Hypothetical chloroplast reading frame 51 encodes a photosystem I assembly factor in cyanobacteria.

Hypothetical chloroplast open reading frames (ycfs) are putative genes in the plastid genomes of photosynthetic eukaryotes. Many ycfs are also conserved in the genomes of cyanobacteria, the presumptive ancestors of present-day chloroplasts. The functions of many ycfs are still unknown. Here, we generated knock-out mutants for ycf51 (sll1702) in the cyanobacterium Synechocystis sp. PCC 6803. The mutants showed reduced photoautotrophic growth due to impaired electron transport between photosystem II (PSII) and PSI. This phenotype results from greatly reduced PSI content in the ycf51 mutant. The ycf51 disruption had little effect on the transcription of genes encoding photosynthetic complex components and the stabilization of the PSI complex. In vitro and in vivo analyses demonstrated that Ycf51 cooperates with PSI assembly factor Ycf3 to mediate PSI assembly. Furthermore, Ycf51 interacts with the PSI subunit PsaC. Together with its specific localization in the thylakoid membrane and the stromal exposure of its hydrophilic region, our data suggest that Ycf51 is involved in PSI complex assembly. Ycf51 is conserved in all sequenced cyanobacteria, including the earliest branching cyanobacteria of the Gloeobacter genus, and is also present in the plastid genomes of glaucophytes. However, Ycf51 has been lost from other photosynthetic eukaryotic lineages. Thus, Ycf51 is a PSI assembly factor that has been functionally replaced during the evolution of oxygenic photosynthetic eukaryotes.

Case report: genetic analysis of a novel frameshift mutation in FMR1 gene in a Chinese family.

Fragile X syndrome (FXS) [OMIM 300624] is a common X-linked inherited syndrome with an incidence only second to that of trisomy 21. More than 95% of fragile X syndrome is caused by reduced or absent fragile X intellectual disability protein 1 (FMRP) synthesis due to dynamic mutation expansion of the CGG triplet repeat in the 5'UTR and abnormal methylation of the FMR1 (fragile X messenger ribonucleoprotein 1) gene [OMIM 309550]. Less than 5% of cases are caused by abnormal function of the FMRP due to point mutations or deletions in the FMR1 gene. In a proband with clinical suspicion of FXS and no CGG duplication, we found the presence of c.585_586del (p.Lys195AsnfsTer8) in exon 7 of the FMR1 gene using whole exome sequencing (WES). This variant resulted in frameshift and a premature stop codon after 8 aberrant amino acids. This variant is a novel pathogenic mutation, as determined by pedigree analysis, which has not been reported in any database or literature.

Safety and Clinical Activity of SHR7390 Monotherapy or Combined With Camrelizumab for Advanced Solid Tumor: Results From Two Phase I Trials.

BACKGROUND: SHR7390 is a novel, selective MEK1/2 inhibitor. Here, we report results from two phase I trials conducted to evaluate the tolerability, safety and antitumor activity of SHR7390 monotherapy for advanced solid tumors and SHR7390 plus camrelizumab for treatment-refractory advanced or metastatic colorectal cancer (CRC). PATIENTS AND METHODS: Patients received SHR7390 alone or combined with fixed-dose camrelizumab (200 mg every 2 weeks) in an accelerated titration scheme to determine the maximum tolerated dose (MTD). A recommended dose for expansion was determined based on the safety and tolerability of the dose-escalation stage. The primary endpoints were dose limiting toxicity (DLT) and MTD. RESULTS: In the SHR7390 monotherapy trial, 16 patients were enrolled. DLTs were reported in the 1.0 mg cohort, and the MTD was 0.75 mg. Grade ≥3 treatment-related adverse events (TRAEs) were recorded in 4 patients (25.0%). No patients achieved objective response. In the SHR7390 combination trial, 22 patients with CRC were enrolled. One DLT was reported in the 0.5 mg cohort and the MTD was not reached. Grade ≥3 TRAEs were observed in 8 patients (36.4%), with the most common being rash (n=4). One grade 5 TRAE (increased intracranial pressure) occurred. Five patients (22.7%) achieved partial response, including one of 3 patients with MSS/MSI-L and BRAF mutant tumors, one of 15 patients with MSS/MSI-L and BRAF wild type tumors, and all 3 patients with MSI-H tumors. CONCLUSIONS: SHR7390 0.5 mg plus camrelizumab showed a manageable safety profile. Preliminary clinical activity was reported regardless of MSI and BRAF status.

