mouse and heterokaryon myotubes, but not in Duchenne myotubes. In heterokaryons, extensive dystrophin localization occurred at the sarcolemma even where only Duchenne nuclei were present, indicating that dystrophin does not exhibit nuclear domains. Heterokaryon, normal mouse and Duchenne myotube [Ca2+]i was measured using fura-2 and fluorescence ratio imaging. Heterokaryon and normal mouse myotubes were found to maintain similar levels of [Ca2+]i. In contrast, Duchenne myotubes had significantly higher [Ca2+]i (p < 0.001). Furthermore, the ability of heterokaryons to maintain normal [Ca2+]i did not depend on greater numbers of normal nuclei than Duchenne being present in the myotube. These results support the view that dystrophin expression in heterokaryons allows for efficient control of [Ca2+]i.

Changes in circulating and tissue angiotensin II during acute and chronic stress

Changes of angiotensin II and cAMP in plasma, brain tissue, adrenal gland and cardiovascular tissue during the acute and chronic stress were studied in rats. The acute stress group was subjected to compulsive cold water swimming for 20 min, while the chronic stress group was exposed to an ambient temperature of 4-8 degrees C for 5 days. The results indicated that plasma angiotensin II levels were significantly increased in both stress groups, reaching up to 900% and 134% of the control in the acute and chronic groups, respectively. Angiotensin II contents in the anterior hypothalamus, medulla oblongata, myocardium, vasculature and adrenals were also elevated in both groups. With the exception of the adrenals, the contents of tissue angiotensin II in the chronic stress animals were significantly higher than those of the acute stress animals. In contrast, cAMP levels in plasma and tissue (hypothalamus and adrenals) and corticosterone levels in plasma in the acute stress group were all higher than those in the chronic stress animals, although the levels of the latter group were also increased compared with the control group. These results suggest that circulating and tissue angiotensin II may play an important role in the acute and chronic stress responses and that angiotensin II should be classified as a stress hormone.

[Morphine decreased the content of cyclic AMP in the rat spinal cord]

It has been reported that morphine or opiate-like substances (OLS) can affect the contents of cyclic AMP and/or cyclic GMP in mammalian brain, but very little is known whether similar effects also occur in spinal cord. Using RIA method, we showed that morphine significantly decreased the content of cyclic AMP in the rat spinal cord in vivo and in vitro and this effect could be completely blocked by naloxone, while the concentration of cyclic GMP in rat spinal cord is unchanged. In view of the present experiment it is suggested that the changes of cyclic AMP in the central nervous system may be partly mediated by the action of morphine.