Pulmonary aspiration of gastric contents in two patients taking semaglutide for weight loss.

Semaglutide is a new weight loss treatment that has received substantial media attention in recent years. Anaesthetists must be aware of a potentially dangerous side effect of the drug: decreased gastric emptying. This is caused by effects on gastric smooth muscle, mediated by the vagal afferent nerves. This is especially relevant in the peri-operative setting where pulmonary aspiration of gastric contents is a recognised complication. Here, we report two cases of peri-operative regurgitation of gastric contents in patients taking semaglutide. A patient taking semaglutide may have a full stomach despite compliance with routine pre-operative fasting guidelines. We consider how to manage patients receiving glucagon-like peptide-1 agonist therapy in the peri-operative period, including identifying those at high risk of regurgitation. Precautions such as rapid sequence induction and tracheal intubation can be used, but gastric ultrasound may also be useful in the pre-operative environment to help identify patients at high risk of aspiration.

Amyloid-ß exposed astrocytes induce iron transport from endothelial cells at the blood-brain barrier by altering the ratio of apo- and holo-transferrin.

Excessive brain iron accumulation is observed early in the onset of Alzheimer's disease, notably prior to widespread proteinopathy. These findings suggest that increases in brain iron levels are due to a dysregulation of the iron transport mechanism at the blood-brain barrier. Astrocytes release signals (apo- and holo-transferrin) that communicate brain iron needs to endothelial cells in order to modulate iron transport. Here we use iPSC-derived astrocytes and endothelial cells to investigate how early-disease levels of amyloid-ß disrupt iron transport signals secreted by astrocytes to stimulate iron transport from endothelial cells. We demonstrate that conditioned media from astrocytes treated with amyloid-ß stimulates iron transport from endothelial cells and induces changes in iron transport pathway proteins. The mechanism underlying this response begins with increased iron uptake and mitochondrial activity by the astrocytes, which in turn increases levels of apo-transferrin in the amyloid-ß conditioned astrocyte media leading to increased iron transport from endothelial cells. These novel findings offer a potential explanation for the initiation of excessive iron accumulation in early stages of Alzheimer's disease. What's more, these data provide the first example of how the mechanism of iron transport regulation by apo- and holo-transferrin becomes misappropriated in disease that can lead to iron accumulation. The clinical benefit from understanding early dysregulation in brain iron transport in AD cannot be understated. If therapeutics can target this early process, they could possibly prevent the detrimental cascade that occurs with excessive iron accumulation.

Treatment of pediatric ocular rosacea: A systematic review.

BACKGROUND: Ocular rosacea is an underdiagnosed form of rosacea that may occur without typical cutaneous signs of rosacea. Manifestations include blepharitis, lid margin telangiectasias, and scleritis. A systematic comparison of treatment options for ocular rosacea in children is lacking. METHODS: A systematic review was conducted according to the PRISMA guidelines on treatment for pediatric ocular rosacea. RESULTS: Eleven articles were included, representing 135 patients with a mean age of 5 years, of whom 69% (n = 75/108) were female. 55% (n = 55/99) exhibited ocular symptoms prior to cutaneous symptoms. Most patients (83%, n = 34/41) experienced a delay in diagnosis (mean 27 months, range 2-120 months). Doxycycline was the most frequently reported treatment (25%, n = 33/135). A complete response was achieved in 33% of patients treated with doxycycline (n = 10/30), while 53% (n = 16/30) achieved a partial response. Erythromycin was used in 20% of cases (n = 26/135), with a complete response in 58% (n = 15/26) and partial response in 42% (n = 11/26). Metronidazole was used in 14% of patients (n = 19/135), with a complete response being reported in 79% (n = 15/19) and partial response in 21% (n = 4/19). CONCLUSION: Systemic antibiotics, led by doxycycline, were the most commonly reported treatment modalities for pediatric ocular rosacea. Increased awareness of ocular rosacea in this population is crucial for earlier diagnosis.

