Low incorporation of soleus tendon: a potential diagnostic pitfall on MR imaging

Head pain is one of the main presenting symptoms of internal carotid artery (ICA) dissection, usually in association with ischemic and/or local signs such as Horner's syndrome, lower cranial nerve palsies, or tinnitus. In rare cases, head pain remains isolated and mimics other conditions. We report a patient who suffered isolated prolonged orbital pain as the only sign of intrapetrous ICA dissection. Early recognition of such unusual facial pain may be crucial in decreasing the risk of secondary cerebral or retinal ischemia.     

Identification and characterization of the RNA chaperone activity of hepatitis delta antigen peptides

In this study, we identified an activity of the hepatitis delta antigen that both modulates the cis-cleaving activities of hepatitis delta virus (HDV) genomic RNA fragments and facilitates the trans-cleavage reactions between hammerhead ribozymes and the cognate substrates of various lengths in vitro. Hepatitis delta antigen peptides exert their effect by accelerating the unfolding and refolding of RNA molecules and by promoting strand annealing and strand dissociation. In addition, the stimulatory effect of hepatitis delta antigen peptide on hammerhead catalysis is observed whether the peptide is removed or not by phenol/chloroform extraction prior to the initiation of trans-cleavage reaction. Therefore, hepatitis delta antigen peptide acts as an RNA chaperone. The RNA chaperone domain of hepatitis delta antigen overlaps with the coiled-coil domain that is rich in lysine residues. The RNA binding domains of hepatitis delta antigen previously identified are not required for the RNA chaperone activity identified herein. The RNA chaperone activity of hepatitis delta antigen may be important for the regulation of HDV replication in vivo.     

Chromatographic investigation and computer simulation of L-deprenyl metabolism

In the present study we evidenced that progesterone could directly stimulate sperm nitric oxide synthase (NOS) in capacitated mouse spermatozoa. This stimulation led to an increase in sperm prostaglandin E2 (PGE2) production and subsequent acrosomal exocytosis. However, cGMP levels were not modified during the progesterone-induced acrosome reaction under our experimental conditions. These results suggest a functional role for nitric oxide as an intracellular messenger through, at least, stimulation of PGE2 production during the acrosome reaction triggered by progesterone.     

Measurements of variable chlorophyll fluorescence using fast repetition rate techniques: defining methodology and experimental protocols

We present a methodology, called fast repetition rate (FRR) fluorescence, that measures the functional absorption cross-section (sigmaPS II) of Photosystem II (PS II), energy transfer between PS II units (p), photochemical and nonphotochemical quenching of chlorophyll fluorescence, and the kinetics of electron transfer on the acceptor side of PS II. The FRR fluorescence technique applies a sequence of subsaturating excitation pulses ('flashlets') at microsecond intervals to induce fluorescence transients. This approach is extremely flexible and allows the generation of both single-turnover (ST) and multiple-turnover (MT) flashes. Using a combination of ST and MT flashes, we investigated the effect of excitation protocols on the measured fluorescence parameters. The maximum fluorescence yield induced by an ST flash applied shortly (10 &mgr;s to 5 ms) following an MT flash increased to a level comparable to that of an MT flash, while the functional absorption cross-section decreased by about 40%. We interpret this phenomenon as evidence that an MT flash induces an increase in the fluorescence-rate constant, concomitant with a decrease in the photosynthetic-rate constant in PS II reaction centers. The simultaneous measurements of sigmaPS II, p, and the kinetics of Q-A reoxidation, which can be derived only from a combination of ST and MT flash fluorescence transients, permits robust characterization of the processes of photosynthetic energy-conversion.     

Antiovulatory antagonists of LHRH related to antide

We report 104 analogues of the potent antiovulatory antagonist of LHRH, N-Ac-D-Nal-D-Cpa-D-Pal-Ser-Lys(Nic)-D-Lys(Nic)-Leu-Ilys-Pro-D-Ala- NH2, Antide. We replaced the Nic group in Antide with other acyl substituents to modulate size, hydrophilicity or basicity of the molecule, we also replaced the Lys residues with shorter basic amino acids, and made cyclic 5/6 analogues as well as position 5 or 6 dimers. We substituted Ilys8 with other alkyl groups and acyl derivatives. When injected in 0.1% DMSO in water in a typical antiovulatory (AO) assay. Antide gives six rats ovulating out of eight (6/8) at 2 micrograms, 4/8 at 4 micrograms, and in the histamine release assay (HRA). ED50 is > 300 micrograms/ml; [Lys(N-Isobutyl)8]Antide gave 2/8 at 2 micrograms/rat; [Lys (8-Qis)5]Antide gave 1/8 at 1 microgram, and 0/8 at 2 micrograms, and in the HRA ED50. 22 micrograms/ml; [D-Lys(8-Qis)5]Antide gave 4/8 at 1 microgram and 0/8 at 2 micrograms, and in the HRA, ED50 was 27 micrograms/ml; [Lys(8-Qic)8] gave 5/8 at 1 microgram 1/8 at 2 micrograms/ [Lys(2-Pyc)6]Antide gave 3/8 at 1 microgram, and 0/8 at 2 micrograms, and in the HRA ED50 was 116 micrograms/ml; [D-Lys (2-Pyc)5]Antide gave 5/8 at 1 microgram and in the HRA, ED50 was 100- > 300 micrograms/ml; [Lys(2-Pyc)5.D-Lys(2-Pyc)6]Antide gave 2/8 at 1 microgram. The substitutions of the Nic groups of Antide at Lys5 or D-Lys6 with 8-Qis or with 2-Pyc groups seem to give highly potent antiovulatory antagonists of LHRH and constitute significant new leads to generate potent antiovulatory compounds endowed with moderate or low histamine release.