DNA repair protein DNA-PK protects PC12 cells from oxidative stress-induced apoptosis involving AKT phosphorylation

Background

Emerging evidence suggest that DNA-PK complex plays a role in the cellular response to oxidative stress, in addition to its function of double strand break (DSB) repair. In this study we evaluated whether DNA-PK participates in oxidative stress response and whether this role is independent of its function in DNA repair.

Methods and results

We used a model of H₂O₂-induced DNA damage in PC12 cells (rat pheochromocytoma), a well-known neuronal tumor cell line. We found that H₂O₂ treatment of PC12 cells induces an increase in DNA-PK protein complex levels, along with an elevation of DNA damage, measured both by the formation of γΗ2ΑX foci, detected by immunofluorescence, and γH2AX levels detected by western blot analysis. After 24 h of cell recovery, γΗ2ΑX foci are repaired both in the absence and presence of DNA-PK kinase inhibitor NU7026, while an increase of apoptotic cells is observed when DNA-PK activity is inhibited, as revealed by counting pycnotic nuclei and confirmed by FACS analysis. Our results suggest a role of DNA-PK as an anti-apoptotic factor in proliferating PC12 cells under oxidative stress conditions. The anti-apoptotic role of DNA-PK is associated with AKT phosphorylation in Ser473. On the contrary, in differentiated PC12 cells, were the main pathway to repair DSBs is DNA-PK-mediated, the inhibition of DNA-PK activity causes an accumulation of DNA damage.

Conclusions

Taken together, our results show that DNA-PK can protect cells from oxidative stress induced-apoptosis independently from its function of DSB repair enzyme.

Graphical Abstract

Direct Reprogramming of Somatic Cells to Neurons: Pros and Cons of Chemical Approach

Translating successful preclinical research in neurodegenerative diseases into clinical practice has been difficult. The preclinical disease models used for testing new drugs not always appear predictive of the effects of the agents in the human disease state. Human induced pluripotent stem cells, obtained by reprogramming of adult somatic cells, represent a powerful system to study the molecular mechanisms of the disease onset and pathogenesis. However, these cells require a long time to differentiate into functional neural cells and the resetting of epigenetic information during reprogramming, might miss the information imparted by age. On the contrary, the direct conversion of somatic cells to neuronal cells is much faster and more efficient, it is safer for cell therapy and allows to preserve the signatures of donors’ age. Direct reprogramming can be induced by lineage-specific transcription factors or chemical cocktails and represents a powerful tool for modeling neurological diseases and for regenerative medicine. In this Commentary we present and discuss strength and weakness of several strategies for the direct cellular reprogramming from somatic cells to generate human brain cells which maintain age‐related features. In particular, we describe and discuss chemical strategy for cellular reprogramming as it represents a valuable tool for many applications such as aged brain modeling, drug screening and personalized medicine.

Nicotine Changes Airway Epithelial Phenotype and May Increase the SARS-COV-2 Infection Severity

(1) Background: Nicotine is implicated in the SARS-COV-2 infection through activation of the α7-nAChR and over-expression of ACE2. Our objective was to clarify the role of nicotine in SARS-CoV-2 infection exploring its molecular and cellular activity. (2) Methods: HBEpC or si-mRNA-α7-HBEpC were treated for 1 h, 48 h or continuously with 10-7 M nicotine, a concentration mimicking human exposure to a cigarette. Cell viability and proliferation were evaluated by trypan blue dye exclusion and cell counting, migration by cell migration assay, senescence by SA-β-Gal activity, and anchorage-independent growth by cloning in soft agar. Expression of Ki67, p53/phospho-p53, VEGF, EGFR/pEGFR, phospho-p38, intracellular Ca2+, ATP and EMT were evaluated by ELISA and/or Western blotting. (3) Results: nicotine induced through α7-nAChR (i) increase in cell viability, (ii) cell proliferation, (iii) Ki67 over-expression, (iv) phospho-p38 up-regulation, (v) EGFR/pEGFR over-expression, (vi) increase in basal Ca2+ concentration, (vii) reduction of ATP production, (viii) decreased level of p53/phospho-p53, (ix) delayed senescence, (x) VEGF increase, (xi) EMT and consequent (xii) enhanced migration, and (xiii) ability to grow independently of the substrate. (4) Conclusions: Based on our results and on evidence showing that nicotine potentiates viral infection, it is likely that nicotine is involved in SARS-CoV-2 infection and severity.

Amyloid-β Oligomers-induced Mitochondrial DNA Repair Impairment Contributes to Altered Human Neural Stem Cell Differentiation

BACKGROUND

Amyloid-β42 oligomers (Aβ42O), the proximate effectors of neurotoxicity observed in Alzheimer's disease (AD), can induce mitochondrial oxidative stress and impair mitochondrial function besides causing mitochondrial DNA (mtDNA) damage. Aβ42O also regulate the proliferative and differentiative properties of stem cells.

OBJECTIVE

We aimed to study whether Aβ42O-induced mtDNA damage is involved in the regulation of stem cell differentiation.

METHOD

Human iPSCs-derived neural stem cell (NSC) was applied to investigate the effect of Aβ42O on reactive oxygen species (ROS) production and DNA damage using mitoSOX staining and long-range PCR lesion assay, respectively. mtDNA repair activity was measured by non-homologous end joining (NHEJ) in vitro assay using mitochondria isolates and the expression and localization of NHEJ components were determined by Western blot and immunofluorescence assay. The expressions of Tuj-1 and GFAP, detected by immunofluorescence and qPCR, respectively, were examined as an index of neurons and astrocytes production.

RESULTS

We show that in NSC Aβ42O treatment induces ROS production and mtDNA damage and impairs DNA end joining activity. NHEJ components, such as Ku70/80, DNA-PKcs, and XRCC4, are localized in mitochondria and silencing of XRCC4 significantly exacerbates the effect of Aβ42O on mtDNA integrity. On the contrary, pre-treatment with Phytic Acid (IP6), which specifically stimulates DNA-PK-dependent end-joining, inhibits Aβ42O-induced mtDNA damage and neuronal differentiation alteration.

CONCLUSION

Aβ42O-induced mtDNA repair impairment may change cell fate thus shifting human NSC differentiation toward an astrocytic lineage. Repair stimulation counteracts Aβ42O neurotoxicity, suggesting mtDNA repair pathway as a potential target for the treatment of neurodegenerative disorders like AD.

The analysis of glutamate and glutamine frequencies in human proteins as marker of tissue oxygenation

In this study, we investigated whether the relative abundance of glutamate and glutamine in human proteins reflects the availability of these amino acids (AAs) dictated by the cellular context. In particular, because hypoxia increases the conversion of glutamate to glutamine, we hypothesized that the ratio glutamate/glutamine could be related to tissue oxygenation. By histological, biochemical and genetic evaluation, we identified proteins expressed selectively by distinct cellular populations that are exposed in the same tissue to high or low oxygenation, or proteins codified by different chromosomal loci. Our biochemical assessment was implemented by software tools that calculated the absolute and the relative frequencies of all AAs contained in the proteins. Moreover, an agglomerative hierarchical cluster analysis was performed. In the skin model that has a strictly local metabolism, we demonstrated that the ratio glutamate/glutamine of the selected proteins was directly proportional to oxygenation. Accordingly, the proteins codified by the epidermal differentiation complex in the region 1q21.3 and by the lipase clustering region 10q23.31 showed a significantly lower ratio glutamate/glutamine compared with the nearby regions of the same chromosome. Overall, our results demonstrate that the estimation of glutamate/glutamine ratio can give information on tissue oxygenation and could be exploited as marker of hypoxia, a condition common to several pathologies.