Amyloid-ß exposed astrocytes induce iron transport from endothelial cells at the blood-brain barrier by altering the ratio of apo- and holo-transferrin.

Excessive brain iron accumulation is observed in early in the onset of Alzheimer's disease, notably prior to widespread proteinopathy. These findings suggest that increases in brain iron levels are due to a dysregulation of the iron transport mechanism at the blood-brain barrier. Astrocytes release signals (apo- and holo-transferrin) that communicate brain iron needs to endothelial cells in order to modulate iron transport. Here we use iPSC-derived astrocytes and endothelial cells to investigate how early-disease levels of amyloid-ß disrupt iron transport signals secreted by astrocytes to stimulate iron transport from endothelial cells. We demonstrate that conditioned media from astrocytes treated with amyloid-ß stimulates iron transport from endothelial cells and induces changes in iron transport pathway protein levels. The mechanism underlying this response begins with increased iron uptake and mitochondrial activity by the astrocytes which in turn increases levels of apo-transferrin in the amyloid-ß conditioned astrocyte media leading to increased iron transport from endothelial cells. These novel findings offer a potential explanation for the initiation of excessive iron accumulation in early stages of Alzheimer's disease. What's more, these data provide the first example of how the mechanism of iron transport regulation by apo- and holo-transferrin becomes misappropriated in disease to detrimental ends. The clinical benefit from understanding early dysregulation in brain iron transport in AD cannot be understated. If therapeutics can target this early process, they could possibly prevent the detrimental cascade that occurs with excessive iron accumulation. Significance Statement: Excessive brain iron accumulation is hallmark pathology of Alzheimer's disease that occurs early in the disease staging and before widespread proteinopathy deposition. This overabundance of brain iron has been implicated to contribute to disease progression, thus understandingthe mechanism of early iron accumulation has significant therapeutic potential to slow to halt disease progression. Here, we show that in response to low levels of amyloid-ß exposure, astrocytes increase their mitochondrial activity and iron uptake, resulting in iron deficient conditions. Elevated levels of apo (iron free)-transferrin stimulate iron release from endothelial cells. These data are the first to propose a mechanism for the initiation of iron accumulation and the misappropriation of iron transport signaling leading to dysfunctional brain iron homeostasis and resultant disease pathology.

The Involvement of Lumican in Human Ovulatory Processes.

Based on a previous global transcriptome sequencing project, we hypothesized that Lumican (LUM) might play a role in ovulatory processes. We sought to determine LUM gene expression under various conditions in human preovulatory follicles. The in vitro expression of LUM mRNA in mural (MGCs) and cumulus (CGCs) granulosa cells was characterized using quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical staining was used to identify human LUM expression in follicles at different developmental stages. Cell signaling studies were performed by treating human MGCs with human chorionic gonadotropin (hCG) and both, different stimulators and inhibitors to determine their effect on LUM expression by using qRT-PCR. Cell confluence studies were carried out to study the correlation between LUM expression and follicle cell proliferation. Follicular MGCs and CGCs of women undergoing in vitro fertilization (IVF) procedures due to endometriosis were analyzed for differences in LUM expression patterns by qRT-PCR. LUM mRNA expression was significantly higher in MGCs as compared to CGCs. In CGCs, LUM mRNA was higher in mature metaphase II (MII) oocytes than in germinal vesicle (GV) and metaphase I (MI) oocytes. LUM expression was significantly upregulated in response to hCG in cultured MGCs. Immunohistochemistry of human ovaries revealed LUM was mostly present in MGCs of large preovulatory and postovulatory follicles and absent from primordial follicles. Using pharmacological activators and inhibitors, we demonstrated that LUM induction by luteinizing hormone (LH)/hCG is carried through the mitogen-activated protein kinase (MEK) pathway. LUM expression was induced in high-density cell cultures in a confluence-dependent manner. MGCs from follicles of subjects with endometriosis exhibited reduced mRNA transcription levels compared to control subjects. Our study confirms that LUM is a newly discovered ovulatory gene. LUM might play an important role during the preovulatory period up until ovulation as well as in endometriosis infertility. A better understanding of LUM's role might provide potential new treatment paradigms for some types of female infertility.