Rezvilutamide versus bicalutamide in combination with androgen-deprivation therapy in patients with high-volume, metastatic, hormone-sensitive prostate cancer (CHART): a randomised, open-label, phase 3 trial.

BACKGROUND: Rezvilutamide, a novel androgen-receptor inhibitor with low blood-brain barrier penetration, has shown potent antitumour activity against metastatic castration-resistant prostate cancer. In this study, we aimed to evaluate the efficacy and safety of rezvilutamide versus bicalutamide in combination with androgen-deprivation therapy (ADT) for high-volume, metastatic, hormone-sensitive prostate cancer. METHODS: CHART is a randomised, open-label, phase 3 study done at 72 hospitals in China, Poland, Czech Republic, and Bulgaria. Eligible patients were aged 18 years or older, had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and had high-volume metastatic, hormone-sensitive prostate cancer. Previous chemotherapy or other localised treatment for prostate cancer were not allowed. Patients were randomly assigned (1:1) to receive ADT plus either rezvilutamide (240 mg) or bicalutamide (50 mg) orally once daily. Randomisation was done via an interactive response technology system (block size of four) and stratified according to ECOG performance status and presence of visceral metastasis (excluding lymph nodes). Herein, we present the results of the preplanned interim analyses for the two co-primary endpoints of radiographic progression-free survival assessed by a blinded independent review committee and overall survival in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study medication. This study is ongoing, but is closed to recruitment. This trial is registered with ClinicalTrials.gov, NCT03520478. FINDINGS: Between June 28, 2018, and Aug 6, 2020, 792 patients were screened and 654 patients were randomly assigned to receive rezvilutamide plus ADT (n=326) or bicalutamide plus ADT (n=328). At the preplanned interim analysis for radiographic progression-free survival (data cutoff May 16, 2021), the median follow-up duration was 21·2 months (IQR 16·6-25·8). Rezvilutamide significantly improved radiographic progression-free survival compared with bicalutamide (median radiographic progression-free survival not reached [95% CI not reached-not reached] vs 25·1 months [95% CI 15·7-not reached]; hazard ratio [HR] 0·44 [95% CI 0·33-0·58]; p<0·0001). At the preplanned interim analysis for overall survival (data cutoff Feb 28, 2022), the median follow-up duration was 29·3 months (IQR 21·0-33·3). Rezvilutamide significantly improved overall survival compared with bicalutamide (HR 0·58 [95% CI 0·44-0·77]; p=0·0001; median overall survival was not reached [95% CI not reached-not reached] vs not reached [36·2-not reached]). The most common grade 3 or worse adverse events of any cause in the safety population were hypertension (26 [8%] of 323 patients in the rezvilutamide group vs 24 [7%] of 324 patients in the bicalutamide group), hypertriglyceridaemia (24 [7%] vs seven [2%]), increased weight (20 [6%] vs 12 [4%]), anaemia (12 [4%] vs 16 [5%]), and hypokalaemia (11 [3%] vs four [1%]). Serious adverse events were reported in 90 (28%) of 323 patients in the rezvilutamide group and 69 (21%) of 324 patients in the bicalutamide group. No treatment-related deaths occurred in patients in the rezvilutamide group; one treatment-related death of unknown specific cause (<1%) occurred in the bicalutamide group. INTERPRETATION: In the two interim analyses, rezvilutamide plus ADT significantly improved radiographic progression-free survival and overall survival compared with bicalutamide plus ADT in patients with high-volume, metastatic, hormone-sensitive prostate cancer, with a tolerable safety profile. FUNDING: Jiangsu Hengrui Pharmaceuticals.

Activity and safety of SHR3680, a novel antiandrogen, in patients with metastatic castration-resistant prostate cancer: a phase I/II trial.

