D-Serine is a co-agonist at the NMDA receptor glycine-binding site. Early studies have emphasized a glial localization for D-serine. However the nature of the glial cells has not been fully resolved, because previous D-serine antibodies needed glutaraldehyde-fixation, precluding co-localization with fixation-sensitive antigens. We have raised a new D-serine antibody optimized for formaldehyde-fixation. Light and electron microscopic observations indicated that D-serine was concentrated into vesicle-like compartments in astrocytes and radial glial cells, rather than being distributed uniformly in the cytoplasm. In aged animals, patches of cortex and hippocampus were devoid of immunolabeling for D-serine, suggesting that impaired glial modulation of forebrain glutamatergic signaling might occur. Dual immunofluorescence labeling for glutamate and D-serine revealed D-serine in a subset of glutamatergic neurons, particularly in brainstem regions and in the olfactory bulbs. Microglia also contain D-serine. We suggest that some D-serine may be derived from the periphery. Collectively, our data suggest that the cellular compartmentation and distribution of D-serine may be more complex and extensive than previously thought and may have significant implications for our understanding of the role of D-serine in disease states including hypoxia and schizophrenia.

No abstract

The induction of GLT-1c expression by retinal ganglion cells supports the notion that an anomaly or anomalies in glutamate homeostasis may be evident in glaucoma and that such anomalies selectively influence retinal ganglion cells. By analogy to in vitro experiments in which elevated glutamate levels induce expression of glutamate transporters, the authors hypothesize that expression of GLT-1c may represent an attempt by retinal ganglion cells to protect themselves against elevated levels of glutamate. Such anomalies in glutamate levels cannot be restricted to the ganglion cell layer, as this would not have affected displaced ganglion cells. GLT-1c may be a useful indicator of the extent of stress of the retinal ganglion cells and thus a tool for examining outcomes of potential therapeutic and experimental interventions.

No abstract

We have raised antibodies that selectively recognize an exon 9 skipping form of GLAST. We demonstrate expression of this protein in brains of rats, cats, monkeys and humans. Immunolabelling was present in scattered populations of neurons, particularly in cerebral cortex and colliculi. Neurons were often present in small clusters and exhibited a range of morphologies, from apparently normal to highly degenerate. GLAST1b was also expressed by some glial cells. Cortical neurons expressing the exon 9 skipping form of GLAST also labelled with antibodies against the C- or N-terminal regions of GLAST. We suggest that alternate splicing of GLAST by subpopulations of neurons may indicate some dysfunction in these cells, and may be an indicator of inappropriate local excitation.

No abstract

GLAST is a glial glutamate transporter; mRNA for a splice variant, GLAST1a, which lacks exon 3, has previously been identified. To detect GLAST1a protein, we generated antibodies against a peptide sequence encompassing the splice site. We demonstrate by Western blotting and immunocytochemistry the expression of GLAST1a in brains and retinae. Robust immunolabelling was present in the cerebellar Bergmann glia, and weaker labelling was evident in the retinal Müller cells. GLAST1a is differentially targeted to some cellular compartments such as the end feet of the Müller cells. As GLAST1a protein may interfere with the transport of glutamate by normally spliced GLAST, differentially targeted expression of GLAST1a may represent a mechanism for selectively regulating GLAST function in the mammalian nervous system.

BACKGROUND: We conducted a Phase 1 study to evaluate safety and activity of olaparib tablets and oral cyclophosphamide. METHODS: Patients had metastatic breast cancer (BC) or recurrent high-grade serous ovarian cancer (HGSOC), performance status 0-2, and ≤3 lines of prior therapy. Patients were treated using a dose escalation strategy with cohort expansion once maximal tolerated dose (MTD) was determined. Dose level 1 (DL1): olaparib 300 mg bid, cyclophosphamide 50 mg on days 1, 3, and 5, weekly. DL2: olaparib 300 mg bid, cyclophosphamide 50 mg, days 1-5 weekly. RESULTS: Of 32 patients, 23 had HGSOC (germline BRCA mutation [gBRCAm] 70%) and 9 had BC (gBRCAm 67%). Four were treated at DL1 and 28 at DL2, the MTD. Haematological adverse events (AEs) were most common: grade 3/4 AEs: lymphopenia 75%, anaemia 31%, neutropenia 37%, thrombocytopenia 47%. Two permanently discontinued treatment due to haematological AEs. In BC, no objective response was reported. Unconfirmed objective response was 48% and 64% for all HGSOC and gBRCAm subset, respectively. CA125 responses were 70% (all HGSOC) and 92% (gBRCAm). CONCLUSIONS: In HGSOC and BC, olaparib 300 mg bid and cyclophosphamide 50 mg on days 1-5 weekly were tolerable and active, particularly in gBRCAm, and is worthy of further investigation.