Day 5 vitrified blastocyst transfer versus day 6 vitrified blastocyst transfer in oocyte donation program.

The superiority of day 5 blastocysts compared to day 6 blastocysts in fresh cycle transfers was previously demonstrated and attributed mainly to endometrial asynchrony. Data from frozen blastocysts transfers showed conflicting results, possibly due to heterogeneous patient population and embryo quality. The aim of this study was to compare clinical pregnancy rate (CPR) and live birth rate (LBR) between transfers of vitrified day 5 blastocysts and day 6 blastocysts in oocyte donation, blastocyst-only cycles. In a retrospective, multi-center study, with a single oocyte donation program, a total of 1840 frozen embryo transfers (FET's) were analyzed, including 1180 day 5 blastocysts and 660 day 6 blastocysts transfers. Day 5 blastocyst transfers had better embryonic development and significantly higher CPRs (34.24% vs. 20.15%, P < 0.0001), higher LBRs (26.89% vs. 14.77%, P < 0.0001), less cycles to LBR (1.83 ± 0.08 vs. 2.39 ± 0.18, P = 0.003) and shorter time to LBRs (76.32 ± 8.7 vs. 123.24 ± 19.1 days, P = 0.01), compared to day 6 transfers, respectively. A multivariate stepwise logistic regression indicated, that day 5 transfer was an independent factor for CPRs (OR 1.91; 95% CI 1.43-2.54, P < 0.001) and LBRs (OR 2.26; 95% CI 1.19-4.28, P = 0.01), regardless of embryo quality, compared to day 6. In conclusion, day 5 blastocysts in oocyte donation program have significantly higher CPRs and LBRs, and present shorter time to delivery, compared to day 6 blastocysts, regardless of embryo quality.

Does residual microscopic disease after chemoradiotherapy for locally advanced rectal cancer translate into a good clinical outcome?

AIM: This study aimed to assess the progression-free and overall survival of patients with residual microscopic disease following neoadjuvant chemoradiotherapy and rectal resection for locally advanced rectal cancer. METHOD: Two-hundred and thirty-four consecutive rectal cancer patients who had neoadjuvant chemoradiotherapy followed by radical resection (from May 2000 to April 2012) were divided according to pathological tumour response: residual microscopic disease (MIC), complete response (pCR) and partial/no response (non-CR). Data on the neoadjuvant regime, treatment-to-surgery interval, final pathology, type of operation, operative time, postoperative complications, length of hospital stay, disease recurrence and mortality were compared between the groups. RESULTS: There were 13 (5.5%) MIC patients, 48 (20.5%) with pCR and 173 (73.9%) with non-CR group. The groups were demographically comparable. MIC patients had more retrieved lymph nodes compared with the non-CR and pCR patients (median 13 compared with 8 and 10, respectively, P = 0.0086). The 5-year overall survival rates were 93.4% for the pCR and MIC patients vs 82.1% for the non-CR patients (P = 0.0324). The 5-year progression-free survival was 85.2% for the pCR and MIC patients vs 73.8% for the non-CR patients (P = 0.086). CONCLUSION: We have identified and assessed a new pathological subgroup of rectal cancer patients who had residual microscopic disease after neoadjuvant therapy. The survival analysis aligned them closely with pCR patients.

Impaired neurogenesis by HIV-1-Gp120 is rescued by genetic deletion of fatty acid amide hydrolase enzyme.

