Integrating TSPO PET imaging and transcriptomics to unveil the role of neuroinflammation and amyloid-β deposition in Alzheimer's disease

PURPOSE

Despite the revealed role of immunological dysfunctions in the development and progression of Alzheimer's disease (AD) through animal and postmortem investigations, direct evidence regarding the impact of genetic factors on microglia response and amyloid-β (Aβ) deposition in AD individuals is lacking. This study aims to elucidate this mechanism by integrating transcriptomics and TSPO, Aβ PET imaging in clinical AD cohort.

METHODS

We analyzed 85 patients with PET/MR imaging for microglial activation (TSPO, [18F]DPA-714) and Aβ ([18F]AV-45) within the prospective Alzheimer's Disease Immunization and Microbiota Initiative Study Cohort (ADIMIC). Immune-related differentially expressed genes (IREDGs), identified based on AlzData, were screened and verified using blood samples from ADIMIC. Correlation and mediation analyses were applied to investigate the relationships between immune-related genes expression, TSPO and Aβ PET imaging.

RESULTS

TSPO uptake increased significantly both in aMCI (P < 0.05) and AD participants (P < 0.01) and showed a positive correlation with Aβ deposition (r = 0.42, P < 0.001). Decreased expression of TGFBR3, FABP3, CXCR4 and CD200 was observed in AD group. CD200 expression was significantly negatively associated with TSPO PET uptake (r =-0.33, P = 0.013). Mediation analysis indicated that CD200 acted as a significant mediator between TSPO uptake and Aβ deposition (total effect B = 1.92, P = 0.004) and MMSE score (total effect B =-54.01, P = 0.003).

CONCLUSION

By integrating transcriptomics and TSPO PET imaging in the same clinical AD cohort, this study revealed CD200 played an important role in regulating neuroinflammation, Aβ deposition and cognitive dysfunction.

ABCA7-Associated Clinical Features and Molecular Mechanisms in Alzheimer's Disease

Alzheimer's disease (AD) is the most common type of neurodegenerative disease and its pathogenesis is still unclear. Genetic factors are thought to account for a large proportion of the overall AD phenotypes. ATP-binding cassette transporter A7 (ABCA7) is one of the most important risk gene for AD. Multiple forms of ABCA7 variants significantly increase the risk of AD, such as single-nucleotide polymorphisms, premature termination codon variants, missense variants, variable number tandem repeat, mutations, and alternative splicing. AD patients with ABCA7 variants usually exhibit typical clinical and pathological features of traditional AD with a wide age of onset range. ABCA7 variants can alter ABCA7 protein expression levels and protein structure to affect protein functions such as abnormal lipid metabolism, amyloid precursor protein (APP) processing, and immune cell function. Specifically, ABCA7 deficiency can cause neuronal apoptosis by inducing endoplasmic reticulum stress through the PERK/eIF2α pathway. Second, ABCA7 deficiency can increase Aβ production by upregulating the SREBP2/BACE1 pathway and promoting APP endocytosis. In addition, the ability of microglia to phagocytose and degrade Aβ is destroyed by ABCA7 deficiency, leading to reduced clearance of Aβ. Finally, disturbance of lipid metabolism may also be an important method by which ABCA7 variants influence the incidence rate of AD. In the future, more attention should be given to different ABCA7 variants and ABCA7 targeted therapies for AD.

Injection of amyloid-β to lateral ventricle induces gut microbiota dysbiosis in association with inhibition of cholinergic anti-inflammatory pathways in Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is the most common neurodegenerative disease and its pathogenesis is still unclear. There is dysbiosis of gut microbiota in AD patients. More importantly, dysbiosis of the gut microbiota has been observed not only in AD patients, but also in patients with mild cognitive impairment (MCI). However, the mechanism of gut microbiota dysbiosis in AD is poorly understood. Cholinergic anti-inflammatory pathway is an important pathway for the central nervous system (CNS) regulation of peripheral immune homeostasis, especially in the gut. Therefore, we speculated that dysfunction of cholinergic anti-inflammatory pathway is a potential pathway for dysbiosis of the gut microbiota in AD.

