Two new species of gall midges (Diptera, Cecidomyiidae) associated with Erythroxylum ovalifolium Peyr. (Erythroxylaceae) from the Barra de Maricá restinga, Maricá, Rio de Janeiro, Brazil.

Two new species of gall midges (Diptera, Cecidomyiidae) Dasineura ovalifoliae and Clinodiplosis maricaensis are described based on material from the Barra de Maricá restinga, Maricá, Rio de Janeiro, Brazil. Both species are associated with Erythroxylum ovalifolium Peyr. (Erythroxylaceae). The former is the gall inducer and the latter an inquiline.

Inactivation of astrocytic glutamine synthetase by hydrogen peroxide requires iron.

The specific activity of brain glutamine synthetase (GS) is lowered in several neurodegenerative diseases that involve iron-mediated oxidative stress. The present study has investigated whether H2O2 directly inactivates GS or whether GS is primarily inactivated by hydroxyl radicals that are produced by the Fenton reaction when H2O2 reacts with ferrous iron. Exposure of purified sheep brain GS to supraphysiological concentrations of H2O2 (1 mM for 30 min) reduced its specific activity by only 41%, indicating that the enzyme is fairly resistant to oxidation by peroxide. However, the enzyme was completely inactivated when co-incubated with H2O2, iron and ascorbate, indicating a vulnerability to oxidation by conditions that favour the production of hydroxyl radicals. Similarly, specific GS activity in cultured mouse astrocytes was resistant to supraphysiological concentrations of H2O2, with approximately 37% of activity remaining 3h after incubation with 1mM H2O2. This inactivation was prevented by the iron chelators 2,2'-dipyridyl or 1,10-phenanthroline, but not by their non-chelating analogues. These data suggest that inactivation of astrocytic GS is caused by H2O2 indirectly via the Fenton reaction as it required the presence of chelatable intracellular iron.

HIV-1 protein gp120 rapidly impairs memory in chicks by interrupting the glutamate-glutamine cycle.

Learning and memory impairments are frequently observed in patients suffering from AIDS Dementia Complex (ADC). These effects have been linked to the presence of gp120, an HIV viral coat glycoprotein. The present study investigated the possibility that gp120 prevents the uptake of extracellular glutamate by astrocytes, leading to an interruption of the glutamate-glutamine cycle and a subsequent impairment of memory. Ten microliters of 10nM gp120 was bilaterally injected into the region of the intermediate medial mesopallium of day-old chicks at various times before, or after, training using a single-trial passive avoidance task. Gp120 was found to significantly impair memory retention when injected 10-40 min after training. Memory impairments were evident within 5 min of gp120 administration and remained evident 24h later. Further, the amnestic effect of gp120 could be overcome with glutamine or with precursors of glutamate synthesis, but only weakly by glutamate. These results support the conclusion that the amnestic effect of gp120 is due to an impaired uptake of glutamate by astrocytes and a subsequent interruption of glutamine supply to neurones. The data indicate that the glutamate-glutamine cycle may be a useful therapeutic target in the treatment of ADC.

Tumorlike clusters of immature cells in cerebrospinal fluid of infants.

Cerebrospinal fluid (CSF) samples from four infants 3 days to 4 months of age with a history of prematurity or birth trauma were found to contain clusters of immature cells. These cells were arranged in groups or syncytia, sometimes with nuclear molding, and were cytologically characterized by scant basophilic cytoplasm, nuclei with fine nuclear chromatin, and small nucleoli. The picture simulated the appearance of metastatic tumor admixed with hemosiderin-laden macrophages, erythrocytes, and leukocytes. Because of the low numbers of cells or aggregates present in CSF samples and the relatively small quantity of CSF obtained, immunohistochemical and flow cytometric evaluations were not performed. Prior studies have designated these immature cells as undifferentiated leptomeningeal cells or cells from the subependymal germinal matrix and have associated their presence with intraventricular hemorrhage (IVH) in premature newborns. Three of our patients had a history of prematurity; the fourth patient suffered a traumatic birth but was not premature. In long-term follow-up, the patients have not shown progression of neurologic deficits or evidence of malignancy. Thus, it is important to recognize that in infants with a history of IVH, subarachnoid hemorrhage, or ventricular drainage devices, the presence of tumorlike clumps of cells associated with hemosiderin-laden macrophages most likely does not represent metastatic tumor.