BACKGROUND AND PURPOSE: The HIV-envelope glycoprotein Gp120 is involved in neuronal injury and is associated with neuro-AIDS pathogenesis in the brain. Endocannabinoids are important lipid ligands in the CNS regulating neural functions, and their degeneration is controlled by hydrolysing enzymes such as the fatty acid amide hydrolase (FAAH). Here, we examined whether in vivo genetic deletion of Faah gene prevents HIV-1 Gp120-mediated effects on neurogenesis. EXPERIMENTAL APPROACH: We generated new GFAP/Gp120 transgenic (Tg) mice that have genetic deletion of Faah gene by mating glial fribillary acidic protein (GFAP)/Gp120 Tg mice with Faah-/- mice. Neurogenesis and cell death were assessed by immunocytochemical analysis. KEY RESULTS: Endocannabinoid levels in the brain of the double GFAP/Gp120//Faah-/- mice were similar to those observed in Faah-/- mice. However, unlike the impaired neurogenesis observed in GFAP/Gp120 Tg mice and Faah-/- mice, these GFAP/Gp120//Faah-/ mice showed significantly improved neurogenesis in the hippocampus, indicated by a significant increase in neuroblasts and neuronal cells, an increase in BrdU(+) cells and doublecortin positive cells (DCX(+) ), and an increase in the number of PCNA. Furthermore, a significant decrease in astrogliosis and gliogenesis was observed in GFAP/Gp120//Faah-/-mice and neurogenesis was stimulated by neural progenitor cells (NPCs) and/or the newly formed NPC niches characterized by increased COX-2 expression and elevated levels of PGE2 . CONCLUSIONS AND IMPLICATIONS: In vivo genetic ablation of Faah, resulted in enhanced neurogenesis through modulation of the newly generated NPC niches in GFAP/Gp120//Faah-/- mice. This suggests a novel approach of using FAAH inhibitors to enhance neurogenesis in HIV-1 infected brain.

NRP/B mutations impair Nrf2-dependent NQO1 induction in human primary brain tumors.

Brain tumors are associated with genetic alterations of oncogenes and tumor suppressor genes. Accumulation of reactive oxygen species (ROS) in cells leads to oxidative stress-induced damage, resulting in tumorigenesis. Here, we showed that the nuclear matrix protein nuclear restricted protein in brain (NRP/B) was colocalized and interacted with NF-E2-related factor 2 (Nrf2). During oxidative stress response, NRP/B expression and its interaction with Nrf2 were upregulated in SH-SY5Y cells. Association of NRP/B with Nrf2 was crucial for NAD(P)H:quinone oxidoreductase 1 (NQO1) expression. NRP/B was localized predominantly in the nucleus of normal brain cells, whereas in primary brain tumors NRP/B was almost exclusively contained in the cytoplasm. In addition, unlike wild-type NRP/B, the expression of NRP/B mutants isolated from primary brain tumors was found in the cytoplasm, and these mutants failed to induce Nrf2-dependent NQO1 transcription. Thus, NRP/B mutations and their altered localization resulted in changes in NRP/B function and deregulation of Nrf2-dependent NQO1 activation in brain tumors. This study provides insights into the mechanism by which the NRP/B modulates Nrf2-dependent NQO1 induction in cellular protection against ROS in brain tumors.

Oral integrity and salivary profile in myeloma patients undergoing high-dose therapy followed by autologous SCT.

The underlying mechanism of high-dose therapy (HDT)-related oral mucositis (OM) may be partly mediated by alterations in the normal salivary composition. This study evaluated salivary antioxidant and immunological capacities observed in myeloma patients suffering from HDT-related OM, and assessed potential contribution of these factors to OM development. Twenty-five consecutive myeloma patients treated with melphalan 200 mg/m(2) followed by autologous SCT were enrolled. Patients underwent a daily assessment for OM, and salivary samples were collected on days -3 and +7 of transplantation and analyzed for secretory IgA and antioxidant capacity. The degree of mucosal damage was assessed by measuring the salivary carbonyl and albumin (Alb) levels. OM, reported in 96% of patients, appeared to be most severe on 8 day after transplantation (range: +2 to +14). Clinical mucositis was associated with significant reduction in salivary secretory IgA (54%; P=0.05), and antioxidant activity, measured by total antioxidant status (40%; P=0.0004), antioxidant capacity (ImAnOx) (23%; P=0.002) and uric acid level (51%; P=0.006). The increase found in salivary Alb (119%; P=0.024) and carbonyl (28%; P=0.047) levels, indicates mucosal and oxidative damage, respectively. These salivary changes might enhance mucositis development and symptoms. Therapeutic interventions, enhancing antioxidative and immunological activities need to be investigated.