METHODS

In this study, we constructed AD model mice by injecting Aβ_1-42 into the lateral ventricle, and detected the cognitive level of mice by the Morris water maze test. In addition, 16S rDNA high-throughput analysis was used to detect the gut microbiota abundance of each group at baseline, 2 weeks and 4 weeks after surgery. Furthermore, immunofluorescence and western blot were used to detect alteration of intestinal structure of mice, cholinergic anti-inflammatory pathway, and APP process of brain and colon in each group.

RESULTS

Aβ_1-42 i.c.v induced cognitive impairment and neuron damage in the brain of  mice. At the same time, Aβ_1-42 i.c.v induced alteration of gut microbiota at 4 weeks after surgery, while there was no difference at the baseline and 2 weeks after surgery. In addition, changes in colon structure and increased levels of pro-inflammatory factors were detected in Aβ_1-42 treatment group, accompanied by inhibition of cholinergic anti-inflammatory pathways. Amyloidogenic pathways in both the brain and colon were accelerated in Aβ_1-42 treatment group.

CONCLUSIONS

The present findings suggested that Aβ in the CNS can induce gut microbiota dysbiosis, alter intestinal structure and accelerate the amyloidogenic pathways, which were related to inhibiting cholinergic anti-inflammatory pathways.

Identification of potential predictive biomarkers and biological pathways and the correction with immune infiltration in the activation of Crohn's disease

Crohn's disease (CD), a subtype of inflammatory bowel disease (IBD), has increasing prevalence in the world. Due to the lack of cure strategy, most patients with CD develop progressive disease companying with a series of serious complications. Therefore, exploring molecular mechanism differences between active and inactive CD will help in the screening of predict markers and therapeutic targets. In this study, we analyzed differentially expressed genes (DEGs) and molecular pathways through between active and inactive CD patients. In addition, the abundance of 22 immune cell types were assessed by using the CIBERSORT. The hub DEGs were screened out by the CytoHubba in Cytoscape, followed by the least absolute shrinkage and selection operator (LASSO) regression. Finally, the clinical predictive model was constructed by binary logistic regression model. The diagnostic efficacy was tested by receiver operating characteristic (ROC) curve and verified in independent datasets. The results showed that there were 137 DEGs between the active and inactive CD. Most of them were involved in regulating the immunity process. In addition, the decreased abundance of CD8 T cells and the increased abundance of M0, M1 macrophages, and neutrophils were closely related to CD activation. CXCL9, C3AR1, IL1B, and TLR4 were the hub gene and can be applied to the prediction of CD activation. Our results provided important targets for the prediction of CD activation and the selection of therapeutic targets.

TMEM151A Variants Cause Paroxysmal Kinesigenic Dyskinesia: A Large-Sample Study

BACKGROUND

Paroxysmal kinesigenic dyskinesia (PKD) is the most common type of paroxysmal dyskinesias. Only one-third of PKD patients are attributed to proline-rich transmembrane protein 2 (PRRT2) mutations.

OBJECTIVE

We aimed to explore the potential causative gene for PKD.

METHODS

A cohort of 196 PRRT2-negative PKD probands were enrolled for whole-exome sequencing (WES). Gene Ranking, Identification and Prediction Tool, a method of case-control analysis, was applied to identify the candidate genes. Another 325 PRRT2-negative PKD probands were subsequently screened with Sanger sequencing.

RESULTS

Transmembrane Protein 151 (TMEM151A) variants were mainly clustered in PKD patients compared with the control groups. 24 heterozygous variants were detected in 25 of 521 probands (frequency = 4.80%), including 18 missense and 6 nonsense mutations. In 29 patients with TMEM151A variants, the ratio of male to female was 2.63:1 and the mean age of onset was 12.93 ± 3.15 years. Compared with PRRT2 mutation carriers, TMEM151A-related PKD were more common in sporadic PKD patients with pure phenotype. There was no significant difference in types of attack and treatment outcome between TMEM151A-positive and PRRT2-positive groups.

CONCLUSIONS

We consolidated mutations in TMEM151A causing PKD with the aid of case-control analysis of a large-scale WES data, which broadens the genotypic spectrum of PKD. TMEM151A-related PKD were more common in sporadic cases and tended to present as pure phenotype with a late onset. Extensive functional studies are needed to enhance our understanding of the pathogenesis of TMEM151A-related PKD. © 2021 International Parkinson and Movement Disorder Society.

