Separate bisphosphatase domain of chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: the role of the C-terminal tail in modulating enzyme activity

The separate bisphosphatase domain (amino acid residues 243-468) of the chicken liver bifunctional enzyme 6-phosphofructo-2-kinase-fructose-2,6-bisphosphatase was expressed in Escherichia coli and purified to homogeneity. The fructose-2, 6-bisphosphatase activity of the separate domain was 7-fold higher than that of the native bifunctional enzyme, and exhibited substrate inhibition characteristic of the native enzyme. The inhibition of the enzymes by fructose 2,6-bisphosphate could be overcome by Pi, glycerol 3-phosphate and GTP. Deletion of 30 amino acid residues from the C-terminus of the separate domain resulted in around a 5-fold increase in the Vmax of the bisphosphatase. Also, the truncated form was more accessible to chemical modification by diethyl pyrocarbonate and N-ethylmaleimide, suggesting a more open structure than the wild-type form. In addition, the mutation of cysteine-389 to alanine increased bisphosphatase activity by 20% and the Km value for fructose 2,6-bisphosphate by 3-fold, and both the point mutation at cysteine-389 and the deletional mutation led to the predominantly insoluble expression of the enzyme. The results indicated that the C-terminal tail plays a role in modulating the enzyme activity and suggested that the difference in the C-terminal tail sequence is responsible for the difference in activity of the chicken and rat liver fructose-2,6-bisphosphatases. It is postulated that an interaction between the C-terminal tail and the active site might be present.

[Studies on the pharmacognosy of Cortex Illicii and its adulterants]

The traditional Chinese Medicine Cortex Illicii and its adulterants were studied on textual identification, botanical origin, morphological and histological characters. The TLC and UV spertra methods were established to separate and estimate Difengpin, Magnolol and beta-sitosterol in Cortex Illicii and its products.

Densitometric evaluation of markers for cholinergic transmission in rat superior olivary complex

Cholinergic transmission in the rat superior olivary complex (SOC) was assessed by densitometric measurements of labeling with several markers: acetylcholinesterase (AChE) histochemistry, choline acetyltransferase (ChAT) immunohistochemistry, and muscarinic acetylcholine receptor (M35) immunohistochemistry and N-methylscopolamine (NMS) binding autoradiography, as well as its subtype 2 (m2) immunohistochemistry. The markers which may occur in cholinergic neurons (ChAT, m2 receptor and AChE) showed dense labeling in the ventral nucleus of the trapezoid body (VNTB), in line with other evidence that it contains cholinergic neuron somata. The markers which are predominantly in cholinoceptive neurons (M35 and NMS) showed less labeling in the SOC, suggesting few muscarinic cholinergic inputs. These results are compared with those for the cochlear nucleus.

In vitro selection of packaging sites in a double-stranded RNA virus

The Saccharomyces cerevisiae double-stranded RNA virus ScVL1 recognizes a small sequence in the viral plus strand for both packaging and replication. Viral particles will bind to this viral binding sequence (VBS) with high affinity in vitro. An in vitro selection procedure has been used to optimize binding, and the sequences isolated have been analyzed for packaging and replication in vivo. The selected sequence consists of a stem with a bulged A residue topped by a loop of several bases. Four residues of the 18 bases are absolutely conserved for tight binding. These all fall in regions that appear to be single stranded. Eight more residues have preferred identities, and six of these are in the stem. The VBS is similar to the R17 bacteriophage coat protein binding site. Packaging and replication require tight binding to viral particles.

The effect of neuropeptides on vessel tone and cAMP production

The effect of VIP, PHM, PHV, PACAP-27, and PACAP-38 on vessel tone and cAMP production was investigated in rabbit ovarian arteries in vitro. The peptides (10(-7)M) induced a significant relaxation on NA-precontracted vessels and displayed similar potencies. The cAMP accumulation induced by PACAP-27 and PACAP-38 was five times higher than the cAMP content induced by VIP, PHM, and PHV. NPY (10(-7)M) markedly reversed the relaxations induced by VIP, PHM, PHV, PACAP-27, and PACAP-38 but did not at all affect the cAMP production induced by these peptides. We conclude that the relaxation induced by VIP, PHM, PHV, PACAP-27, and PACAP-38 and the contraction evoked by NPY are not solely related to the changes of cAMP contents, and that in addition to cAMP, another intracellular signal transduction pathway may be involved.