A mutation analysis of the phenylalanine hydroxylase (PAH) gene in the Israeli population.

Hyperphenylalaninemia (HPA) is a group of diseases characterized by a persistent elevation of phenylalanine levels in tissues and biological fluids. The most frequent form is phenylalanine hydroxylase deficiency, causing phenylketonuria (PKU). Among 159 Israeli patients (Jews, Muslim and Christian Arabs and Druze) with HPA, in whom at least one of the mutations was characterized, a total of 43 different mutations were detected, including seven novel ones. PKU was very rare among Ashkenazi Jews and relatively frequent among Jews from Yemen, the Caucasian Mountains, Bukhara and Tunisia. The mutations responsible for the high frequency were: exon3del (Yemenite Jews), L48S (Tunisian Jews) and E178G, P281L and L48S (Jews from the Caucasian Mountains and Bukhara). Among the non-Jewish Israeli citizens, the disease was relatively frequent in the Negev and in the Nazareth vicinity, and in many localities a unique mutation was detected, often in a single family. While marked genetic heterogeneity was observed in the Arab and Jewish populations, only one mutation A300S, was frequent in all of the communities. Several of the other frequent mutations were shared by the non-Ashkenazi Jews and Arabs; none were mutual to Ashkenazi Jews and Arabs.

RAFTK/Pyk2 involvement in platelet activation is mediated by phosphoinositide 3-kinase.

Platelet activation by different agonists initiates a signalling cascade involving the phosphorylation of several protein kinases, which control key regulatory events. Previously, we demonstrated that the related adhesion focal tyrosine kinase (RAFTK, Pyk2) was involved in an early phase of platelet activation, independent of integrin and glycoprotein IIb-IIIa activation. In this study, we demonstrate that RAFTK is co-immunoprecipitated with phosphoinositide 3-kinase (PI3K) upon platelet activation, and that thrombin, ADP and collagen induced the phosphorylation of both PI3K and RAFTK. A low dose of thrombin (0.015 U/ml) induced RAFTK phosphorylation and platelet aggregation in a PI3K activity-dependent manner, whereas a high dose of thrombin (0.1 U/ml) induced these events in a PI3K activity-independent manner. ADP and collagen also induced RAFTK phosphorylation and platelet aggregation in a PI3K activity-dependent manner, similar to that of the low-dose thrombin. Furthermore, protein tyrosine phosphatase activity was associated with RAFTK in response to platelet activation, and was found to be that of protein tyrosine phosphatase-2 (SHP-2). The association of SHP-2 with RAFTK was PI3K-dependent and was increased upon RAFTK phosphorylation. Taken together, our results strongly suggest that the involvement of RAFTK in platelet activation is mediated via the PI3K pathway.

Histopathology of the inferior turbinate with compensatory hypertrophy in patients with deviated nasal septum.