Inflammatory pathways in Alzheimer's disease mediated by gut microbiota

In the past decade, numerous studies have demonstrated the close relationship between gut microbiota and the occurrence and development of Alzheimer's disease (AD). However, the specific mechanism is still unclear. Both the neuroinflammation and systemic inflammation serve as the key hubs to accelerate the process of AD by promoting pathology and damaging neuron. What's more, the gut microbiota is also crucial for the regulation of inflammation. Therefore, this review focused on the role of gut microbiota in AD through inflammatory pathways. Firstly, this review summarized the relationship and interaction among gut microbiota, inflammation, and AD. Secondly, the direct and indirect regulatory effects of gut microbiota on AD through inflammatory pathways were described. These effects were mainly mediated by the component of the gut microbiota (lipopolysaccharides (LPS) and amyloid peptides), the metabolites of bacteria (short-chain fatty acids, branched amino acids, and neurotransmitters) and functional by-products (bile acids). In addition, potential treatments (fecal microbiota transplantation, antibiotics, probiotics, prebiotics, and dietary interventions) for AD were also discussed through these mechanisms. Finally, according to the current research status, the key problems to be solved in the future studies were proposed.

Immunomodulatory effects of IL-33 and IL-25 in an ovalbumin-induced allergic rhinitis mouse model

Both interleukin (IL)-33 and IL-25 induce Th2-type cytokine production by various cell types, suggesting that they may contribute to development of allergic disorders, however, the immunomodulatory effects of IL-33 and IL-25 in ovalbumin (OVA)-induced allergic rhinitis (AR) remain unclear. In the present study, anti-IL-33 and anti-IL-25 Abs were administrated intranasally during rechallenge in OVA-induced AR. Immunomodulatory effects were evaluated by measuring nasal rubbing, sneezing occurrence, serum OVA-specific antibodies, Th2 immune responses, neutrophil, eosinophil and mast cell recruitment into the nasal mucosa. We found that treatment with anti-IL-33 Ab markedly reduced nasal rubbing, sneezing events, Th2 immune responses, serum OVA-specific IgE and IgG1 levels, mucosal neutrophil, eosinophil and mast cell infiltration. In contrast, the effect of IL-25 antagonism was limited to attenuating the Th2 immune responses, and neutrophil and eosinophil infiltration. These observations indicate that IL-33 and IL-25 play a pathogenic role in an established AR mouse model, with a greater contribution of IL-33 than IL-25. Our findings suggest that IL-33 neutralization may be a potential approach for treatment of AR.

[Analysis on prediction power of HIV infection risk assessment tool in men who have sex with men in Guizhou province]

Objective: To evaluate the prediction power of HIV infection risk assessment tool and the applicability in MSM in Guizhou province. Methods: MSM were recruited through snowball sampling method. Questionnaire surveys were conducted among the MSM using HIV infection risk assessment tool, and combined with HIV serologic test results, the risk prediction power of HIV infection risk assessment tool was evaluated. Results: A total of 3 379 MSM were recruited from January 2018 to December 2019 in Guizhou. The HIV infection rate was 3.3%(111/3 379). The mean risk scores of HIV positive and HIV negative MSM were (12.15±3.08) and (12.07±3.07), respectively. The difference in risk score was significant between MSM with different HIV status (t=8.69, P<0.001). According to the principle of decision tree, individual risk scores were divided into following three categories: ≤11.96, 11.97-14.80 and >14.80, the HIV infection rate was 0.8%, 4.3% and 8.6% respectively, suggesting that the higher the individual risk score was, the higher the HIV infection rate was (trend χ²=88.18, P<0.001). Multivariate logistic regression analysis showed that the higher the individual risk score was, the higher the risk of HIV infection was. Compared to the total score ≤11.96, the aOR values at total scores of 11.97-14.80 and >14.80 were 6.34 (95%CI: 3.38-11.88) and 14.07(95%CI: 7.44-26.61), respectively. The risk of HIV infection in Miao ethnic group was higher than that in Han ethnic group (aOR=1.83, 95%CI:1.04-3.21), and the risk of HIV infection in those with education level of primary school and below was higher than that in undergraduates or those with education level of junior college and above (aOR=2.50, 95%CI:1.06-5.88), and the risk of HIV infection was higher in those who had bisexual behaviors than in those who had homosexual behaviors (aOR=1.95, 95%CI:1.19-3.19). The risk of HIV infection was higher in those who had never received HIV testing (aOR=1.53, 95%CI:1.01-2.33). The area under the receiver operating characteristic (ROC) curve and area under ROC (AUC) for HIV infection prediction was 0.751 (95%CI:0.710-0.792, P<0.001). The maximum Youden's index was individual risk score of 12.56, and the sensitivity of the risk assessment tool was 0.838, and its specificity was 0.412. Conclusions: The results of HIV infection risk assessment tool in Guizhou indicated that in MSM the higher the individual risk score, the higher the risk of HIV infection is. The tool can be used to evaluate the risk of HIV infection in MSM, but the specificity should be improved.