Impact of different stages of intrauterine inflammation on outcome of preterm neonates: Gestational age-dependent and -independent effect

Objective

To investigate the impact of different stages of intrauterine inflammation (IUI) on neonatal outcomes, before and after adjusting for gestational age (GA) and other perinatal confounders.

Methods

This was an observational, prospective, single-center cohort study including all eligible neonates with GA < 35 weeks and/or birth weight ≤ 1500 g born at a 3^rd level Neonatal Intensive Care Unit between 2011 and 2014. Pathological patterns of placenta, membranes and cord were classified according to Redline’s criteria. Multivariable linear and logistic regression models were applied, either including or not GA among the covariates.

Results

Of the 807 enrolled neonates, 134 (16.6%) had signs of IUI: among these, 54.5% showed just histological chorioamnionitis (HCA), 25.4% had HCA + funisitis (FUN) stage 1, and 20.1% had HCA + FUN stage 2–3. At univariate analysis, HCA increased the risk for retinopathy of prematurity (ROP) and bronchopulmonary dysplasia, while FUN (any stage) had a deleterious impact on all outcomes investigated. After adjustment for covariates not including GA, HCA was a risk factor only for ROP (OR = 2.8, CI: 1–7.8), while FUN (any stage) was still associated with increased ORs for all outcomes (p <0.01). Upon inclusion of GA in the regression model, the results differed remarkably. HCA was associated with lower risk for mechanical ventilation (OR = 0.3, CI: 0.1–0.7) and need for surfactant (OR = 0.5, CI: 0.2–0.9), while FUN (any stage) worsened clinical conditions at birth (p <0.05), increased the risk for early-onset sepsis (p <0.01), and increased the length of mechanical ventilation (FUN stage 2–3 only, RC = 6.5 days, CI: 2–11). No other outcome was affected.

Conclusions

IUI, especially FUN, negatively impact most neonatal morbidities, but its effect is partially reverted adjusting for GA. Considered that GA is an intermediate variable interposed between prenatal causes of prematurity and outcomes, the appropriateness of adjusting for GA may be questionable.

Monitoring cognitive change in multiple sclerosis using a computerized cognitive battery

Background

Cognitive monitoring that can detect short-term change in multiple sclerosis is challenging. Computerized cognitive batteries such as the CogState Brief Battery can rapidly assess commonly affected cognitive domains.

Objectives

The purpose of this study was to establish the acceptability and sensitivity of the CogState Brief Battery in multiple sclerosis patients compared to controls. We compared the sensitivity of the CogState Brief Battery to that of the Paced Auditory Serial Addition Test over 12 months.

Methods

Demographics, Expanded Disability Status Scale scores, depression and anxiety scores were compared with CogState Brief Battery and Paced Auditory Serial Addition Test performances of 51 patients with relapsing-remitting multiple sclerosis, 19 with secondary progressive multiple sclerosis and 40 healthy controls. Longitudinal data in 37 relapsing-remitting multiple sclerosis patients were evaluated using linear mixed models.

Results

Both the CogState Brief Battery and the Paced Auditory Serial Addition Test discriminated between multiple sclerosis and healthy controls at baseline (p<0.001). CogState Brief Battery tasks were more acceptable and caused less anxiety than the Paced Auditory Serial Addition Test (p<0.001). In relapsing-remitting multiple sclerosis patients, reaction time slowed over 12 months (p<0.001) for the CogState Brief Battery Detection (mean change -34.23 ms) and Identification (-25.31 ms) tasks. Paced Auditory Serial Addition Test scores did not change over this time.

Conclusions

The CogState Brief Battery is highly acceptable and better able to detect cognitive change than the Paced Auditory Serial Addition Test. The CogState Brief Battery could potentially be used as a practical cognitive monitoring tool in the multiple sclerosis clinic setting.

Epithelial Neoplasia of the Endometrium in Pregnancy. A Case Report

A case of focal severe atypical hyperplasia-carcinoma in situ discovered during voluntary abortion is described. The patient did not undergo hysterectomy; after abortion, menses were regular and the endometrium was histologically normal at a control. Ten cases of endometrial epithelial neoplasia in pregnancy (9 cases) or in puerperium (1 case) found in the literature were reviewed. Although in some of them stromal invasion, which actually is the main prognostic indicator of endometrial neoplasia, was absent or not documented, all lesions were designated as adenocarcinoma. There is evidence that young women with a noninvasive neoplasm and desiring children or preservation of the uterus may be treated conservatively even if the lesion is detected in pregnancy or puerperium.

Acute myeloid leukemia and pregnancy: clinical experience from a single center and a review of the literature

BACKGROUND

Acute myeloid leukemia (AML) accounts for more than two thirds of leukemia during pregnancy and has an incidence of 1 in 75,000 to 100,000. Its clinical management remains a challenging therapeutic task both for patient and medical team, given to the therapy-attributable risks for mother and fetus and the connected counseling regarding pregnancy continuation.

METHODS

We provided a review of updated literature and a comprehensive description of five maternal/fetal outcomes of AML cases diagnosed concomitantly to pregnancy and treated at our Institution from 2006 to 2012.

RESULTS

Median age at AML diagnosis was 32 years (31-39). One diagnosis was performed in first trimester and the patient asked for therapeutic abortion before starting chemotherapy. Three cases were diagnosed in second/third trimester; in one case leukemia was diagnosed concomitantly with intrauterine fetal death, while the remaining two patients continued pregnancy and delivered a healthy baby by cesarean section. In only one of these two cases chemotherapy was performed during pregnancy (at 24 + 5 weeks) and consisted of a combination of daunorubicine and cytarabine. Therapy was well tolerated and daily fetus monitoring was performed. After completion of 30 weeks of gestation a cesarean section was carried out; the newborn had an Apgar score of 5/1'-7/5'-9/10', oxygen therapy was temporarily given and peripheral counts displayed transient mild leukopenia. One patient had diagnosis of myelodysplastic syndrome rapidly progressed to AML after delivery. Four out of the 5 described women are currently alive and disease-free. Three children were born and long-term follow-up has shown normal growth and development.

CONCLUSIONS

The treatment of AML occurring during pregnancy is challenging and therapeutic decisions should be taken individually for each patient. Consideration must be given both to the immediate health of mother and fetus and to long-term infant health. Our series confirmed the literature data: fetal toxicity of cytostatic therapy clusters during the first trimester; while chemotherapy can be administered safely during second/third trimester and combination of daunorubicin and cytarabine is recommended for induction.

