Repbase Update, a database of eukaryotic repetitive elements.

Repbase Update is a comprehensive database of repetitive elements from diverse eukaryotic organisms. Currently, it contains over 3600 annotated sequences representing different families and subfamilies of repeats, many of which are unreported anywhere else. Each sequence is accompanied by a short description and references to the original contributors. Repbase Update includes Repbase Reports, an electronic journal publishing newly discovered transposable elements, and the Transposon Pub, a web-based browser of selected chromosomal maps of transposable elements. Sequences from Repbase Update are used to screen and annotate repetitive elements using programs such as Censor and RepeatMasker. Repbase Update is available on the worldwide web at http://www.girinst.org/Repbase_Update.html.

[Use of amnion in the treatment of anterior segment diseases of the eye]. / Zastosowanie owodni w leczeniu schorzen przedniego odcinka oka.

PURPOSE: The aim of this study is to present the results of treating the anterior segment of the eye with amnion membrane transplantation (AMT). MATERIALS AND METHODS: 16 patients were treated with amnion membrane transplantation because of: pemphigoid ocularis, combustio chaemica, ulcus corneae, keratopathia bullosa, descemetocele, symblepharon, graft disease. Histopathological investigations were performed by the use of impression cytology. RESULTS: In 4 patients we obtained only temporary improvement. In 12 patients the treatment was successful with complete reepithelialization of the cornea and the conjunctiva. The impression cytology study showed an intensive regeneration of the corneal and conjunctival epithelium.

[Evaluation of the anterior chamber depth and intraocular pressure before and after the operation of cataract in glaucoma patients]. / Ocena glebokosci komory przedniej i cisnienia wewnatrzgalkowego przed i po operacji zacmy u chorych z jaskra.

The aim of the paper was to assess the effect of surgical extracapsular cataract extraction with implantation of posterior chamber lens on the normalisation of intraocular pressure in eyes with glaucoma. The relationship between the preoperative depth of the anterior chamber and the postoperative normalisation of intraocular pressure was also investigated. The study was carried out on 138 eyes with cataract and glaucoma. Simple open-angle glaucoma was found in 37 eyes (26.8%), simple closing-angle glaucoma in 67 eyes (48.6%) and glaucoma with the pseudoexfoliation syndrome in 34 eyes (24.6%). Before the operation the intraocular pressure in patients ranged from 21 to 32 mm Hg. The depth of the anterior chamber was measured by means of ultrasound method. Intraocular pressure was checked for 9 months after the operation. In patients with open-angle glaucoma the depth of the anterior chamber ranged from 3.1 to 4.0 mm, in closing-angle glaucoma from 2.4 to 3.2 mm, with glaucoma in pseudoexfoliation syndrome from 3.3 to 4.2 mm. After operation the depth of anterior chamber was from 3.7 to 4.6 mm. Nine months after the operation in 64 patients (46.3%) there was no need for giving pressure reducing drugs. The highest percentage of patients who did not require treatment (73.2%) was among eyes with closing-angle glaucoma with the smallest depth of the anterior chamber before operation. It seems that the measurement of the anterior chamber depth before the operation in patients with cataract and closing-angle glaucoma may be only the indication whether the cataract extraction with the implant of the lens is sufficient to normalize the intraocular pressure.

N(G)-nitro-L-arginine impairs the anticonvulsive action of ethosuximide against pentylenetetrazol.

N(G)-nitro-L-arginine (NNA; an inhibitor of nitric oxide synthase) in a dose of 40 mg/kg impaired the protective activity of ethosuximide against the clonic phase of pentylenetetrazol-induced seizures in mice. The ED50 value of ethosuximide was significantly increased from 108 to 158 mg/kg. NNA (40 mg/kg) was ineffective against the protective effects of diazepam, phenobarbital and valproate against pentylenetetrazol-induced seizures. NNA (40 mg/kg) did not influence the plasma levels of the antiepileptic drugs studied, so a pharmacokinetic interaction is not probable. L-Arginine (500 mg/kg) prevented the NNA-induced reduction of the anticonvulsive activity of ethosuximide. It can be concluded that nitric oxide participates in the expression of the anticonvulsive action of ethosuximide, but not that of diazepam, phenobarbital and valproate, against pentylenetetrazol-induced seizures.

Mammalian retroposons integrate at kinkable DNA sites.