BACKGROUND: Antagonizing the androgen-receptor (AR) pathway is an effective treatment strategy for patients with metastatic castration-resistant prostate cancer (CRPC). Here, we report the results of a first-in-human phase 1/2 study which assessed the safety, pharmacokinetics, and activity of SHR3680 (a novel AR antagonist) in patients with metastatic CRPC. METHODS: This phase 1/2 study enrolled patients with progressive metastatic CRPC who had not been previously treated with novel AR-targeted agents. In the phase 1 dose-escalation portion, patients received oral SHR3680 at a starting daily dose of 40 mg, which was subsequently escalated to 80 mg, 160 mg, 240 mg, 360 mg, and 480 mg per day. In phase 2 dose-expansion portion, patients were randomized to receive daily dose of 80 mg, 160 mg, or 240 mg of SHR3680. The primary endpoint in phase 1 was safety and tolerability and in phase 2 was the proportion of patients with a prostate-specific antigen (PSA) response (≥ 50% decrease of PSA level) at week 12. RESULTS: A total of 197 eligible patients were enrolled and received SHR3680 treatment, including 18 patients in phase 1 and 179 patients in phase 2. No dose-limiting toxicities were reported and the maximum tolerated dose was not reached. Treatment-related adverse events (TRAEs) occurred in 116 (58.9%) patients, with the most common one being proteinuria (13.7%). TRAEs of grade ≥ 3 occurred in only 23 (11.7%) patients, and no treatment-related deaths occurred. Antitumor activities were evident at all doses, including PSA response at week 12 in 134 (68.0%; 95% CI, 61.0-74.5) patients, stabilized bone disease at week 12 in 174 (88.3%; 95% CI, 87.2-95.5) patients, and responses in soft tissue lesions in 21 (34.4%, 95% CI, 22.7-47.7) of 61 patients. CONCLUSION: SHR3680 was well tolerated and safe, with promising anti-tumor activity across all doses tested in patients with metastatic CRPC. The dose of 240 mg daily was recommended for further phase 3 study. TRIAL REGISTRATION: Clinical trials.gov NCT02691975; registered February 25, 2016.

Apatinib as second-line or later therapy in patients with advanced hepatocellular carcinoma (AHELP): a multicentre, double-blind, randomised, placebo-controlled, phase 3 trial.

BACKGROUND: Inhibition of vascular endothelial growth factor receptor (VEGFR) has shown antitumour activity in advanced hepatocellular carcinoma, but few studies of VEGFR inhibitors have been done in populations with a high prevalence of hepatitis B virus infection. The aim of this study was to evaluate the efficacy and safety of apatinib in patients with pretreated advanced hepatocellular carcinoma. METHODS: AHELP was a randomised, double-blind, placebo-controlled, phase 3 trial done at 31 hospitals in China, in patients (aged ≥18 years) with advanced hepatocellular carcinoma who had previously been refractory or intolerant to at least one line of systemic chemotherapy or targeted therapy. Patients were randomly assigned (2:1) to receive apatinib 750 mg or placebo orally once daily in 28-day treatment cycles. Group allocation was done with a central randomisation system, with a block size of six, and was stratified by Eastern Cooperative Oncology Group performance status, previous sorafenib treatment, and presence of vascular invasion or extrahepatic metastasis. The primary endpoint was overall survival, which was defined as time from randomisation to death from any cause, and was analysed in patients who were randomly assigned and received at least one dose of the study drug. Safety analyses were done in patients who received at least one dose of the study treatment and had post-dose safety assessments. This trial is registered with ClinicalTrials.gov, NCT02329860. FINDINGS: Between April 1, 2014, and May 3, 2017, 400 eligible patients were randomly assigned to receive apatinib (n=267) or placebo (n=133). Seven patients (six in the apatinib group and one in the placebo group) did not receive study treatment and were excluded from efficacy analyses. Overall survival was significantly improved in the apatinib group compared with the placebo group (median 8·7 months [95% CI 7·5‒9·8] vs 6·8 months [5·7‒9·1]; hazard ratio 0·785 [95% CI 0·617‒0·998], p=0·048). 387 patients (257 in the apatinib group and 130 in the placebo group) had a safety assessment after study treatment and were included in safety analyses. The most common treatment-related adverse events of grade 3 or 4 were hypertension (71 [28%] patients in the apatinib group vs three [2%] in the placebo group), hand-foot syndrome (46 [18%] vs none), and decreased platelet count (34 [13%] vs one [1%]). 24 (9%) patients in the apatinib group and 13 (10%) in the placebo group died due to adverse events, but none of these deaths were deemed to be related to treatment by investigators. INTERPRETATION: Apatinib significantly improved overall survival in patients with pretreated advanced hepatocellular carcinoma compared with placebo, with a manageable safety profile. FUNDING: Jiangsu Hengrui Medicine.

Case Report: Prenatal Diagnosis of a Fetus With Harlequin Ichthyosis Identifies Novel Compound Heterozygous Variants: A Case Report.