Herpes Simplex Virus-Type1 (HSV-1) Impairs DNA Repair in Cortical Neurons

Several findings suggest that Herpes simplex virus-1 (HSV-1) infection plays a role in the neurodegenerative processes that characterize Alzheimer’s disease (AD), but the underlying mechanisms have yet to be fully elucidated. Here we show that HSV-1 productive infection in cortical neurons causes the accumulation of DNA lesions that include both single (SSBs) and double strand breaks (DSBs), which are reported to be implicated in the neuronal loss observed in neurodegenerative diseases. We demonstrate that HSV-1 downregulates the expression level of Ku80, one of the main components of non-homologous end joining (NHEJ), a major pathway for the repair of DSBs. We also provide data suggesting that HSV-1 drives Ku80 for proteasomal degradation and impairs NHEJ activity, leading to DSB accumulation. Since HSV-1 usually causes life-long recurrent infections, it is possible to speculate that cumulating damages, including those occurring on DNA, may contribute to virus induced neurotoxicity and neurodegeneration, further suggesting HSV-1 as a risk factor for neurodegenerative conditions.

Biochemical characterization of sirtuin 6 in the brain and its involvement in oxidative stress response

Sirtuin 6 (SIRT6) is a member of nicotinamide adenine dinucleotide-dependent deacetylase protein family and has been implicated in the control of glucose and lipid metabolism, cancer, genomic stability and DNA repair. Moreover, SIRT6 regulates the expression of a large number of genes involved in stress response and aging. The role of SIRT6 in brain function and neuronal survival is largely unknown. Here, we biochemically characterized SIRT6 in brain tissues and primary neuronal cultures and found that it is highly expressed in cortical and hippocampal regions and enriched in the synaptosomal membrane fraction. Immunoblotting analysis on cortical and hippocampal neurons showed that SIRT6 is downregulated during maturation in vitro, reaching the lowest expression at 11 days in vitro. In addition, SIRT6 overexpression in terminally differentiated cortical and hippocampal neurons, mediated by a neuron-specific recombinant adeno-associated virus, downregulated cell viability under oxidative stress condition. By contrast, under control condition, SIRT6 overexpression had no detrimental effect. Overall these results suggest that SIRT6 may play a role in synaptic function and neuronal maturation and it may be implicated in the regulation of neuronal survival.

Systematic review of randomised clinical trials on topical ciclosporin A for the treatment of dry eye disease

AIMS

Topical ciclosporin A (CsA) is a therapeutic option for dry eye disease (DED) to control ocular surface inflammation and improve tear function. The aim of this study is to systematically review data from randomised clinical trials (RCTs) evaluating efficacy and safety of topical CsA treatment for DED.

METHODS

Articles published up to December 2012 were identified from Medline, Embase and the Cochrane Controlled Trials Register. A total of 18 RCTs that evaluated the efficacy and safety of different topical CsA formulations for the treatment of DED were selected according to the set criteria. The Jadad score was calculated to assess RCT quality.

RESULTS

The mean Jadad score of the included RCTs was 2.8±0.6. All CsA formulations proved safe for the treatment of DED. Symptoms improved in 100% (9/9) RCTs, tear function improved in 72% (13/18) RCTs and ocular surface damage was ameliorated in 53% (9/17) RCTs in patients with DED. No improvements with CsA treatment versus control were observed in DED resulting from surgical procedures, contact lens use and thyroid orbitopathy. Statistical comparison of CsA efficacy through a meta-analysis of data was not possible due to a lack of standardised criteria and comparable outcomes among studies.

CONCLUSIONS

Although topical CsA appears to be a safe treatment for DED, evidence emerging from RCTs is limited, and this affects the strength of recommendations to healthcare providers and policymakers for optimal management. Standardised diagnostic criteria to assess the efficacy of topical CsA are recommended to improve the design of future RCTs in DED.

Sublethal doses of β-amyloid peptide abrogate DNA-dependent protein kinase activity

Accumulation of DNA damage and deficiency in DNA repair potentially contribute to the progressive neuronal loss in neurodegenerative disorders, including Alzheimer disease (AD). In multicellular eukaryotes, double strand breaks (DSBs), the most lethal form of DNA damage, are mainly repaired by the nonhomologous end joining pathway, which relies on DNA-PK complex activity. Both the presence of DSBs and a decreased end joining activity have been reported in AD brains, but the molecular player causing DNA repair dysfunction is still undetermined. β-Amyloid (Aβ), a potential proximate effector of neurotoxicity in AD, might exert cytotoxic effects by reactive oxygen species generation and oxidative stress induction, which may then cause DNA damage. Here, we show that in PC12 cells sublethal concentrations of aggregated Aβ(25-35) inhibit DNA-PK kinase activity, compromising DSB repair and sensitizing cells to nonlethal oxidative injury. The inhibition of DNA-PK activity is associated with down-regulation of the catalytic subunit DNA-PK (DNA-PKcs) protein levels, caused by oxidative stress and reversed by antioxidant treatment. Moreover, we show that sublethal doses of Aβ(1-42) oligomers enter the nucleus of PC12 cells, accumulate as insoluble oligomeric species, and reduce DNA-PK kinase activity, although in the absence of oxidative stress. Overall, these findings suggest that Aβ mediates inhibition of the DNA-PK-dependent nonhomologous end joining pathway contributing to the accumulation of DSBs that, if not efficiently repaired, may lead to the neuronal loss observed in AD.

Glutamatergic neurotransmission in a mouse model of Niemann-Pick type C disease

Niemann-Pick Type C Disease (NPCD) is a progressive neurodegenerative disorder characterized by accumulation of free cholesterol, sphingomyelin, glycosphingolipids (GSLs) and sphingosine in lysosomes, mainly due to a mutation in the NPC1 gene. One of the main symptoms in NPCD patients is hyperexcitability leading to epileptic activity, however, the pathophysiological basis of this neural disorder is not yet well understood. Here we studied the excitatory neurotransmission in the hippocampus of BALB/c NPC1NIH (NPC1-/-) mice, a well-described animal model of the disease. We report that hippocampal field potential population spike (fPS), as well as paired pulse ratio, is enhanced in NPC1-/- with respect to Wild Type (WT). To evaluate the contribution of glutamate receptor activity in the enhanced fPS observed in mutant mice, we recorded slices treated with glutamate receptor agonists alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) and Kainate (KA). We found that a prolonged application of KA and AMPA in NPC1-/- mice do not induce the dramatic decrease of synaptic transmission observed in WT hippocampal slices suggesting a functional impairment of presynaptic KA receptors and an imbalance of AMPA receptor exo/endocytosis. In line with electrophysiological data, we also found notable differences in calcium influx during KA and AMPA bath application in NPC1-/- hippocampal culture as compared with WT. Nevertheless in synaptosomal membranes, Western Blot analysis didn't reveal any modification in protein expression levels of KA and AMPA receptor subunits. All together these data indicate that in mutant mice the hyperexcitability, that is at the basis of the insurgence of seizures, might be due to the enhanced glutamatergic neurotransmission caused by an altered KA and AMPA receptor functioning.