Integration of retroposed RNA in mammals occurs at staggered breaks resulting from an enzyme-generated pair of nicks at opposite DNA strands, preferably within 15-16 bp. Although consensus sequences associated with the two nicks appear somewhat different from one another, both nicking sites are rich in TA, CA and TG dinucleotide steps which are known as specific DNA sites where kinks may occur under bending constraints. This suggests that during interaction with the endonucleolytic enzyme, or enzymes, DNA undergoes bending at the integration sites and kinks are formed, as initial steps in generating the nicks. Nicking at kinkable sites, particularly at TA steps, may also play a role in integration of other insertion elements.

Integration of retroposable elements in mammals: selection of target sites.

Genomic DNA fragments generated by the reverse transcription of cellular RNA are called retroposons. Because they are flanked by short repeats, mammalian retroposons are believed to integrate at staggered chromosomal breaks. Recently, a significant sequence pattern associated with the integration of Alu and ID repeats was identified (Jurka 1996). It is represented by the 5' TTAAAA consensus sequence around the 5' ends of flanking repeats of Alu, ID, as well as, of B1 and B2 retroposed elements as shown in this paper. This consensus is a potential target for enzymatic nicking which probably occurs in the complementary strand between 3' AA and the following 3' TTTT bases. The first four bases of the flanking repeats corresponding to the 3' TTTT consensus sequence show some sequence variations that may be affected by complementary base pairing between the A-rich RNA tails and the DNA target sequences prior to nicking and reverse transcription. We discuss potential evidence for such base pairing based on correlated variations in nucleotide composition of different tail and target regions.

NG-nitro-L-arginine differentially affects glutamate- or kainate-induced seizures.

The effects of nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine (NNA) on seizures induced by excitatory amino acids, bicuculline, pentylenetetrazol and pilocarpine were studied in mice. NNA (10 and 40 mg kg-1, i.p.) enhanced the susceptibility to intracerebroventricular (i.c.v.) kainate (KA) which was reflected by a decrease in its convulsant dose 50% (CD50) from 0.66 nmol to 0.38 and 0.29 nmol/mouse, respectively. Also, NNA (40 mg kg-1) increased the KA-induced mortality. Conversely, NNA (40 mg kg-1) produced an anticonvulsant effect against i.c.v. glutamate whose CD50 value was significantly elevated from 0.49 mumol to 0.84 mumol/mouse. The convulsive activity of i.c.v. N-methyl-D-aspartic acid (NDMA), alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), and trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid (trans-ACPD) was not affected by the pretreatment with NNA (40 mg kg-1). NNA (5-40 mg kg-1) also potentiated the convulsive action of systematic KA and KA-induced mortality but (up to 40 mg kg-1) remained without effect on seizures produced by bicuculline, N-methyl-D, L-aspartic acid (NMDLA), pentylenetetrazol, and pilocarpine. Only bicuculline-produced lethality was significantly enhanced. It may be concluded that the manipulation of the NO level affects differently seizures arising from a diffuse stimulation of glutamate receptors and seizures resulting from an activation of an individual subtype of these receptors. It is noteworthy that in the majority of convulsive tests used in this study, NNA exerted no modulatory effect.

CENSOR--a program for identification and elimination of repetitive elements from DNA sequences.

CENSOR is a program designed to identify and eliminate fragments of DNA sequences homologous to any chosen reference sequences, in particular to repetitive elements. CENSOR is based on two principal algorithms of Smith & Waterman (1981) [J. Mol. Biol. 147, 195] and Wilbur & Lipman (1983) [Proc. Natl. Acad. Sci. U.S.A. 80, 726]. It includes several pre-set sensitivity levels based on both biological and statistical criteria which help to distinguish between aligned pairs of homologous and non-homologous sequences. CENSOR has been implemented in C/C + + in the SUN/UNIX environment.

Identification of new medium reiteration frequency repeats in the genomes of Primates, Rodentia and Lagomorpha.

We report eleven new families of MEdium Reiteration frequency (MER) interspersed repeats in the genomes of Primates, Rodentia, and Lagomorpha. Two families of the human repeats, MER 46 and MER 47, represent non-autonomous DNA transposons. These sequences are flanked by TA target site duplications and have terminal inverted repeats (TIRs) similar to TIRs of DNA transposons. The sequences of five other families of repeats, MER41, MER48, MER50, MER51, and RMER3, resemble long terminal repeats of retroviruses. A potential involvement of some of the reported MER repeats in the regulation of transcription and genetic rearrangements is suggested. Age estimations place the origin of most MER repeats at the time of decline in MIR (Mammalian-wide Interspersed Repeats) retroposition and before the origin of the Alu family.