IS204: an insertion sequence from Nocardia asteroides (mexicana) YP21

An insertion sequence was found in Nocardia asteroides YP21. The element, designated IS204, is 1452 bp long and has 19/23 bp imperfect inverted repeats at its ends. The sequences of IS204 terminal inverted repeats have high homology with those of IS1096 from Mycobacterium smegmatis. An 8-bp duplication of target sequence was found at the insertion site. Sequence analysis revealed that IS204 contains an open reading frame of 1134 bp, which encodes a putative transposase similar to those found in IS1096 and in Tn4652 from Pseudomonas sp. EST1001. At least nine copies of IS204 are present in the genome of N asteroides YP21. The plasmid pCY 104::IS204 could be inserted with another copy of IS204 at a different site. The possible mechanisms are discussed.

[Transurethral laser prostatectomy: report of 200 cases]

From August 1988 to May 1993, 200 patients with benign prostatic hyperplasia (BPH) were treated by transurethral laser prostatectomy (TULP) in our hospital. 165 patients were followed up for 6 months to 4.5 years and the results showed excellent effect in 128 cases, improved 32 cases, the total effectiveness was 97%. TULP, a safe and effective therapy for BPH, have more wide operative indication range but it is not suitable for patients with carcinoma of prostate.

Cloning and sequence analysis of a recA-like gene from Streptomyces venezuelae ISP5230

When genomic DNA fragments from Streptomyces venezuelae ISP5230 were probed at moderate stringency with recA from Mycobacterium tuberculosis, a 2.0-kb SmaI fragment was identified. The fragment was isolated by cloning a BamHI digest of S. venezuelae DNA in pHJL400 and screening the plasmids in Escherichia coli by Southern hybridization using a sib-selection technique. Sequencing the hybridizing region located an open reading frame encoding 377 amino acids. Its deduced amino acid sequence resembled that of recA genes from other bacteria. The cloned S. venezuelae gene conferred partial resistance to ethyl methanesulfonate when expressed in E. coli from the lacZ promoter.

Design and synthesis of sulfur-free cyclic hexapeptides which contain the RGD sequence and bind to the fibrinogen GP IIb/IIIa receptor. A conformation-based correlation between propensity for imide formation and receptor affinity

The Arg-Gly-Asp (RGD) sequence is the key recognition site in many adhesive interactions. To probe the structural and conformational requirements for potential antithrombotic agents, we have designed and synthesized three cyclic hexapeptides (1, 5 and 6) containing the RGD sequence. In the ELISA GP IIb/IIIa-fibrinogen receptor assay, 1, 5 and 6 bound with IC50 values of 1, 0.1 and 0.016 microM, respectively. All three peptides completely displaced fibrinogen from the receptor. No potent, sulfur-free cyclic hexapeptide had heretofore been described as a fibrinogen receptor antagonist. The enhanced binding affinity of 6, distinguished by the presence of two D-amino acids, is likely to reflect an increased conformational resemblance to the natural peptide ligands. Cyclization of H-Asp(OFm)-DSer-Phe-DPhe-Arg-Gly-OH with DPPA and NaHCO3 in DMF to afford 6 was attended by subsequent aspartimide formation with generation of 9-fluorenylmethanol. Interestingly, imide formation was not observed with any of the three linear hexapeptides (3, 8 and 9), with the all-L-cyclic peptide 1, nor with 5, which contains only Ser-1 in the D-configuration. The observed imide formation led us to use catalytic transfer hydrogenation rather than piperidine to remove the 9-fluorenylmethyl ester protecting group at the beta-carbonyl of aspartic acid. Further investigation revealed that imide formation was minimized by careful exclusion of water, reducing dissolution of NaHCO3. Thus the distinguishing conformational features of 6 express themselves both in receptor affinity and chemical propensity toward imide formation.

Choline acetyltransferase in cochlear root neurons

Cochlear root neurons are a distinct group of cells located in the auditory nerve root in small rodents. Their transmitter is still unknown. Some of our preparations showed immunoreactivity of somata of cochlear root neurons with both polyclonal and monoclonal antibodies against choline acetyltransferase (ChAT) which, despite their very weak histochemical reaction for acetylcholinesterase (AChE), suggested that cochlear root neurons might be cholinergic. To test this, we used a radiometric assay to measure ChAT activities of rat auditory nerve root samples containing cochlear root neurons and of adjacent samples not containing them. There was no significant difference between the low mean ChAT activities of these two groups of samples. Thus, cochlear root neurons are not likely to be cholinergic.

Variation of corneal thickness with age in young New Zealanders

The central thickness of the left eyes of 1082 New Zealand students aged 5 to 20 years were measured using optical pachometry. No significant variation in corneal thickness was found with increasing age. The mean corneal thickness of the left eye was 540 +/- 25 microns. No significant differences in corneal thickness were found when the effects of sex or cultural groupings were examined. Corneal thickness appears to remain constant between the age of 5 and 20 years, irrespective of sex or cultural grouping.

[The experimental studies of the effect of Forskolin on the lowering of intraocular pressure]

The effect of the domestic Forskolin on lowering the intraocular pressure (IOP) of rabbits was studied. The results showed that the Forskolin significantly lowered the normal IOP of rabbits and blocked the ocular hypertension induced by water load in rabbits (p < 0.01). The maximum decrease value of 2%, 1% and 0.5% of the Forskolin was 0.59. 0.36 and 0.19 kPa (1 kPa = 7.5 mmHg), which showed the noticeable dose-effect relationship. Topical ocular application of Forskolin lowered IOP in 1/2 hour, reached to a peak in 2-3 hours and remained significantly for 10 hours. The pupillary diameter did not change when IOP were reduced. Furthermore, the Forskolin had potent stimulative properties to adenylate cyclase (AC). The greater the ability of the Forskolin to stimulate AC, the stronger the effect of IOP lowering.