Meningiomas involving the anterior clinoid process.

We report a series of 34 clinoidal meningiomas treated surgically and analyse the results according to cavernous sinus involvement. Fifteen tumours extended into the cavernous sinus. Only four of these could be resected completely, and global outcome was improved or stable in 10 cases. Overall, 20 tumours had a total resection and 14 had a partial resection. Complete removal of the sphenoid wing, including the anterior clinoid and part of the planum sphenoidale, allows early devascularization of the tumour and minimizes brain retraction when associated with resection of the zygomatic arch. The most frequent postoperative complication was transient CSF leak, occurring in three patients. Two patients died postoperatively, and three suffered permanent complications. There was no recurrence after total removal, but five patients showed signs of progressive tumour growth after partial removal, treated by radiotherapy in three and by surgery in two cases. Twenty patients showed preoperative visual impairment. Outcome of vision was improved or stable in 13 (68%) and worse in six cases (32%). We suggest that progressive visual impairment should lead to aggressive surgical treatment, especially when complete resection of cavernous sinus involvement can be performed.

T-helper cell epitopes on the E-glycoprotein of dengue 2 Jamaica virus.

To identify T-helper (Th)-cell epitopes, we analyzed 25 synthetic peptides, which included most of the 495-amino-acid sequence of the envelope (E)-glycoprotein of dengue 2 virus. The peptides were analyzed in three mouse strains, BALB/c (H-2d), C57BL/6 (H-2b), and outbred NIH-Swiss, for their ability to elicit antibody or prime the Th-cell compartment following two inoculations in Freund's incomplete adjuvant. Sixteen peptides were able to elicit an antipeptide antibody response in one or more mouse strain. Eleven antipeptide serum pools were able to bind to virus in ELISA. Fifteen peptides primed one or more haplotype for an in vitro antipeptide Th-cell response as measured by blastogenesis. Th-cell activation was generally confirmed by measurable in vitro production of interleukin (IL)-2/IL-4. Nine peptides that were positive for in vitro blastogenesis, 1-2, 35, 4-6, 79, 142, 208, 06, 16, and 17, elicited virus-reactive Th-cells in vitro in H-2d mice. Two of these peptides (4-6 and 17) were able to prime virus-reactive Th-cells in H-2b mice. Nine peptides primed outbred mice in vitro for an antiviral antibody response significantly greater than that seen in animals primed with an irrelevant peptide. These results correlate with, and expand on, our previous observations based on a smaller set of synthetic peptides derived from the E-glycoprotein of Murray Valley encephalitis virus and suggest that synthetic peptides can function as E-glycoprotein Th-cell epitopes. The similarity of results between two distantly related flaviviruses suggests that E-glycoprotein Th-cell epitopes are consistent in location and activity.

Initiation and regulation mechanisms of ribosomal RNA transcription in the eukaryote Acanthamoeba castellanii.

Acanthamoeba rRNA transcription involves the binding of a transcription initiation factor (TIF) to the core promoter of rDNA to form the preinitiation complex. This complex is formed in the absence of RNA polymerase I, and persists for multiple rounds of initiation. Polymerase I next binds to form the initiation complex. This binding is DNA sequence-independent, and is directed by protein-protein contacts with TIF. DNA melting occurs in a separate step. In contrast to most prokaryotic transcription, melting occurs only following nucleotide addition and beta-gamma hydrolysis of ATP is not required as for polymerase II. Growth-dependent regulation of rRNA transcription is accomplished by modification of RNA polymerase I. The inactive form of polymerase (PolE) is unable to bind to the promoter and has altered heat stability. PolE is still active in elongation; thus, the modification affects the polymerase site involved in TIF contact. Modification of a polymerases I and III common subunit has been detected leading to the suggestion that transcription of stable RNAs of the ribosome might be co-regulated by this mechanism.