BACKGROUND: Harlequin ichthyosis (HI) is the most severe form of the keratinizing disorders, and it is characterized by whole-body hard stratum corneum. ABCA12 has been identified as the major disease-causing gene of HI. METHODS: A case of HI was prenatally diagnosed by ultrasonography and genetic tests. The fetus had been found with dentofacial deformity and profound thickening of the palm and plantar soft tissues. Chromosomal microarray analysis (CMA) and whole exome sequencing (WES) were then performed on the amniotic fluid to identify germline pathogenic variants for the fetus. Candidate variants were verified by Sanger sequencing. RESULTS: Compound heterozygous frameshift variants (p.Q719QfsX21; p.F2286LfsX6) of ABCA12 were identified for the fetus, suggesting the former variants were maternally inherited and the latter paternally inherited. The fetus was terminated. CONCLUSION: A prenatal molecular diagnosis is an important approach for the prevention of HI. In the study, we provided a successful case of genetic counseling for a family with an HI baby.

Paternal Low-Level Mosaicism-Caused SATB2-Associated Syndrome.

Mutations of SATB2 (OMIM#608148) gene at 2q33.1 have been associated with the autosomal dominant SATB2-associated syndrome (SAS), which is still short of comprehensive diagnosis technologies for small deletions and low-level mosaicism. In this Chinese Han family, single nucleotide polymorphism array identified a 4.9-kb deletion in the SATB2 gene in two consecutive siblings exhibiting obvious developmental delay and dental abnormalities but failed to find so in their parents. Prenatal diagnosis revealed that their third child carried the same deletion in SATB2 and the pregnancy was terminated. To determine the genetic causes behind the inheritance of SATB2 deletion, gap-PCR was performed on peripheral blood-derived genomic DNA of the family and semen-derived DNA from the father. Gap-PCR that revealed the deletions in the two affected siblings were inherited from the father, while the less intense mutant band indicated the mosaicism of this mutation in the father. The deletion was 3,013 bp in size, spanning from chr2: 200,191,313-200,194,324 (hg19), and covering the entire exon 9 and part of intron 8 and 9 sequences. Droplet digital PCR demonstrated mosaicism percentage of 13.2% and 16.7% in peripheral blood-derived genomic DNA and semen-derived DNA of the father, respectively. Hereby, we describe a family of special AT-rich sequence-binding protein 2-associated syndrome caused by paternal low-level mosaicism and provide effective diagnostic technologies for intragenic deletions.

[Phenotypic and genetic analysis of a sibpair with partial deletion of SATB2 gene caused by 2q33.1 microdeletion].

OBJECTIVE: To analyze the genotype and phenotype of a sibpair with partial deletion of SATB2 gene caused by 2q33.1 microdeletion. METHODS: Both children have featured mental retardation and development delay, and were subjected to karyotyping, single nucleotide microarray (SNP array) and real-time fluorescence quantitative PCR analysis. Karyotyping and SNP Array analysis were also carried out on their parents to verify the origin of mutation. RESULTS: Both sibs had a normal karyotype. SNP array showed that sib 1 had arr[hg19]2q33.1(200 192 328 - 200 197 269)×1 (4.9 kb), 2q35 (218 105 663 - 218 816 675)×3 (711 kb), while sib 2 had arr[hg19]2q33.1(200 192 328 - 200 197 269)×1 (4.9 kb), 2q35 (218 105 663-218 810 908)×3 (705.2 kb). The deletion has partially overlapped with that of 2q33.1 microdeletion syndrome and involved part of the SATB2 gene. The result of real-time fluorescence quantitative PCR assay was consistent with that of SNP assay. The duplication has originated from their father and has not been associated with any disease phenotypen. CONCLUSION: Both sibs have carried partial deletion of SATB2 gene and had similar clinical phenotypes. Haploinsufficiency of such gene probably underlies the clinical manifestations in both patients.

[Prenatal diagnosis and pregnancy outcomes of 22q11.2 duplication syndrome: analysis of 8 cases].