OBJECTIVE: To measure the dimensions, composition, and possible structural and/or histopathological changes of the compensatory hypertrophic inferior turbinate in patients with deviated nasal septum. STUDY DESIGN: A prospective, nonrandomized, and morphometric study. METHODS: Nineteen patients with deviated nasal septum and compensatory hypertrophy of the inferior turbinate in the contralateral nasal cavity underwent surgery for correction of nasal obstruction. Patients' specimens were compared with those of a control group consisting of 10 inferior turbinates removed at autopsy. Quantitative measurements of the inferior turbinate histological sections were carried out and included the width of the layers and morphometric calculations of the relative proportions of the soft tissue constituents. Also, qualitative study was performed to detect pathological changes. RESULTS: Of all layers, the inferior turbinate bone underwent a twofold increase in thickness and manifested the most significant expansion (P < or =.001), whereas the contribution of the mucosal layers to the inferior turbinate hypertrophy was modest. The morphometric analysis revealed a larger proportion of venous sinusoids in hypertrophic turbinates, but the difference was small and statistically insignificant. Qualitative assessment disclosed normal mucosal architecture in all inferior turbinates with compensatory hypertrophy. Eleven remained intact, while eight disclosed mild to moderate pathological changes. CONCLUSIONS: The data gathered in the present study are of importance to the decision-making process regarding turbinate surgery. The significant bone expansion and the relative minor role played by the mucosal hypertrophy would support the decision to excise the inferior turbinate bone at the time of septoplasty.

Genomic organization, chromosomal localization and regulation of expression of the neuronal nuclear matrix protein NRP/B in human brain tumors.

The nuclear matrix and its role in cell physiology are largely unknown, and the discovery of any matrix constituent whose expression is tissue- and/or cell-specific offers a new avenue of exploration. Studies of the novel neuronal nuclear matrix protein, NRP/B, reveal that it is an early and highly specific marker of neuronal induction and development in vertebrates, since its expression is restricted mainly to the developing and mature nervous system. These studies also show that NRP/B is involved in neuronal differentiation. To further examine the structure-function of NRP/B, we have cloned and characterized the murine Nrp/b gene. The murine gene consists of four exons interrupted by three introns that span 7.6kb of DNA. The complete open reading frame is localized in exon 3, suggesting that NRP/B is highly conserved during evolution. Chromosomal analysis shows that NRP/B is localized to chromosome 13 in mouse and chromosome 5q12-13 in human. Since our previous studies demonstrated that NRP/B is expressed in primary hippocampal neurons but not in primary astrocytes, we have characterized NRP/B mRNA and protein expression in various brain cell lines and in human brain tumors. Abundant expression of NRP/B mRNA and protein was observed in human neuroblastoma cell lines (IMR32, SKN-MC, SKN-SH), in glioblastoma cell lines (A172, T98G, U87-MG, U118-MG, U138-MG, and U373-MG), in neuroglioma (H4) and astrocytoma cell lines (CCF-STTG1 and SW1088). Confocal analysis of NRP/B in U87-MG glioblastoma cells indicated nuclear localization of NRP/B. NRP/B expression was also observed in human primary brain tumors including glioblastoma multiformae and astrocytomas (total of five cases). These results suggest that NRP/B expression is upregulated in human brain tumors including glioblastomas and astrocytomas, while under normal conditions NRP/B expression is restricted to neurons. This study implicates a role for NRP/B in brain tumor development.

Receptor protein tyrosine phosphatases in hematopoietic cells.

PTPs and PTKs control the level of tyrosine phosphorylation of cellular proteins. Although many substrates for PTKs have been identified, the specific targets of individual PTP family members, along with the consequences of protein dephosphorylation for cellular physiology, remain largely unknown. Fine regulation of tyrosine phosphorylation events is required for the proper progression of hematopoiesis. In this review, we have summarized the characterization of tyrosine phosphatases in hematopoietic cells and delineated their potential role in the process of hematopoiesis and the development of hematopoietic disorders.

SHP2 mediates the protective effect of interleukin-6 against dexamethasone-induced apoptosis in multiple myeloma cells.