Neurodevelopmental disorder caused by a truncating de novo variant of IRF2BPL

BACKGROUND

Mutations in the IRF2BPL gene can cause neurodevelopmental disorders. We describe the clinical and genetic characteristics of a Chinese patient with a novel abnormality in this gene, explore the potential pathogenic mechanism and summarize the clinical characteristics of 25 patients with IRF2BPL mutations.

METHODS

We identified the gene mutation sites by whole-exome and Sanger sequencing. The protein-protein interaction network of the IRF2BPL gene was constructed using bioinformatic techniques, and its function was enriched. We conducted a functional experiment to explore the potential pathogenicity of the identified IRF2BPL gene mutation.

RESULTS

An 8-year-old girl presented with progressive cerebellar ataxia, including involuntary tremor and slurred speech. Electroencephalography and electromyography revealed no abnormalities. Structural cranial MRI was also normal, but genetic analysis identified a truncating de novo variant in IRF2BPL. Bioinformatics predicted that IRF2BPL would be associated with IRF2 and 10 other genes and involved in ubiquitin binding and other pathways. The cellular location of IRF2BPL was altered, and compared to control cells, the level of ubiquitinated proteins was significantly decreased in cells harbouring the mutation.

CONCLUSION

In this study, we identified a truncating de novo variant of IRF2BPL as a causative gene in the neurodevelopmental disorder of a Chinese girl. Impairment of the ubiquitin-proteasome pathway caused by this IRF2BPL mutation may play an important role in this neurodevelopmental disorder.

Fetal hemoglobin induction by the histone deacetylase inhibitor, scriptaid

Many different classes of drugs induce fetal hemoglobin (HbF) including histone deacetylase (HDAC) inhibitors such as butyrate and trichostatin A. Although these agents induce gamma-globin expression in culture many are ineffective in vivo, therefore research efforts continue to identify clinically useful fetal globin inducers. We and others demonstrated a role for p38 mitogen activated protein kinase (MAPK) in gamma-globin promoter activation by HDAC inhibitors. In this study we determined the ability of scriptaid, a novel HDAC inhibitor, to induce gamma-globin expression via p38 MAPK signaling. Scriptaid induced gamma-globin in K562 cells and human erythroid progenitors. Furthermore the p38-selective inhibitor SB203580 completely reversed the ability of scriptaid to induce HbF. To test the potential efficacy of scriptaid in humans, in vivo studies were completed in beta-YAC transgenic mice where the gamma-gene is completely silenced. Scriptaid induced reticulocytosis and human gamma-globin mRNA synthesis. At a concentration of 1 mg/kg/day given by intraperitoneal injections twice weekly we observed a significant 1.8-fold increase in gamma-globin mRNA transcripts. The potential for scriptaid as a treatment option for sickle cell disease will be discussed.

HBx protein of hepatitis B virus (HBV) can form complex with mitochondrial HSP60 and HSP70

HBx, a transcriptional transactivating protein of hepatitis B virus (HBV), is required for viral infection and has been implicated in virus-mediated liver oncogenesis. However, the molecular mechanism for its influence on cell remains largely unknown. It was proved that HBx need the help of host cell proteins to exert its function by binding to them. During purifying of GSTX (fusion protein of GST and HBx) expressed in E. coli, we found that it can bind specifically with GrpE (HSP60) and DnaK (HSP70) of E. coli while GST cannot. Using GST pull-down, two-dimensional gel electrophoresis and mass spectrum, we found that GSTX can also bind to human mitochondrial HSP60 and HSP70, which are homologues of GrpE and DnaK. These interactions between HBx and mitochondrial HSP60 and HSP70 are supported by the result of co-immunoprecipitation experiment. It means that HBx can form complex with E. coli and human HSP60 and HSP70. The implication of HBx, HSP60 and HSP70 complex in molecular mechanism of virus infection is discussed.