Thymosin beta4 targeting impairs tumorigenic activity of colon cancer stem cells

Thymosin β4 (Tβ4) is an actin-binding peptide overexpressed in several tumors, including colon carcinomas. The aim of this study was to investigate the role of Tβ4 in promoting the tumorigenic properties of colorectal cancer stem cells (CR-CSCs), which are responsible for tumor initiation and growth. We first found that CR-CSCs from different patients have higher Tβ4 levels than normal epithelial cells. Then, we used a lentiviral strategy to down-regulate Tβ4 expression in CR-CSCs and analyzed the effects of such modulation on proliferation, survival, and tumorigenic activity of CR-CSCs. Empty vector-transduced CR-CSCs were used as a control. Targeting of the Tβ4 produced CR-CSCs with a lower capacity to grow and migrate in culture and, interestingly, reduced tumor size and aggressiveness of CR-CSC-based xenografts in mice. Moreover, such loss in tumorigenic activity was accompanied by a significant increase of phosphatase and tensin homologue (PTEN) and a concomitant reduction of the integrin-linked kinase (ILK) expression, which resulted in a decreased activation of protein kinase B (Akt). Accordingly, exogenous expression of an active form of Akt rescued all the protumoral features lost after Tβ4 targeting in CR-CSCs. In conclusion, Tβ4 may have important implications for therapeutic intervention for treatment of human colon carcinoma.

Downregulation of thymosin beta4 in neural progenitor grafts promotes spinal cord regeneration

Thymosin beta4 (Tbeta4) is an actin-binding peptide whose expression in developing brain correlates with migration and neurite extension of neurons. Here, we studied the effects of the downregulation of Tbeta4 expression on growth and differentiation of murine neural progenitor cells (NPCs), using an antisense lentiviral vector. In differentiation-promoting medium, we found twice the number of neurons derived from the Tbeta4-antisense-transduced NPCs, which showed enhanced neurite outgrowth accompanied by increased expression of the adhesion complex N-cadherin-beta-catenin and increased ERK activation. Importantly, when the Tbeta4-antisense-transduced NPCs were transplanted in vivo into a mouse model of spinal cord injury, they promoted a significantly greater functional recovery. Locomotory recovery correlated with increased expression of the regeneration-promoting cell adhesion molecule L1 by the grafted Tbeta4-antisense-transduced NPCs. This resulted in an increased number of regenerating axons and in sprouting of serotonergic fibers surrounding and contacting the Tbeta4-antisense-transduced NPCs grafted into the lesion site. In conclusion, our data identify a new role for Tbeta4 in neuronal differentiation of NPCs by regulating fate determination and process outgrowth. Moreover, NPCs with reduced Tbeta4 levels generate an L1-enriched environment in the lesioned spinal cord that favors growth and sprouting of spared host axons and enhances the endogenous tissue-repair processes.

Mutation of SHOC2 promotes aberrant protein N-myristoylation and causes Noonan-like syndrome with loose anagen hair

N-myristoylation is a common form of co-translational protein fatty acylation resulting from the attachment of myristate to a required N-terminal glycine residue. We show that aberrantly acquired N-myristoylation of SHOC2, a leucine-rich repeat-containing protein that positively modulates RAS-MAPK signal flow, underlies a clinically distinctive condition of the neuro-cardio-facial-cutaneous disorders family. Twenty-five subjects with a relatively consistent phenotype previously termed Noonan-like syndrome with loose anagen hair (MIM607721) shared the 4A>G missense change in SHOC2 (producing an S2G amino acid substitution) that introduces an N-myristoylation site, resulting in aberrant targeting of SHOC2 to the plasma membrane and impaired translocation to the nucleus upon growth factor stimulation. Expression of SHOC2(S2G) in vitro enhanced MAPK activation in a cell type-specific fashion. Induction of SHOC2(S2G) in Caenorhabditis elegans engendered protruding vulva, a neomorphic phenotype previously associated with aberrant signaling. These results document the first example of an acquired N-terminal lipid modification of a protein causing human disease.

GAB(A) receptors present higher affinity and modified subunit composition in spinal motor neurons from a genetic model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disease characterized by the selective degeneration of motor neurons in the spinal cord, brainstem and cerebral cortex. In this study we have analysed the electrophysiological properties of GABA(A) receptors and GABA(A) alpha1 and alpha2 subunits expression in spinal motor neurons in culture obtained from a genetic model of ALS (G93A) and compared with transgenic wild type SOD1 (SOD1) and their corresponding non transgenic litter mates (Control). Although excitotoxic motor neuron death has been extensively studied in relation to Ca(2+)-dependent processes, strong evidence indicates that excitotoxic cell death is also remarkably dependent on Cl(-) ions and on GABA(A) receptor activation. In this study we have analysed the electrophysiological properties of GABA(A) receptors and the expression of GABA(A)alpha(1) and alpha(2) subunits in cultured motor neurons obtained from a genetic model of amyotrophic lateral sclerosis (G93A) and compared them with transgenic wild-type Cu,Zn superoxide dismutase and their corresponding non-transgenic littermates (Control). In all tested motor neurons, the application of gamma-aminobutyric acid (GABA) (0.5-100 mum) evoked an inward current that was reversibly blocked by bicuculline (100 mum), thus indicating that it was mediated by the activation of GABA(A) receptors. Our results indicate that the current density at high GABA concentrations is similar in control, Cu,Zn superoxide dismutase and G93A motor neurons. However, the dose-response curve significantly shifted toward lower concentration values in G93A motor neurons and the extent of desensitization also increased in these neurons. Finally, multiplex single-cell real-time polymerase chain reaction and immunofluorescence revealed that the amount of GABA(A)alpha(1) subunit was significantly increased in G93A motor neurons, whereas the levels of alpha(2) subunit were unchanged. These data show that the functionality and expression of GABA(A) receptors are altered in G93A motor neurons inducing a higher Cl(-) influx into the cell with a possible consequent neuronal excitotoxicity acceleration.

Neuroprotective effects of thymosin beta4 in experimental models of excitotoxicity

The aim of this study was to evaluate the possible neuroprotective effects of thymosin beta(4) in different models of excitotoxicity. The application of thymosin beta(4) significantly attenuated glutamate-induced toxicity both in primary cultures of cortical neurons and in rat hippocampal slices. In in vivo experiments, the intracerebroventricular administration of thymosin beta(4) significantly reduced hippocampal neuronal loss induced by kainic acid. These results show that thymosin beta(4) induced a protective effect in models of excitotoxicity. The mechanisms underlying such an effect, as well as the real neuroprotective potential of thymosin beta(4), are worthy of further investigations.

Reduced GABAB receptor subunit expression and paired-pulse depression in a genetic model of absence seizures

Neocortical networks play a major role in the genesis of generalized spike-and-wave (SW) discharges associated with absence seizures in humans and in animal models, including genetically predisposed WAG/Rij rats. Here, we tested the hypothesis that alterations in GABA(B) receptors contribute to neocortical hyperexcitability in these animals. By using Real-Time PCR we found that mRNA levels for most GABA(B(1)) subunits are diminished in epileptic WAG/Rij neocortex as compared with age-matched non-epileptic controls (NEC), whereas GABA(B(2)) mRNA is unchanged. Next, we investigated the cellular distribution of GABA(B(1)) and GABA(B(2)) subunits by confocal microscopy and discovered that GABA(B(1)) subunits fail to localize in the distal dendrites of WAG/Rij neocortical pyramidal cells. Intracellular recordings from neocortical cells in an in vitro slice preparation demonstrated reduced paired-pulse depression of pharmacologically isolated excitatory and inhibitory responses in epileptic WAG/Rij rats as compared with NECs; moreover, paired-pulse depression in NEC slices was diminished by a GABA(B) receptor antagonist to a greater extent than in WAG/Rij rats further suggesting GABA(B) receptor dysfunction. In conclusion, our data identify changes in GABA(B) receptor subunit expression and distribution along with decreased paired-pulse depression in epileptic WAG/Rij rat neocortex. We propose that these alterations may contribute to neocortical hyperexcitability and thus to SW generation in absence epilepsy.