Our previous studies have shown that activation of a related adhesion focal tyrosine kinase (RAFTK) (also known as Pyk2) is required for dexamethasone (Dex)-induced apoptosis in multiple myeloma (MM) cells and that human interleukin-6 (IL-6), a known growth and survival factor for MM cells, blocks both RAFTK activation and apoptosis induced by Dex. However, the mechanism whereby IL-6 inhibits Dex-induced apoptosis is undefined. In this study, we demonstrate that protein-tyrosine phosphatase SHP2 mediates this protective effect. We show that IL-6 triggers selective activation of SHP2 and its association with RAFTK in Dex-treated MM cells. SHP2 interacts with RAFTK through a region other than its Src homology 2 domains. We demonstrate that RAFTK is a direct substrate of SHP2 both in vitro and in vivo, and that Tyr(906) in the C-terminal domain of RAFTK mediates its interaction with SHP2. Moreover, overexpression of dominant negative SHP2 blocked the protective effect of IL-6 against Dex-induced apoptosis. These findings demonstrate that SHP2 mediates the anti-apoptotic effect of IL-6 and suggest SHP2 as a novel therapeutic target in MM.

The tyrosine kinase PYK-2/RAFTK regulates natural killer (NK) cell cytotoxic response, and is translocated and activated upon specific target cell recognition and killing.

The compartmentalization of plasma membrane proteins has a key role in regulation of lymphocyte activation and development of immunity. We found that the proline-rich tyrosine kinase-2 (PYK-2/RAFTK) colocalized with the microtubule-organizing center (MTOC) at the trailing edge of migrating natural killer (NK) cells. When polyclonal NK cells bound to K562 targets, PYK-2 translocated to the area of NK-target cell interaction. The specificity of this process was assessed with NK cell clones bearing activatory or inhibitory forms of CD94/NKG2. The translocation of PYK-2, MTOC, and paxillin to the area of NK-target cell contact was regulated upon specific recognition of target cells through NK cell receptors, controlling target cell killing. Furthermore, parallel in vitro kinase assays showed that PYK-2 was activated in response to signals that specifically triggered its translocation and NK cell mediated cytotoxicity. The overexpression of both the wt and a dominant-negative mutant of PYK-2, but not ZAP-70 wt, prevented the specific translocation of the MTOC and paxillin, and blocked the cytotoxic response of NK cells. Our data indicate that subcellular compartmentalization of PYK-2 correlates with effective signal transduction. Furthermore, they also suggest an important role for PYK-2 on the assembly of the signaling complexes that regulate the cytotoxic response.

Glutamate-stimulated activation of DNA synthesis via mitogen-activated protein kinase in primary astrocytes: involvement of protein kinase C and related adhesion focal tyrosine kinase.

Glutamate is the major excitatory neurotransmitter in the CNS. Although its role in neurons has been studied extensively, little is known about its function in astrocytes. We studied the effects of glutamate on signaling pathways in primary astrocytes. We found that the tyrosine kinase related adhesion focal tyrosine kinase (RAFTK) is tyrosine phosphorylated in response to glutamate in a time- and dose-dependent manner. This phosphorylation was pertussis toxin (PTX) sensitive and could be attenuated by the depletion of Ca2+ from intracellular stores. RAFTK tyrosine phosphorylation was mediated primarily by class I/II metabotropic glutamate receptors and depends on protein kinase C (PKC) activation. Glutamate treatment of primary astrocytes also results in a significant increase in the activity of the mitogen-activated protein kinases [extracellular signal-related kinases 1/2 (ERK1/2)]. Like RAFTK phosphorylation, ERK1/2 activation is PTX sensitive and can be attenuated by the depletion of intracellular Ca2+ and by PKC inhibition, suggesting that RAFTK might mediate the glutamate-dependent activation of ERK1/2. Furthermore, we demonstrated that glutamate stimulation of primary astrocytes leads to a significant increase in DNA synthesis. Glutamate-stimulated DNA synthesis is PTX sensitive and can be inhibited by the MAP kinase kinase inhibitor PD98059, suggesting that in primary astrocytes, glutamate might signal via RAFTK and MAP kinase to promote DNA synthesis and cell proliferation.

Characterization of the tyrosine kinases RAFTK/Pyk2 and FAK in nerve growth factor-induced neuronal differentiation.

