Activated monocytes release a number of substances, including inflammatory cytokines and eicosanoids, that are highly toxic to cells of the central nervous system. Because monocytic infiltration of ...the central nervous system closely correlates with HIV-1-associated dementia, it has been suggested that monocyte-derived toxins mediate nervous system damage. In the present study, we show that the HIV-1 transactivator protein Tat significantly increases astrocytic expression and release of monocyte chemoattractant protein-1 (MCP-1). Astrocytic release of β -chemokines, which are relatively less selective for monocytes, including RANTES, macrophage inflammatory protein-1α , and macrophage inflammatory protein-1β , was not observed. We also show that MCP-1 is expressed in the brains of patients with HIV-1-associated dementia and that, of the β -chemokines tested, only MCP-1 could be detected in the cerebrospinal fluid of patients with this condition. Together, these data provide a potential link between the presence of HIV-1 in the brain and the monocytic infiltration that may substantially contribute to dementia.
Objective
To define left temporal lobe regions where surgical resection produces a persistent postoperative decline in naming visual objects.
Methods
Pre‐ and postoperative brain magnetic resonance ...imaging data and picture naming (Boston Naming Test) scores were obtained prospectively from 59 people with drug‐resistant left temporal lobe epilepsy. All patients had left hemisphere language dominance at baseline and underwent surgical resection or ablation in the left temporal lobe. Postoperative naming assessment occurred approximately 7 months after surgery. Surgical lesions were mapped to a standard template, and the relationship between presence or absence of a lesion and the degree of naming decline was tested at each template voxel while controlling for effects of overall lesion size.
Results
Patients declined by an average of 15% in their naming score, with wide variation across individuals. Decline was significantly related to damage in a cluster of voxels in the ventral temporal lobe, located mainly in the fusiform gyrus approximately 4‐6 cm posterior to the temporal tip. Extent of damage to this region explained roughly 50% of the variance in outcome. Picture naming decline was not related to hippocampal or temporal pole damage.
Significance
The results provide the first statistical map relating lesion location in left temporal lobe epilepsy surgery to picture naming decline, and they support previous observations of transient naming deficits from electrical stimulation in the basal temporal cortex. The critical lesion is relatively posterior and could be avoided in many patients undergoing left temporal lobe surgery for intractable epilepsy.
Premise of the study: Discovering missing ancestors is essential to understanding the evolutionary history of biodiversity on Earth. Evidence from extinct species can provide links for reconstructing ...intricate patterns of reticulate relationships among extant descendents. When fossils are unavailable and other evidence yields competing hypotheses to explain species ancestry, data from proteins and DNA can help resolve conflicts and generate novel perspectives. The identity of a parent shared by two tetraploid species in the cosmopolitan fern genus Dryopteris has remained elusive for more than 50 years. Based on available data, four hypotheses were developed previously, each providing a different resolution to this uncertainty. METHODS: New molecular evidence from studies of isozymes and restriction site analysis of chloroplast DNA tested the competing hypotheses about the diploid ancestors of these two extant Dryopteris polyploids. Key results: The results falsify two of the hypotheses, resolve the uncertainty in the third, and support the fourth. CONCLUSIONS: Our data validate the prior existence of Dryopteris "semicristata," which was proposed 38 years ago as a diploid progenitor of the allotetraploids D. cristata and D. carthusiana but has never been collected. After developing a phylogeny using the new molecular data, we describe a plausible morphology for D. "semicristata" by extrapolating likely character states from related extant species.
The release of potentially neurotoxic molecules by HIV‐infected brain macrophages is accompanied by neuronal injury and death that results in the development of HIV‐associated dementia (HAD). Among ...the potential neurotoxins implicated in the development of HAD is the HIV‐1 transactivating protein, Tat. To investigate the mechanism by which Tat causes neurotoxicity, brain‐derived Tat sequences from nondemented (Tat‐ND) and demented (Tat‐HAD) AIDS patients, which differed primarily in the augmenting region of Tat, were expressed in U937 monoblastoid cells and primary human macrophages. Cells expressing Tat‐HAD protein exhibited elevated matrix metalloproteinase (MMP)‐2 and ‐7 release and activation, but cells expressing Tat‐ND did not exhibit enhanced MMP expression. Conditioned media from Tat‐HAD–transfected cells caused significantly greater neuronal death (15.4 ± 4.3%) than did Tat‐ND (4.4 ± 2.1%) or nontransfected (2.1 ± 0.8%) cell‐derived conditioned media. The neurotoxicity induced by Tat‐HAD was inhibited by anti–MMP‐2 or ‐7 antibodies (p < 0.005) but not by antibodies against MMP‐9 or Tat. Similarly, scid/nod mice receiving striatal implants of Tat‐HAD–transfected cells exhibited greater neurobehavioral abnormalities and neuronal loss (p < 0.005) than did animals receiving Tat‐ND or nontransfected cells, which were reduced by treatment with the MMP inhibitor prinomastat (p < 0.005). These findings indicate that Tat causes neuronal death through an indirect mechanism that is Tat sequence dependent and involves the induction of MMPs. Ann Neurol 2001;49:230–241
Seven mycobacteriophages from distinct geographical locations were isolated, using
mc
155 as the host, and then purified and sequenced. All of the genomes are related to cluster A mycobacteriophages, ...BobSwaget and Lokk in subcluster A2; Fred313, KADY, Stagni, and StepMih in subcluster A3; and MyraDee in subcluster A18, the first phage to be assigned to that subcluster.
The Second Canadian Conference on Education was the result of several years of determined effort by representatives of organizations concerned with education. Le deuxième Conférence canadienne sur ...l'éducation a été le résultat de plusieurs années d'efforts résolus par les représentants d'organisations intéressées à l'éducation.
PDF