The synapsin domain E accelerates the exoendocytotic cycle of synaptic vesicles in cerebellar Purkinje cells

Synapsins are synaptic-vesicle-associated phosphoproteins implicated in the regulation of neurotransmitter release and excitability of neuronal networks. Mutation of synapsin genes in mouse and human causes epilepsy. To understand the role of the highly conserved synapsin domain E in the dynamics of release from mammalian inhibitory neurons, we generated mice that selectively overexpress the most conserved part of this domain in cerebellar Purkinje cells. At Purkinje-cell-nuclear-neuron synapses, transgenic mice were more resistant to depression induced by short or prolonged high-frequency stimulations. The increased synaptic performance was accompanied by accelerated release kinetics and shorter synaptic delay. Despite a marked decrease in the total number of synaptic vesicles, vesicles at the active zone were preserved or slightly increased. The data indicate that synapsin domain E increases synaptic efficiency by accelerating both the kinetics of exocytosis and the rate of synaptic vesicle cycling and decreasing depression at the inhibitory Purkinje-cell-nuclear-neuron synapse. These effects may increase the sensitivity of postsynaptic neurons to inhibition and thereby contribute to the inhibitory control of network activity.

Subiculum network excitability is increased in a rodent model of temporal lobe epilepsy

In this study, we used in vitro electrophysiology along with immunohistochemistry and molecular techniques to study the subiculum--a limbic structure that gates the information flow from and to the hippocampus--in pilocarpine-treated epileptic rats. Comparative data were obtained from age-matched nonepileptic controls (NEC). Subicular neurons in hippocampal-entorhinal cortex (EC) slices of epileptic rats were: (i) hyperexcitable when activated by CA1 or EC inputs; and (ii) generated spontaneous postsynaptic potentials at higher frequencies than NEC cells. Analysis of pharmacologically isolated, GABA(A) receptor-mediated inhibitory postsynaptic potentials revealed more positive reversal potentials in epileptic tissue (-67.8 +/- 6.3 mV, n = 16 vs. -74.8 +/- 3.6 mV in NEC, n = 13; P < 0.001) combined with a reduction in peak conductance (17.6 +/- 11.3 nS vs. 41.1 +/- 26.7 nS in NEC; P < 0.003). These electrophysiological data correlated in the epileptic subiculum with (i) reduced levels of mRNA expression and immunoreactivity of the neuron-specific potassium-chloride cotransporter 2; (ii) decreased number of parvalbumin-positive cells; and (iii) increased synaptophysin (a putative marker of sprouting) immunoreactivity. These findings identify an increase in network excitability within the subiculum of pilocarpine-treated, epileptic rats and point at a reduction in inhibition as an underlying mechanism.

Molecular basis for keratoconus: lack of TrkA expression and its transcriptional repression by Sp3

Keratoconus is the most common corneal dystrophy that leads to severe visual impairment. Although the major etiological factors are genetic, the pathogenetic mechanism(s) is unknown. No medical treatments exist, and the only therapeutic approach is corneal transplantation. Recent data demonstrate the involvement of nerve growth factor (NGF) in trophism and corneal wound healing. In this study, we investigated alterations in the NGF pathway in keratoconus-affected corneas and found a total absence of the NGF-receptor TrkA (TrkA(NGFR)) expression and a decreased expression of NGF and p75(NTR). The absence of TrkA(NGFR) expression was associated with a strong increase in the Sp3 repressor short isoform(s) and a lack of the Sp3 activator long isoform. Sp3 is a bifunctional transcription factor that has been reported to stimulate or repress the transcription of numerous genes. Indeed, we found that Sp3 short isoform(s) overexpression in cell culture results in a down-regulation of TrkA(NGFR) expression. We suggest that an imbalance in Sp transcription-factor isoforms may play a role in controlling the NGF signaling, thus contributing to the pathogenesis of keratoconus. This mechanism for the transcriptional repression of the TrkA(NGFR) gene can provide the platform for the development of a therapeutic strategy.

Clinical and cytological findings in limbal stem cell deficiency

PURPOSE

To evaluate and relate the clinical (including corneal sensitivity and tear function) and cytological (presence of goblet cells and cytokeratin 3- and 19-positive cells) features of limbal stem cell deficiency (LSCD).

METHODS

Twenty-nine patients (44 eyes) with a clinical diagnosis of LSCD participated in this study. Corneal signs (epithelial alterations, superficial neovascularisation and stromal scarring) and cytological findings (presence of goblet cells and cytokeratins 3 and 19) were evaluated and scored (from 0 to 3) from each of the five corneal sectors. Corneal sensitivity (Cochet-Bonnet aesthesiometer) and tear function (Schirmer test and BUT) were also assessed. Cytological scores were correlated statistically with both corneal signs and sensitivity values.

RESULTS

Cytokeratin 19-positive cells were found in 82% of corneal impression cytology samples, while goblet cells were identified in only 59% of these same samples. Cytokeratin 3-positive cells were present in 61% of LSCD eyes and in all unaffected eyes. Corneal sensitivity was significantly decreased in affected eyes compared with contralateral, healthy eyes (1.6+/-1.7 cm versus 5.7+/-0.3 cm). Tear function tests did not show significant changes. In LSCD eyes, goblet cells and cytokeratin 19-positive cells on the corneal surface were significantly correlated to corneal epithelial alterations and to corneal superficial neovascularisation (p<0.001). Corneal cytokeratin 3-positive cells were inversely related to epithelial alterations (p=0.003). Corneal sensitivity was decreased in corneal sectors with epithelial alterations (p<0.001), neovascularisation (p<0.001) and stromal abnormalities (p=0.049), and was indirectly related to the presence of goblet cells (p=0.005) and cytokeratin 19-positive cells (p<0.001).

CONCLUSION

This study confirmed the importance of cytological tests in the diagnosis of LSCD. Furthermore, the absence of goblet cells may not exclude corneal conjunctivalisation as demonstrated by cytokeratin 19 immunostaining. Lastly, corneal conjunctivalisation was associated with zone-specific impairment in corneal sensitivity.