OBJECTIVE: To investigate the relationship between 22q11.2 duplication and clinical phenotype. METHODS: Eight fetuses with 22q11.2 duplication syndrome diagnosed by chromosome microarray analysis (CMA) through amniocentesis from February 2015 to March 2017 were enrolled in the study. The prenatal diagnostic indications, fetal ultrasound, chromosome karyotype, peripheral blood CMA results of parents, pregnancy outcomes and follow-up of postnatal growth and development were retrospectively analyzed. RESULTS: Prenatal serological screening indicated 6 cases with high risk of trisomy 21, 1 case with nuchal fold (NF) thickening and 1 case of maternal chromosomal balanced translocation. Fetal ultrasonography showed 1 case of NF thickening, 1 case of fetal cerebral ventriculomegaly and 6 cases with normal ultrasound. CMA demonstrated that the size of duplication was between 651 kb and 3.26 Mb, and 22q11.2 duplication. Parents' CMA results revealed that 6 cases inherited from one of the parents with normal phenotype, and the parents of 2 cases refused the CMA test. Two couples chose induced labor; 6 cases of continued pregnancy had normal phenotypes at birth. All 6 cases were followed up with longest of 3.5 years. The growth and psychological development were normal in 5 cases, and one case was growth retardation. CONCLUSIONS: There were no specific clinical phenotypes in 22q11.2 duplication syndrome, and most of them were inherited from one parent who has normal phenotype.

[Application of BACs-on-Beads and karyotyping for the prenatal diagnosis of 1371 pregnant women with a high risk].

OBJECTIVE: To assess the value of combined BACs-on-BeadsTM (BoBs) and chromosomal karyotyping for the diagnosis of women with high-risk pregnancy. METHODS: For 1371 women with singleton pregnancy and various indications for prenatal diagnosis, karyotyping and BoBs were simultaneously applied on their amnionic fluid samples. RESULTS: In total 23 cases of trisomy 21, 11 cases of trisomy 18, 5 cases of sex chromosome aneuploidies, 6 cases of microdeletions/microduplications, 2 cases of chimeric chromosomes and 1 case of structural chromosomal abnormality were detected by the BoBs assay, among which the 6 microdeletions/microduplications were not detected by karyotyping. Karyotyping analysis has identified an extra yield of 19 chromosomal abnormalities and 34 chromosomal polymorphisms. CONCLUSION: Combined use of BoBs and chromosomal karyotyping can improve the detection rate of fetal chromosomal abnormalities including microdeletions/microduplications, which should find a wider use in the clinics.

Minimal role of base excision repair in TET-induced global DNA demethylation in HEK293T cells.

Oxidation of 5-methylcytosine by TET family proteins can induce DNA replication-dependent (passive) DNA demethylation and base excision repair (BER)-based (active) DNA demethylation. The balance of active vs. passive TET-induced demethylation remains incompletely determined. In the context of large scale DNA demethylation, active demethylation may require massive induction of the DNA repair machinery and thus compromise genome stability. To study this issue, we constructed a tetracycline-controlled TET-induced global DNA demethylation system in HEK293T cells. Upon TET overexpression, we observed induction of DNA damage and activation of a DNA damage response; however, BER genes are not upregulated to promote DNA repair. Depletion of TDG (thymine DNA glycosylase) or APEX1 (apurinic/apyrimidinic endonuclease 1), two key BER enzymes, enhances rather than impairs global DNA demethylation, which can be explained by stimulated proliferation. By contrast, growth arrest dramatically blocks TET-induced global DNA demethylation. Thus, in the context of TET-induction in HEK293T cells, the DNA replication-dependent passive mechanism functions as the predominant pathway for global DNA demethylation. In the same context, BER-based active demethylation is markedly restricted by limited BER upregulation, thus potentially preventing a disastrous DNA damage response to extensive active DNA demethylation.

Epigenetic synergy between decitabine and platinum derivatives.