The related adhesion focal tyrosine kinase (RAFTK), a member of the focal adhesion kinase (FAK) family and highly expressed in brain, is a key mediator of various extracellular signals that elevate intracellular Ca(2+) concentration. We investigated RAFTK and FAK signaling upon nerve growth factor (NGF) stimulation of PC12 cells. NGF induced the tyrosine phosphorylation of RAFTK in a time- and dose-dependent manner, whereas no change in the tyrosine phosphorylation of FAK was observed. Chemical inhibition showed that RAFTK phosphorylation was inhibited by blocking phospholipase Cgamma activity or intracellular Ca(2+). Blocking of extracellular Ca(2+) or phosphatidylinositol 3-kinase activity partially reduced the phosphorylation of RAFTK. In addition, disruption of actin polymerization abolished RAFTK phosphorylation, indicating that an intact actin-based cytoskeletal organization is required for RAFTK phosphorylation. The focal adhesion molecule paxillin was co-immunoprecipitated with RAFTK, and its tyrosine phosphorylation was increased in a Ca(2+)-dependent manner upon NGF stimulation. Confocal microscopic analysis demonstrated that RAFTK translocated from the cytoplasm to potential neurite initiation sites at the cell periphery, where RAFTK co-localized with paxillin and bundled actin in the early phase (within 5 min) of NGF stimulation, whereas FAK co-localized with paxillin at "point contacts," which are the primary cell adhesion sites in neuronal cells. Significant distribution of RAFTK was observed in the neurites and growth cones of differentiated PC12 cells. Furthermore, potassium depolarization induced the tyrosine phosphorylation of both RAFTK and paxillin in an intracellular Ca(2+)-dependent manner in the differentiated PC12 cells. Taken together, these results demonstrate that RAFTK is involved in NGF-induced cytoskeletal organization and may play a role in neurite and growth cone function(s).

Vascular endothelial growth factor up-regulates ICAM-1 expression via the phosphatidylinositol 3 OH-kinase/AKT/Nitric oxide pathway and modulates migration of brain microvascular endothelial cells.

Endothelium of the cerebral blood microvessels, which constitutes the major component of the blood-brain barrier, controls leukocyte and metastatic cancer cell adhesion and trafficking into the brain parenchyma. In this study, using rat primary brain microvascular endothelial cells (BMEC), we demonstrate that the vascular endothelial growth factor (VEGF), a potent promoter of angiogenesis, up-regulates the expression of the intracellular adhesion molecule-1 (ICAM-1) through a novel pathway that includes phosphatidylinositol 3 OH-kinase (PI3K), AKT, and nitric oxide (NO), resulting in the migration of BMEC. Upon VEGF treatment, AKT is phosphorylated in a PI3K-dependent manner. AKT activation leads to NO production and release and activation-deficient AKT attenuates NO production stimulated by VEGF. Transfection of the constitutive myr-AKT construct significantly increased basal NO release in BMEC. In these cells, VEGF and the endothelium-derived NO synergistically up-regulated the expression of ICAM-1, which was mediated by the PI3K pathway. This activity was blocked by the PI3K-specific inhibitor, wortmannin. Furthermore, VEGF and NO significantly increased BMEC migration, which was mediated by the up-regulation of ICAM-1 expression and was dependent on the integrity of the PI3K/AKT/NO pathway. This effect was abolished by wortmannin, by the specific ICAM-1 antibody, by the specific inhibitor of NO synthase, N(G)-l-monomethyl-arginine (l-NMMA) or by a combination of wortmannin, ICAM-1 antibody, and l-NMMA. These findings demonstrate that the angiogenic factor VEGF up-regulates ICAM-1 expression and signals to ICAM-1 as an effector molecule through the PI3K/AKT/NO pathway, which leads to brain microvessel endothelial cell migration. These observations may contribute to a better understanding of BMEC angiogenesis and the physiological as well as pathophysiological function of the blood-brain barrier, whose integrity is crucial for normal brain function.