Immunolocalization of muscarinic acetylcholine subtype 2 receptors in rat cochlear nucleus

It has been suggested that cholinergic effects in the rat cochlear nucleus (CN) are mediated by muscarinic acetylcholine receptors. In this study, immunohistochemistry for muscarinic subtype 2 (m2) receptors using a monoclonal subtype-specific antibody (Levey et al. [1995] J. Comp. Neurol. 351:339-356) revealed an m2-like system in the rat CN. A prominent lamina of m2-immunoreactive fibers and puncta was located in a subgranular layer of the caudal anteroventral cochlear nucleus (AVCN) and the posteroventral cochlear nucleus (PVCN). The superficial granular layer of the rostral AVCN and the medial sheet region also contained notable immunoreactivity for m2. Some labeled somata and their processes were found in magnocellular regions of the ventral CN. A network of neurites and puncta was located in the fusiform soma and deep layers of the dorsal CN. The olivocochlear bundle and its branches to the CN were also m2 immunoreactive and possibly contributed m2-labeled fibers and terminals to the CN. Some similarities and some differences were found between this m2 receptor distribution pattern and previous results for choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and muscarinic acetylcholine receptor immunohistochemistry and binding in the CN. The results suggest that m2 receptors that are located both pre- and postsynaptically mediate many cholinergic effects in the rat CN.

Synthesis of potent cyclic hexapeptide NK-1 antagonists. Use of a minilibrary in transforming a peptidal somatostatin receptor ligand into an NK-1 receptor ligand via a polyvalent peptidomimetic

The endogenous peptides somatostatin (SRIF) and substance P comprise very different structures. Although both bind G-protein-coupled receptors, the SRIF receptors (SSTR 1-5) recognize SRIF and related peptides which retain its beta-turn such as the potent cyclic hexapeptide SRIF agonist L-363,301 (6a), but not substance P. Conversely the NK-1 receptor binds substance P but not the above ligands. In contrast, the beta-D-glucosides 1 and 2, designed to mimic the beta-turn of 6a, bind both receptors. This observation led us to attempt the conversion of 6a into the first potent, selective cyclic hexapeptide ligand for the NK-1 receptor. To this end, we combined design with a minilibrary approach. The goal was accomplished with surprising ease, leading to the NK-1 receptor antagonist 9 (IC50 2.0 +/- 0.4 nM). This demonstrates that peptidomimetics, incorporating in this case the promiscuous beta-D-glucose scaffold, can provide valuable clues about receptor similarities not revealed by their endogenous ligands. In addition, this work suggests that the use of libraries and rational design need not be mutually exclusive approaches to lead discovery.

Vascular effects and cyclic AMP production produced by VIP, PHM, PHV, PACAP-27, PACAP-38, and NPY on rabbit ovarian artery

The relationship between vessel tone and cAMP production induced by vasoactive intestinal polypeptide (VIP), peptide histidine methionine (PHM), peptide histidine valine (PHV), pituitary adenylate cyclase activating polypeptide (PACAP-27 and PACAP-38), and neuropeptide Y (NPY) was investigated in rabbit ovarian arteries in vitro. VIP, PHM, PHV, PACAP-27, and PACAP-38 added in single-dose experiments (10(-9), 10(-8), 10(-7), and 10(-6) M) induced all a significant dose-related relaxation of noradrenaline (NA)-precontracted vessels and displayed similar potencies. VIP, PHM, PHV, PACAP-27, and PACAP-38 all increased cyclic adenosine monophosphate (cAMP) accumulation. The cAMP accumulation induced by PACAP-27 and PACAP-38 was five times higher than the cAMP content induced by the other three peptides. The peptide-induced smooth muscle relaxation did not correlate to the cAMP accumulation. NPY (10(-7) M) markedly reversed the relaxations induced by VIP, PHM, PHV, PACAP-27, and PACAP-38, but did not influence the cAMP production induced by these peptides. In conclusion, the relaxation induced by VIP, PHM, PHV, PACAP-27, and PACAP-38 and the contraction induced by NPY are not solely related to the changes of cAMP contents. These findings indicate that in addition to cAMP, another intracellular signal transduction pathway may be involved in the relaxation and contraction induced by these peptides in rabbit ovarian artery.