Aplastic anaemia associated with parvovirus B19 infection

Parvovirus B19 involvement was investigated in 30 children with severe aplastic anaemia. Active or recent parvovirus B19 infection, as shown by B19 DNA viraemia, positive B19 specific IgM antibodies, or both, was diagnosed in six patients. There were no other plausible causes. We suggest that parvovirus B19 infection might be associated with severe aplastic anaemia.

[The spectroscopic study of the iodine beta-cyclodextrin complexes]

In this paper, the iodine beta-cyclodextrin complexes prepared in different techniques were investigated by Fourier transformation infrared spectrum(FTIR), FT-Raman, Ultra-violet absorption spectrum in qualitative and quantitative analysis. Results showed that the iodine existed in dissociated, bundle and polymerized forms in the complexes. Contras to the method of alcohol craft, the sample prepared in water craft method included a higher capacity of iodine, but it was not stable enough to keep a constant high iodine concentration. This analysis method was simple and convenient, it is useful for quality control of the iodine beta-cyclodextrin complexes raw material medicine.

Affinity capillary electrophoresis investigation of an epitope on human immunodeficiency virus recognized by a monoclonal antibody

Affinity capillary electrophoresis (ACE) has been used to investigate the epitope on the human immunodeficiency virus (HIV) core protein p24 recognized by the monoclonal antibody (mAb) 13-102-100. The affinity of a series of peptides with N- and C-terminal truncations of the epitope sequence determined by mass spectrometry was studied. The peak area change assay was used for the study of the interactions of the mAb with those peptides, exhibiting tight binding to the mAb, and the migration time shift assay was used to probe the relative affinities of peptides showing weak binding to the mAb. The experimental results show that the monoclonal antibody 13-102-100 recognizes the peptide VHPVHAGPIAP with highest affinity. Smaller peptides incorporating only part of the epitope, however, are recognized to some extent in the ACE experiments.

[Lactate and glucose determination using biosensors in umbilical cord blood]

Postpartal determination of lactate and glucose in the umbilical cord whole blood of 139 successive deliveries utilizing biosensors (blood gas analysator 865, Ciba Corning) are presented. The median lactate value in the umbilical arterial blood is 4.45 mmol/l and in the venous blood 4.23 mmol/l. Following categorization into control and high-risk groups, the arterial mean values are 4.23 mmol/l and 6.39 mmol/l and the respective venous values are 3.95 mmol/l and 5.04 mmol/l. Using the U-test these differences between the control and high-risk groups are significant. The mean of the measured lactate correlates significantly with the mean of the calculated base excess (< 0.001). The mean glucose value in the umbilical arterial blood is 78 mg/dl and in the venous 93 mg/dl. Between high-risk and control group no significant difference is found.

Inhibition of breast cancer progression by an antibody to a thrombospondin-1 receptor

BACKGROUND

Thrombospondin-1 (TSP-1) is a matrix-bound adhesive glycoprotein. Breast carcinoma cells exhibit increased expression of a novel TSP-1 receptor. We evaluated the role of this receptor in breast cancer adhesion and progression.

METHODS

Adhesion assays were performed to evaluate MDA-MB-231 breast cancer cell adhesion to TSP-1 in vitro in the presence of either nonimmune immunoglobulin G(IgG) or anti-TSP-1 receptor IgG. Receptor-mediated tumor cell progression was evaluated in athymic nude mice. Mice were inoculated with MDA-MB-231 breast cancer cells and randomized to treatment with intraperitoneal injections of saline solution, nonspecific IgG antibody, or an anti-TSP-1 receptor antibody every other day for 20 days. Mice were killed at 21 days. The peritoneal cavity was examined grossly for primary tumor implantation. The liver and lungs were examined histologically for micrometastases.