Phosphorylation by cAMP-dependent protein kinase is essential for synapsin-induced enhancement of neurotransmitter release in invertebrate neurons

Synapsins are synaptic vesicle-associated phosphoproteins involved in the regulation of neurotransmitter release and synapse formation; they are substrates for multiple protein kinases that phosphorylate them on distinct sites. We have previously found that injection of synapsin into Helix snail neurons cultured under low-release conditions increases the efficiency of neurotransmitter release. In order to investigate the role of phosphorylation in this modulatory action of synapsins, we examined the substrate properties of the snail synapsin orthologue recently cloned in Aplysia (apSyn) for various protein kinases and compared the effects of the intracellular injection of wild-type apSyn with those of its phosphorylation site mutants. ApSyn was found to be an excellent in vitro substrate for cAMP-dependent protein kinase, which phosphorylated it at high stoichiometry on a single site (Ser-9) in the highly conserved domain A, unlike the other kinases reported to phosphorylate mammalian synapsins, which phosphorylated apSyn to a much lesser extent. The functional effect of apSyn phosphorylation by cAMP-dependent protein kinase on neurotransmitter release was studied by injecting wild-type or Ser-9 mutated apSyn into the soma of Helix serotonergic C1 neurons cultured under low-release conditions, i.e. in contact with the non-physiological target neuron C3. In this model of impaired neurotransmitter release, the injection of wild-type apSyn induced a significant enhancement of release. This enhancement was virtually absent after injection of the non-phosphorylatable mutant (Ser-9→Ala), but it was maintained after injection of the pseudophosphorylated mutant (Ser-9→Asp). These functional effects of apSyn injection were paralleled by marked ultrastructural changes in the C1 neuron, with the formation of extensive interdigitations of neurite-like processes containing an increased complement of C1 dense core vesicles at the sites of cell-to-cell contact. This structural rearrangement was virtually absent in mock-injected C1 neurons or after injection of the non-phosphorylatable apSyn mutant. These data indicate that phosphorylation of synapsin domain A is essential for the synapsin-induced enhancement of neurotransmitter release and suggest that endogenous kinases phosphorylating this domain play a central role in the regulation of the efficiency of the exocytotic machinery.

4-Aminopyridine-induced epileptogenesis depends on activation of mitogen-activated protein kinase ERK

Extracellular signal-regulated kinases such as ERK1 [p44 mitogen-activated protein kinase (MAPK)] and ERK2 (p42 MAPK) are activated in the CNS under physiological and pathological conditions such as ischemia and epilepsy. Here, we studied the activation state of ERK1/2 in rat hippocampal slices during application of the K(+) channel blocker 4-aminopyridine (4AP, 50 micro m), a procedure that enhances synaptic transmission and leads to the appearance of epileptiform activity. Hippocampal slices superfused with 4AP-containing medium exhibited a marked activation of ERK1/2 phosphorylation that peaked within about 20 min. These effects were not accompanied by changes in the activation state of c-Jun N-terminal kinase (JNK), another member of the MAP kinase superfamily. 4AP-induced ERK1/2 activation was inhibited by the voltage-gated Na(+) channel blocker tetrodotoxin (1 micro m). We also found that application of the ERK pathway inhibitors U0126 (50 micro m) or PD98059 (100 micro m) markedly reduced 4AP-induced epileptiform synchronization, thus abolishing ictal discharges in the CA3 area. The effects induced by U0126 or PD98059 were not associated with changes in the amplitude and latency of the field potentials recorded in the CA3 area following electrical stimuli delivered in the dentate hylus. These data demonstrate that activation of ERK1/2 accompanies the appearance of epileptiform activity induced by 4AP and suggest a cause-effect relationship between the ERK pathway and epileptiform synchronization.

Pseudodoubling of the optic disc: a colour Doppler imaging study

Pseudodoubling of the optic disc is a rare clinical presentation. In these cases it is necessary to exclude retinal coloboma or atrophy following vascular or infectious diseases. We present a case of pseudodoubling of the optic disc in a woman with type 2 diabetes and arterial hypertension. Ophthalmoscopic examination of the fundus showed a disc-like lesion in the right eye and a diabetic retinopathy in the left eye. The lesion was evaluated with fluorescein angiography, neuroradiological and colour Doppler imaging investigations. Colour Doppler imaging confirmed the angiographic findings of anomalous vascularisation of the pseudopapilla and provides an analysis of the choroidal vessel anastomosis between the optic disc and the retinal lesion, revealing that the pseudodoubling in this patient was the result of a chorioretinal coloboma.

Involvement of cholinergic and gabaergic systems in the fragile X knockout mice

Fragile X syndrome is an inherited cause of mental retardation. We used extra- and intracellular recordings in brain slices obtained from wild type and fragile X knockout mice to establish whether bath application of the cholinergic agent carbachol (5 microM) induces different responses in neurons of the subiculum, a limbic structure involved in learning and memory. We found that carbachol diminished excitatory post-synaptic responses induced by CA1 stratum radiatum stimulation in wild type mice, but caused an unexpected increase in knockout animals. Moreover, these responses augmented in knockout mice after carbachol washout, a phenomenon that resembled the muscarinic long-term potentiation seen in wild type mice during application of carbachol and GABA(A) receptor antagonists. We also used paired-pulse stimulation to determine whether the changes in synaptic excitability induced by carbachol were caused by pre- or post-synaptic mechanism. Under control conditions, this protocol induced facilitation in both wild type and knockout mice; in contrast, during carbachol application, this facilitatory effect was seen in wild type mice only. In conclusion, our data highlight for the first time differences in cholinergic and GABA-ergic mechanisms that may contribute to the phenotype of fragile X patients.

Cerebellar granule cell Cre recombinase expression

The cerebellum maintains balance and orientation, refines motor action, stores motor memories, and contributes to the timing aspects of cognition. We generated two mouse lines for making Cre recombinase-mediated gene disruptions largely confined to adult cerebellar granule cells. For this purpose we chose the GABA(A) receptor alpha6 subunit gene, whose expression marks this cell type. Here we describe mouse lines expressing Cre recombinase generated by 1) Cre knocked into the native alpha6 subunit gene by homologous recombination in embryonic stem cells; and 2) Cre recombined into an alpha6 subunit gene carried on a bacterial artificial chromosome (BAC) genomic clone. The fidelity of Cre expression was tested by crossing the mouse lines with the ROSA26 reporter mice. The particular alpha6BAC clone we identified will be valuable for delivering other gene products to cerebellar granule cells.

Human chorionic gonadotropin level as a predictor of trophoblastic infiltration into the tubal wall in ectopic pregnancy: a blinded study

OBJECTIVE

To determine the relationship between gestational age, tubal ultrasonographic diameter, and serum hCG levels and different stages of trophoblastic infiltration of the tubal wall in ectopic pregnancy.

DESIGN

Blinded prospective study.

SETTING

University-based clinic in Italy.

PATIENT(S)

Thirty-seven consecutive patients with an ampullary ectopic pregnancy.

INTERVENTION(S)

Laparoscopic salpingectomy.

MAIN OUTCOME MEASURE(S)

Gestational age, diameter of the tubal mass as determined by transvaginal ultrasonography. and hCG level on the day of surgery. Ectopic pregnancy was classified according to the depth of trophoblastic infiltration: trophoblast limited to the tubal mucosa (stage I), extension to the tubal muscularis (stage II), or complete tubal wall infiltration up to the serosa discontinued by trophoblastic cells (stage III).

RESULT(S)

Fifteen patients (40.5%) had stage I tubal infiltration, 14 (37.8%) had stage II infiltration, and 8 (21.6%) had stage III infiltration. Gestational age and diameter of the tube did not differ among the three groups. The median hCG level was 1,710.5 mIU/mL (range, 113-5,635 mIU/mL) for patients with stage I infiltration. 4,690.0 mIU/mL (range, 150-21,531 mIU/mL) for patients with stage II infiltration, and 15,700.0 mIU/mL (range, 13,809-21,650 mIU/mL) for patients with stage III infiltration. All the patients with hCG levels > 6,000 mIU/mL had stage II or III invasion.

CONCLUSION(S)

These findings may explain why the conservative treatment of ectopic pregnancy is less successful in patients with high hCG levels than in patients with low levels. Use of radical procedures may be justified in the former group.