BACKGROUND: Aberrant epigenetic silencing of tumor suppressor genes has been recognized as a driving force in cancer. Epigenetic drugs such as the DNA methylation inhibitor decitabine reactivate genes and are effective in myeloid leukemia, but resistance often develops and efficacy in solid tumors is limited. To improve their clinical efficacy, we searched among approved anti-cancer drugs for an epigenetic synergistic combination with decitabine. RESULTS: We used the YB5 cell line, a clonal derivative of the SW48 colon cancer cell line that contains a single copy of a hypermethylated cytomegalovirus (CMV) promoter driving green fluorescent protein (GFP) to screen for drug-induced gene reactivation and synergy with decitabine. None of the 16 anti-cancer drugs tested had effects on their own. However, in combination with decitabine, platinum compounds showed striking synergy in activating GFP. This was dose dependent, observed both in concurrent and sequential combinations, and also seen with other alkylating agents. Clinically achievable concentrations of carboplatin at (25 µM) and decitabine reactivated GFP in 28 % of the YB5 cells as compared to 15 % with decitabine alone. Epigenetic synergy was also seen at endogenously hypermethylated tumor suppressor genes such as MLH1 and PDLIM4. Genome-wide studies showed that reactivation of hypermethylated genes by the combination was significantly better than that induced by decitabine alone or carboplatin alone. Platinum compounds did not enhance decitabine-induced hypomethylation. Rather, we found significantly inhibited HP1α expression by carboplatin and the combination. This was accompanied by increased histone H3 lysine 4 (H3K4) trimethylation and histone H3 lysine 9 (H3K9) acetylation at reactivated genes (P < 0.0001) and reduced occupancy by methyl-binding proteins including MeCP2 and methyl-CpG-binding domain protein 2 (MBD2) (P < 0.0001). CONCLUSIONS: Our results suggest that the combination of decitabine with platinum analogs shows epigenetic synergy that might be exploited in the treatment of different cancers.

Aberrant Wnt/ß-catenin signaling and elevated expression of stem cell proteins are associated with osteosarcoma side population cells of high tumorigenicity.

According to the cancer stem cell theory, the presence of a small sub­population of cancer cells, termed cancer stem cells (CSCs), have a significant implication on cancer treatment and are responsible for tumor recurrence. Previous studies have reported that alterations in the Wnt/ß­catenin signaling are crucial in the maintenance of CSCs. In the present study, the characteristic features and activation of Wnt/ß­catenin signaling in CSCs from osteosarcoma, an aggressive human bone tumor, were investigated. In total, ~2.1% of the cancer stem­like side population (SP) cells were identified in the osteosarcoma samples. The results of subsequent western blot and reverse transcription­quantitative polymerase chain reaction analyses revealed that the protein levels of ß­catenin and cyclin D1 were markedly upregulated in the fluorescence­activated cell sorted osteosarcoma SP cells. In addition, the elevated expression levels of stem cell proteins, including CD133, nestin Oct­4, Sox­2 and Nanog were significantly higher in the SP cells, which contributed to self­renewal and enhanced the proliferation rate of the SP cells. Furthermore, the SP cells were found to be highly invasive and able to form tumors in vivo. Taken together, these data suggested that the identification of novel anticancer drugs, which suppress the Wnt/ß­catenin signaling and its downstream pathway may assist in eradicating osteosarcoma stem cells.

TET1 is a maintenance DNA demethylase that prevents methylation spreading in differentiated cells.

TET1 is a 5-methylcytosine dioxygenase and its DNA demethylating activity has been implicated in pluripotency and reprogramming. However, the precise role of TET1 in DNA methylation regulation outside of developmental reprogramming is still unclear. Here, we show that overexpression of the TET1 catalytic domain but not full length TET1 (TET1-FL) induces massive global DNA demethylation in differentiated cells. Genome-wide mapping reveals that 5-hydroxymethylcytosine production by TET1-FL is inhibited as DNA methylation increases, which can be explained by the preferential binding of TET1-FL to unmethylated CpG islands (CGIs) through its CXXC domain. TET1-FL specifically accumulates 5-hydroxymethylcytosine at the edges of hypomethylated CGIs, while knockdown of endogenous TET1 induces methylation spreading from methylated edges into hypomethylated CGIs. We also found that gene expression changes after TET1-FL overexpression are relatively small and independent of its dioxygenase function. Thus, our results identify TET1 as a maintenance DNA demethylase that does not purposely decrease methylation levels, but specifically prevents aberrant methylation spreading into CGIs in differentiated cells.

[Effects of amygdala kindled seizures on memory retention of passive-avoidance test in rats].

OBJECTIVE: To investigate the effects of amygdala kindled seizures on memory retention of passive-avoidance test in rats. METHODS: Chronic kindled seizures were achieved by daily application of electric stimulations on amygdala until the occurrence of 3 consecutive convulsive seizures. Then a passive-avoidance test was performed to measure memory retention ability in rats; another group of rats received an electric stimulation on amygdala 5 min before the training trail to observe the effects of acute seizure attack on memory retention ability. RESULT: In the training trail and the 1st day of the test trail, there was no difference in the latency to enter dark compartment between chronic kindled seizure group and its corresponding control group. However, the latency significantly increased at the 5 th day of test trail. In addition, the latency of acute seizure attack group rats significantly decreased at the 1 st day and 5 th day of test trail. CONCLUSION: Chronic amygdala kindled seizures increase memory retention of passive-avoidance test in rats, and acute seizure attack impairs this action.