RESULTS

MDA-MB-231 breast cancer cells adhered to TSP-1 in vitro. This adhesion was inhibited to 10% of control by anti-TSP-1 receptor antibody (p < 0.005). Anti-TSP-1 receptor antibody inhibited in vivo breast cancer progression. Mice treated with control IgG antibody or saline solution alone exhibited extensive intraperitoneal seeding. Only one mouse treated with the anti-TSP-1 receptor antibody exhibited any intraperitoneal tumor seeding (p < 0.01).

CONCLUSIONS

These data suggest that TSP-1 and its receptor play an important role in breast cancer progression.

The effect of thrombospondin on oral squamous carcinoma cell invasion of collagen

BACKGROUND

Thrombospondin (TSP), a cell matrix protein, and transforming growth factor beta (TGF-beta), a growth regulatory protein, play roles in tumor progression. The purpose of this study was to investigate the effects of TSP and TGF-beta on tumor cell invasion.

MATERIALS AND METHODS

Tumor cell invasion assays were performed using a modified Boyden chamber apparatus with collagen-coated membranes. The KB oral carcinoma cell line was studied in serum-free media. Invasion was measured as the summation of the number of cells in five representative low-power fields (x 100) traversing the collagen barrier after a 3-hour incubation period. The effects of antibodies against TSP, TGF-beta and the cysteine-serine-valine-threonine-cysteine-glycine (CSVTCG)-specific TSP receptor were also evaluated.

RESULTS

TSP caused a dose-dependent stimulation of tumor cell invasion. Antibodies against TSP, its CSVTCG-specific receptor, and TGF-beta inhibited TSP-promoted invasion by 50% to 71%.

CONCLUSIONS

TSP and its CSVTCG-specific receptor promote KB cell invasion of collagen through the production and/or activation of TGF-beta.

Asymmetry in active complexes of FLP recombinase

The FLP recombinase promotes a site-specific recombination reaction in the 2mu plasmid of yeast. The protein-DNA complex that carries out the reaction is asymmetric. Three FLP monomers bound to specific FLP-recognition sequences are required to efficiently carry out one set of reciprocal DNA cleavage and strand exchange events on a Holliday junction substrate. If a fourth monomer plays an auxiliary role in the reaction, it is bound without sequence specificity. The data suggest a modified model for cleavage of DNA in trans by the FLP recombinase that might help reconcile some seemingly conflicting resulted obtained with integrase class recombinases.

Detection of the BCR/ABL fusion gene in chronic myeloid leukemia by RNA polymerase chain reaction

The bcr/abl fusion gene in 20 patients with chronic myeloid leukemia (CML) was detected by RNA polymerase chain reaction, which used mRNA as the starting material to generate cDNA with reverse transcriptase followed by PCR amplification (RNA/PCR). Amplification of a sequence spanning the bcr/abl junction region was achieved by using peripheral blood cells as the source of mRNA from all 20 patients with CML, including 3 cases of Ph (-) CML, and cell line K562 was derived from patients with CML. No amplification was seen when mononuclear cells from 3 normal individuals, 2 patients with lymphoma and cell line HL-60 were used. The presence or absence of bcr exon 3 in the fusion mRNA was determined by the size of the amplified fragments. Of the 20 CML patients, 15 showed only the 165-bp amplified band (indicating retention of bcr exon 3), one showed only the 90-bp amplified band, and 4 showed both 165-bp and 90-bp bands. Both bands were seen more frequently in blast crisis than in remission and chronic phase.

[Monitoring of maternal-fetal hepatitis B virus transmission by molecular hybridization technique]

Maternal venous blood (MB), umbilical blood (UB) and placental tissue (PT) were collected from 40 HBsAg positive mothers and their neonates, and also blood from 17 babies aged 3-6 months old of this group (BB). All samples were determined for hepatitis B virus (HBV) DNA by molecular hybridization technique using Bio-HBV DNA probe. The results showed: HBV DNA positive rate of MB was 35.0%, 47.5% for UB, 75.0% for PT and 29.4% for BB. 32 P-HBV DNA probe was also used to examine MB and PT. The positive rates of HBV DNA were 30.0% and 70.0% respectively. There was no significant difference between the results of the 2 probes. We considered: (1) With the rapid development of HBV detection technique, the detectable rate of intrauterine infection increases accordingly. (2) Besides transplacental infection, other transmission routes might be existed. (3) The detection of HBV DNA in UB, PT and in the blood of babies born by HBV DNA positive mother within 6 months old provides the reliable diagnosis. (4) HBV DNA molecular hybridization is an accurate and sensitive method for the diagnosis of HBV intrauterine infection.