GABA(A) receptor cell surface number and subunit stability are regulated by the ubiquitin-like protein Plic-1

Controlling the number of functional gamma-aminobutyric acid A (GABA(A)) receptors in neuronal membranes is a crucial factor for the efficacy of inhibitory neurotransmission. Here we describe the direct interaction of GABA(A) receptors with the ubiquitin-like protein Plic-1. Furthermore, Plic-1 is enriched at inhibitory synapses and is associated with subsynaptic membranes. Functionally, Plic-1 facilitates GABA(A) receptor cell surface expression without affecting the rate of receptor internalization. Plic-1 also enhances the stability of intracellular GABA(A) receptor subunits, increasing the number of receptors available for insertion into the plasma membrane. Our study identifies a previously unknown role for Plic-1, a modulation of GABA(A) receptor cell surface number, which suggests that Plic-1 facilitates accumulation of these receptors in dendritic membranes.

Expression of GABA(A) receptor subunits in rat brainstem auditory pathways: cochlear nuclei, superior olivary complex and nucleus of the lateral lemniscus

Inhibition by GABA is important for auditory processing, but any adaptations of the ionotropic type A receptors are unknown. Here we describe, using in situ hybridization, the subunit expression patterns of GABA(A) receptors in the rat cochlear nucleus, superior olivary complex, and dorsal and ventral nuclei of the lateral lemniscus. All neurons express the beta3 and gamma2L subunit messenger RNAs, but use different alpha subunits. In the dorsal cochlear nucleus, fusiform (pyramidal) and giant cells express alpha1, alpha3, beta3 and gamma2L. Dorsal cochlear nucleus interneurons, particularly vertical or tuberculoventral cells and cartwheel cells, express alpha3, beta3 and gamma2L. In the ventral cochlear nucleus, octopus cells express alpha1, beta3, gamma2L and delta. Spherical cells express alpha1, alpha3, alpha5, beta3 and gamma2L. In the superior olivary complex, the expression profile is alpha3, alpha5, beta3 and gamma2L. Both dorsal and ventral cochlear nucleus granule cells express alpha1, alpha6, beta3 and gamma2L; unlike their cerebellar granule cell counterparts, they do not express beta2, gamma2S or the delta subunit genes. The delta subunit's absence from cochlear nucleus granule cells may mean that tonic inhibition mediated by extrasynaptic GABA(A) receptors is less important for this cell type. In both the dorsal and ventral nuclei of the lateral lemniscus, alpha1, beta3 and gamma2L are the main subunit messenger RNAs; the ventral nucleus also expresses the delta subunit. We have mapped, using in situ hybridization, the subunit expression patterns of the GABA(A) receptor in the auditory brainstem nuclei. In contrast to many brain regions, the beta2 subunit gene and gamma2S splice forms are not highly expressed in auditory brainstem nuclei. GABA(A) receptors containing beta3 and gamma2L may be particularly well suited to auditory processing, possibly because of the unique phosphorylation profile of this subunit combination.

Antagonists of P2 receptor prevent NGF-dependent neuritogenesis in PC12 cells

The pheochromocytoma PC12 cell line that develops neuronal characteristics of sympathetic cells after treatment with nerve growth factor (NGF) represents a well-established cellular model system for studying NGF signalling. Interesting information on the different mechanistic pathways of NGF can be obtained by adopting the pharmacological approach of inhibiting P2 receptors, expressed in naive PC12 cells and recognised as important biological mediators of neurotransmitters and growth factors. We show here that Basilen Blue, an antagonist of P2 receptor, reversibly prevents NGF-dependent neurite outgrowth with an IC(50) in the 5-10 microM range. Suramin, oxidised-ATP and diisothiocyanatostilbene-disulfonic acid, differently from other purinoceptor ligands, are also effective in this regard. NGF-dependent regeneration and stability of neurites, selected NGF-dependent extracellular and intracellular protein phosphorylations, binding of [(3)H] ATP to PC12 cell membranes are also modulated by Basilen Blue. On the contrary, cell adhesion, cellular duplication, 5'-nucleotidase activity, NGF-induced tyrosine autophosphorylation of TrkA receptors are not affected. NGF furthermore directly modulates the extracellular release of ATP and especially the levels of P2X(2) receptor protein in PC12 cells. In addition, extracellular ATP improves the neuritogenic effect of sub-optimal concentrations of NGF. Our study identifies P2 receptor ligands, particularly Basilen Blue, as useful tools to dissect different NGF-evoked functions, suggesting a mechanistic role for P2 receptors in the signalling pathways of NGF.

Transvaginal ultrasonography versus uterine needle biopsy in the diagnosis of diffuse adenomyosis

To assess the reliability of transvaginal ultrasonography and uterine needle biopsy, used singly or in combination, in the diagnosis of diffuse adenomyosis, a prospective study with pathological confirmation of the diagnosis was performed. A total of 102 premenopausal women scheduled for hysterectomy because of menorrhagia and/or pelvic pain underwent preoperative transvaginal ultrasonography. After removal of the uterus, a single full-thickness myometrial biopsy specimen was taken from along the median line in the upper third of the posterior uterine wall, using a 14-gauge Trucut needle. Adenomyosis was diagnosed by the sonographer by the presence of indistinctly demarcated heterogeneous myometrial areas with distorted echotexture, and by the pathologist when the distance between the lower border of the endometrium and the affected myometrial area was more than one-half of a low power field. The prevalence of adenomyosis was 28% (29/102 patients). The sensitivity and specificity of transvaginal ultrasonography were 82.7 and 67.1% respectively, compared with 44.8 and 95.9% for uterine needle biopsy. The positive predictive values of the two tests were 50.0 and 81.2% respectively, and the negative predictive values 90.7 and 81.4%, likelihood ratios of a positive test 2.5 and 10.9, likelihood ratios of a negative test 0.3 and 0.6, and kappa indexes of agreement 0.42 and 0.47. Combining the tests did not improve the overall diagnostic performance. Both transvaginal ultrasonography and uterine needle biopsy demonstrated suboptimal test characteristics.

Endometrial ablation with a vaporizing electrode. II. Clinical outcome of a pilot study

BACKGROUND

As a vaporizing electrode has been successfully used to treat submucous myomas, we evaluated its safety and efficacy in performing endometrial ablation.

METHODS

Forty consecutive women with established menorrhagia with (n=26) and without (n=14) submucous myomas were enrolled in a prospective, noncomparative, pilot study. Hysteroscopic endometrial vaporization was performed with pure cutting current set at 200 watts.

RESULTS

All procedures were completed without complications. Median (interquartile range, IQR) fluid deficit was 90 (0-200) ml and median (IQR) operating time 10 (7-12.5) min. A significant correlation was observed between operating time and fluid absorption (Spearman's test by ranks, r=0.47; p=0.002). The degree of difficulty of the operation was classified as none on 28 (70%) occasions, mild on 11 (27.5%) and moderate on one (2.5%). After a mean+/-s.d. follow-up of 20.3+/-2.4 months, amenorrhea or spotting were reported by 23 (57.5%) subjects, hypomenorrhea by 10 (25%), normal flows by six (15%), and menorrhagia by one (2.5%). The median (IQR) menstrual score calculated according to a pictorial blood loss assessment chart dropped from 282.5 (199-383) to 0 (0-15) (p<0.0001). Six (15%) subjects were very satisfied with the effect of surgery, 30 (75%) satisfied, two (5%) uncertain, one (2.5%) dissatisfied and one (2.5%) very dissatisfied.