Interference with replication of two double-stranded RNA viruses by production of N-terminal fragments of capsid polypeptides

It is possible to interfere with the replication of a number of plant RNA viruses by systemic production of viral capsid polypeptides or RNA-dependent RNA polymerases, or by production of untranslatable portions of viral plus strands or minus strands. Interference can occur by a number of mechanisms. We have discovered that the Saccharomyces cerevisiae double-stranded RNA viruses ScVL1 and ScVLa, which exist as permanent persistent infections of their host cells, can be cured very efficiently by production of N-terminal fragments of their capsid polypeptides. These totiviruses produce only two polypeptides: a capsid polypeptide (Cap) and a Cap-Pol fusion polypeptide with RNA-dependent RNA polymerase activity. Three types of interference can be detected: interference due to overproduction of both Cap and Cap-Pol, interference due to overproduction of Cap (and consequent distortion of the Cap to Cap-Pol ratio), and interference due to negative complementation by N-terminal fragments of Cap. Some N-terminal fragments of Cap appear to be incorporated into viral particles, but only in the presence of a complete Cap protein. We postulate that incorporation of N-terminal fragments of Cap results in the formation of defective particles.

[Analysis of biochemical components of seminal plasma in male workers exposed to mercury vapor]

Determinations of transferrin (Tf), fructose (Fru), citric acid (CA), zinc (Zn) and copper (Cu) levels of seminal plasma in 38 male workers exposed to mercury vapor and 18 male unexposed controls showed levels of Tf and total Fru, and sperm density adjusted Fru level of seminal plasma in workers exposed were significantly lower than those in controls, and the latter lowered gradually with increase of exposure to mercury. No significant difference of levels of CA, Zn and Cu of seminal plasma between the two groups was found. It suggests chronic exposure to mercury vapor may cause adverse effects on Sertoli's cells of spermatogenic epithelium and seminal vesicle function.

Immunohistochemistry of muscarinic acetylcholine receptors in rat cochlear nucleus

Neurons of the cochlear nucleus (CN) receive extrinsic and intrinsic cholinergic inputs, the effects of which appear to be mediated primarily by muscarinic acetylcholine receptors (mAChRs). To investigate the distribution of mAChRs and the correlation of pre- and post-synaptic cholinergic markers in CN, we used a monoclonal anti-mAChR antibody (M35) and a monoclonal antibody against choline acetyltransferase (ChAT) to perform immunohistochemistry on rat brain sections, and we also carried out histochemistry for acetylcholinesterase (AChE) activity. The density distributions of ChAT immunohistochemistry and AChE activity histochemistry agreed well with previous quantitative measurements of the activity distributions of these enzymes. A generally close correlation between densities of M35 and ChAT immunoreactivities was found across subregions of rat CN. The localizations of M35 and ChAT immunoreactivities suggest that cholinergic synapses are mostly axosomatic in ventral CN and possibly mostly axodendritic in dorsal CN. Prominent differences in density and appearance between M35 immunoreactivity and AChE activity were found in the regions of the rat CN where granule cells predominate.

Packaging in a yeast double-stranded RNA virus

The yeast virus ScV-L1 has only two genes, cap and pol, which encode the capsid polypeptide and the viral polymerase, respectively. The second gene is translated only as a cap-pol fusion protein. This fusion protein is responsible for recognition of a specific small stem and loop region of the viral plus strands, of 19 to 31 bases in length, ensuring packaging specificity. We have used a related virus, ScV-La, which has about 29% codon identity with ScV-L1 in the most conserved region of the pol gene, to map the region in pol that is responsible for packaging L1. Characterization of a number of chimeric viral proteins that recognize L1 but have the La capsid region delimits the region necessary for recognition of L1 to a 76- to 82-codon portion of pol. In addition, we show that overproduction of the La capsid polypeptide results in curing of the ScV-La virus, analogous to the production of plants resistant to RNA viruses by virtue of systemic production of viral coat protein.

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.