Reactions between half- and full-FLP recombination target sites. A model system for analyzing early steps in FLP protein-mediated site-specific recombination

The FLP recombination target (FRT) can be cut in half so that only one FLP protein binding site is present (a "half site"). FLP protein binds the half sites and joins them into dimeric, asymmetric head-to-head complexes held together chiefly by strong noncovalent interactions. These complexes react with full (normal) FRT sites to generate a variety of products. Analysis of these DNA species reveals that the reaction follows a well-defined reaction pathway that generally parallels the normal reaction pathway. The system is useful in analyzing early steps in recombination, since the identity of the products in a given recombination event unambiguously pinpoints the order in which the cleavage and strand exchange reactions occur. Two conclusions are derived from the present study: (i) Formation of the dimeric head-to-head complex of half sites is a prerequisite to further steps in recombination. (ii) The identity of the base pairs at positions 6 and -6 within the FRT site has a subtle effect in directing the first strand exchange event in the reaction to predominantly one of two possible cleavage sites. In addition, results are presented that suggest that a DNA-DNA pairing intermediate involving only two base pairs of the core sequence is formed prior to the first cleavage and strand exchange. DNA-DNA interactions may therefore not be limited to the isomerization step that follows the first strand exchange.

[Treatment of hypertension syndrome of pregnancy with ligustrazine]

75 patients with hypertension syndrome of pregnancy (HSP) were randomly designed to 2 groups: the control group treated with magnesium sulfate (20-25g/d) and the Ligustrazine (120-160mg/d) group. The results of Ligustrazine group compared with the control group were as follows: (1) Mean arterial pressure was significantly decreased (P less than 0.01). (2) Edema and proteinuria was lowered (P less than 0.05). (3) The condition of rheology was improved, especially, hematocrit was significantly decreased (P less than 0.001). (4) The positive rate of NST and Apgar's score were not different between the 2 groups. Clinical monitoring showed Ligustrazine without side effects in the group. Mechanisms of Ligustrazine in HSP were (1) dilating blood vessel; (2) improving kidney function; (3) improving microcirculatory and rheology.

Fibrinolytic enzyme from Agkistrodon halys brevicaudus (Korean mamushi) snake venom

By means of DEAE-Sepharose CL-6B ion exchange chromatography and TSK-GEL G2000 SW high-performance gel filtration, a purified protein with fibrinolytic activity was obtained from the venom of Agkistrodon halys brevicaudus (Korean mamushi). The protein was homogeneous as judged by isoelectric focusing electrophoresis and high-performance gel filtration. Its mol. wt is 39,200 and its isoelectric point 4.12. The specific fibrinolytic activity of the protein was 3.2 times higher than that of the crude venom. The fibrinolytic activity of the purified principle was 33 units/mg protein (units of standard urokinase activity).

Protein-based asymmetry and protein-protein interactions in FLP recombinase-mediated site-specific recombination

When the FLP recombination target (FRT) is cut in half so that only one FLP protein-binding site is present, FLP protein forms a complex in which two such sites are linked head to head. Although held together exclusively by noncovalent interactions, this complex survives electrophoresis in an agarose gel and exhibits a half-life that can be measured in hours. Characterization of this complex indicates that a very stable, asymmetric dimeric complex of FLP protein monomers bound to the FRT is a likely early intermediate in FLP-mediated site-specific recombination. The apparent asymmetry is a property of the protein components of the complex. Even though the DNA components form a perfect palindrome, only one of the two possible DNA cleavage steps takes place in the course of complex formation. Formation of this complex does not occur with half-FRT site DNA substrates that preclude head to head monomer contact or when a FLP mutant protein is used that binds the FRT site but cannot cleave it. Trimeric and tetrameric complexes are also observed, the latter at very low frequency. These results are discussed in terms of an expanded model for early events in FLP-mediated site-specific recombination.