CONCLUSIONS

The vaporizing electrode seems to combine the benefits of the cutting loop (speed, efficacy and possibility of removing myomas) and the roller-ball electrode (safety and limited fluid absorption) while avoiding their respective disadvantages, and may be considered an interesting alternative in the hysteroscopic treatment of menorrhagia.

Mouse cerebellar granule cell differentiation: electrical activity regulates the GABAA receptor alpha 6 subunit gene

GABAA receptor alpha6 subunit gene expression marks cerebellar granule cell maturation. To study this process, we used the Deltaalpha6lacZ mouse line, which has a lacZ reporter inserted into the alpha6 gene. At early stages of postnatal cerebellar development, alpha6-lacZ expression is mosaic; expression starts at postnatal day 5 in lobules 9 and 10, and alpha6-lacZ is switched on inside-out, appearing first in the deepest postmigratory granule cells. We looked for factors regulating this expression in cell culture. Membrane depolarization correlates inversely with alpha6-lacZ expression: granule cells grown in 25 mM [K+]o for 11-15 d do not express the alpha6 gene, whereas cultures grown for the same period in 5 mM [K+]o do. This is influenced by a critical early period: culturing for >/=3 d in 25 mM [K+]o curtails the ability to induce the alpha6 gene on transfer to 5 mM [K+]o. If the cells start in 5 mM [K+]o, however, they still express the alpha6-lacZ gene in 25 mM [K+]o. In contrast to granule cells grown in 5 mM [K+]o, cells cultured in 25 mM [K+]o exhibit no action potentials, mEPSCs, or mIPSCs. In chronic 5 mM [K+]o, factors may therefore be released that induce alpha6. Blockade of ionotropic and metabotropic GABA and glutamate receptors or L-, N-, and P/Q-type Ca2+ channels did not prevent alpha6-lacZ expression, but inhibition of action potentials with tetrodotoxin blocked expression in a subpopulation of cells.

Characterization of an ecto-phosphorylated protein of cultured cerebellar granule neurons

Previous work identified the phosphorylation by extracellular ATP of an endogenous 45-kDa protein substrate and established the presence of ecto-protein kinase activity associated with cultured cerebellar granule neurons (Volonté et al.: J Neurochem 63:2028-2037, 1994). In this work, we characterize such ecto-phosphorylated 45-kDa protein substrate and its association with the cellular membrane. The total radioactive content of the 45-kDa protein is stable for the first 15 min after phosphorylation, and decreases about 70% in 30 min and 90% in approximately 2 hr. Rinsing the cells after the phosphorylating reaction causes a 50% removal of the incorporated radioactivity. Glycosidic residues are present on the 45-kDa ecto-protein, which is held in position on the cellular membrane through a specific glycosyl-phosphatidylinositol anchor. The extracellular incorporation of phosphate on the 45-kDa protein is not modulated by agents interfering with cytoskeleton stability, such as colchicine and taxol, or by gangliosides. The extracellular phosphorylation occurs mostly on serine residues, since the phosphate ester linkage is unstable at high pH and only antibodies raised against phosphoserine are capable of recognizing the 45-kDa ecto-protein.

Binding and functions of extracellular ATP in cultured cerebellar granule neurons

Selected purinoceptor modulators were previously shown to prevent glutamate-evoked cytotoxicity in cerebellar granule neurons. In the same cellular system, we now identify and characterize the presence of P2 receptors. The binding of [3H]ATP to membranes of cerebellar granule neurons grows monotonically as a function of neuronal differentiation, is saturable and reaches steady state within 6 min. Scatchard plot of the equilibrium saturation data is curvilinear with a Kd value of 28 nM and a Bmax value of 87 pmol/ mg of protein for the high affinity binding sites and a Kd value of 1.5 microM and Bmax value of 1.2 nmol/mg of protein, for the more numerous low affinity binding sites. We also show that extracellular ATP increases the release, but not the uptake, of [3H]D-aspartate and that it furthermore potentiates the release of [3H]D-aspartate evoked by glutamate and KCI. ATP itself is released by cerebellar granule cultures and such release grows monotonically as a function of neuronal differentiation. These data are consistent with the role that ATP is believed to play as a cotransmitter for the central nervous system.

Selected P2 purinoceptor modulators prevent glutamate-evoked cytotoxicity in cultured cerebellar granule neurons

Primary cultures of granule neurons derived from cerebella of postnatal rats are endowed with Glu receptors. Glu receptor agonists exert a trophic influence on differentiating granule cells but, with maturation, the cells become vulnerable to excitatory amino acids. Here we show that the P2 purinoceptor antagonist basilen blue abolishes in rat cerebellar granule neurons the cytotoxic action of glutamate with an IC50 in the 10-20 microM range. Within the same concentrations, basilen blue inhibits binding of [3H] ATP to cerebellar granule cells, glutamate-evoked release (but not uptake) of [3H] D-aspartate and Ca2+ uptake. Furthermore, the extracellular phosphorylation of a major 45-kDa endogenous ecto-protein substrate of cerebellar granule neurons is inhibited with an IC50 of about 1 microM. Similar effects are elicited by 5-adenylylimidodiphosphate, a P2 purinoceptor agonist, when supplied to the neurons for 8 days previously to the addition of glutamate. Our data point to the use of P2 purinoceptor modulators as novel elements for understanding and controlling glutamate-mediated excitatory neurotoxicity and neurotransmission. We suggest a possible involvement of P2 purinoceptors in these actions.

Identification of an ectokinase activity in cerebellar granule primary neuronal cultures

Primary neuronal cultures from 8-day-old rat cerebellum were incubated in the presence of exogenously added 16 nM [gamma-32P]ATP. Phosphorylation of a 45-kDa endogenous protein was detected within 1 min and increased linearly for approximately 20 min. Unlike what was seen with [gamma-32P]ATP, in the presence of [32P]orthophosphate no visible phosphorylation of protein was detected after 10 min, but a different pattern of phosphorylation was obtained in 30 min. The phosphorylation of the 45-kDa protein was reduced by 80-90% in the presence of 1 microM unlabeled ATP, 5 U/ml of apyrase, or 0.01% trypsin but not 1 mM PO4(3-). Phosphorylation was inversely proportional to cell density and was unaffected by addition to the cells of 56 mM KCl or 100 microM glutamate for 3 min. The presence of exogenously added cellular protein extracts or pretreatment of the cells for up to 20 min in phosphorylation buffer also did not affect the observed phosphorylation of the 45-kDa protein. The phosphorylation was found to be insensitive to MgCl2 but inhibited in the presence of MnCl2 or NaF and in the absence of CaCl2. Analogues of ATP suppressed phosphorylation of the 45-kDa protein by 80-90%. A similar inhibition was obtained in the presence of ADP or AMP. In this study, we establish via several different means that the phosphorylation of the 45-kDa protein in primary neuronal granule cultures occurs extracellularly through an ectokinase activity, which is furthermore distinguishable from a series of other presently characterized ecto-protein enzymes and intracellular kinases.