Low-frequency stimulation of the tuberomammillary nucleus facilitates electrical amygdaloid-kindling acquisition in Sprague-Dawley rats.

Histamine plays a suppressive role in seizure. The tuberomammillary nucleus (TM) is the only locus of histaminergic neurons in the brain. To determine whether deep brain stimulation (DBS) of the TM provides protection against seizures, we tested the effects of low-frequency stimulation (LFS, 1 Hz), high frequency stimulation (HFS, 100 Hz), and electrolytic lesions of the TM on seizures generated by amygdaloid kindling, pentylenetetrazol (PTZ) and maximal electroshock (MES) in rats. LFS of TM accelerated the progression of behavioral seizure stage and increased the mean afterdischarge duration (ADD) during acquisition of amygdaloid-kindling seizures, but had no considerable anticonvulsive effect in fully kindled animals. It augmented the MES-induced seizures as well, but had no appreciable effects on PTZ-kindled seizures. In addition, both HFS and bilateral lesions of the TM exacerbated the progression of amygdaloid-kindling seizures. These results suggest that specific negative sites for DBS exist in the brain, such as the TM. This study indicates that it is crucial to choose a suitable target for DBS in the clinical treatment of epilepsy.

[Involvement of endogenous histamine in modulatory effect of morphine on seizure susceptibility in mice].

OBJECTIVE: To investigate the modulatory effects of morphine on the susceptibility to pentylenetetrazole-induced seizures, and the involvement of endogenous histamine in this process. METHODS: Both the wild-type (WT) mice and histidine decarboxylase (a key enzyme for histamine biosynthesis) deficient (HDC-KO) mice were subcutaneously injected with different doses of morphine, and 1 hour later the pentylenetetrazole solution (1.5 %) was infused into the tail vein at a constant rate of 0.3 ml/min. The minimal dose of pentylenetetrazole (mg/kg) needed to induce myoclonic jerks and clonus convulsion was recorded as the thresholds of seizures. RESULT: In WT mice, morphine dose-dependently decreased the thresholds of both myoclonic jerks and clonus convulsion. In HDC-KO mice, morphine at 10 mg/kg only significantly decreased the threshold of myoclonic jerks from (38.6 +/-2.9)mg/kg to (32.5 +/-0.7)mg/kg, but had no significant effect on the threshold of clonus convulsion [from (51.8 +/-2.1)mg/kg to (47.6 +/-1.2)mg/kg]. In addition, the value of decreased myoclonic jerks (15.8 +/-1.4)% and clonus convulsion (8.3 +/-0.9)% thresholds were much lower in HDC-KO mice than in WT mice [(26.1 +/-2.5)% and (20.8 +/-2.4)%, respectively]. CONCLUSION: Morphine can decrease the thresholds of pentylenetetrazole in induction of seizure, and the endogenous histamine may be involved in this process.

Lesion of the tuberomammillary nucleus E2-region attenuates postictal seizure protection in rats.

Postictal seizure protection (PSP) is an endogenous anticonvulsant phenomenon that follows an epileptic seizure and inhibits the induction of further seizures. The tuberomammillary nucleus (TM), located in the posterior hypothalamus, consists of five subregions and is the sole source of histaminergic neurons in the brain. To determine whether the TM is involved in PSP in rats, we tested the effects of bilateral electrolytic lesions of the TM E2-region on seizures induced by intermittent maximal electroshock (MES). The TM E2-region lesions significantly attenuated PSP during the intermittent MES procedure. Furthermore, intracerebroventricular injection of alpha-fluoromethylhistidine (100 microg), a selective and irreversible histidine decarboxylase inhibitor, mimicked the attenuation of PSP induced by the lesion of TM E2-region. In addition, neurochemical experiments revealed that the TM E2-region lesions markedly decreased basal histamine levels in the cortex, hippocampus, brainstem and hypothalamus, but had no significant effect on basal glutamate and GABA levels. Moreover, intermittent MES induced a persistent decrease of brain histamine levels in both sham-operated and lesioned rats. These results indicate that through its intrinsic histaminergic system, the TM may exert powerful inhibitory function during the intermittent MES procedure and actively participate in the mechanisms of PSP.