Monitoring silver diamine fluoride application with optical coherence tomography

The objective of this study was to investigate the use of optical coherence tomography (OCT) for monitoring changes in the structure of caries lesions overtime after treatment with silver diamine fluoride (SDF). Artificial caries lesions were formed on dentin bovine blocks. Each block was partitioned into 5 windows: one lesion was covered by nail varnish as control (LC), one sound window was covered with nail varnish (SC), one sound window was exposed to SDF (SCT), one lesion received 2 applications of SDF (L2), while the other lesion received one application of SDF (L1). Each window was scanned using OCT before SDF application, and every week subsequently, for 12 weeks after initial SDF treatment. Parameters such as mean intensity and the width of the peak of increased reflectivity located at the sample surface and the intensity at a depth of 180-μm were monitored. High-resolution microscopy was also used to for the analysis of selected samples. Changes in the parameters measured showed significant changes on dentin lesions after SDF application. OCT resolved structural changes after SDF application as well as changes overtime. High resolution microscopy images confirm penetration of SDF into the samples. Such changes can potentially be monitored to determine if and when re-application of SDF is needed.

A case of laboratory cross-contamination of Mycobacterium tuberculosis identified using comparative genomics

BACKGROUND

Two false-positive tuberculosis (TB) cases in Yamagata Prefecture, Japan, 2016.

OBJECTIVE

To report the effectiveness of comparative genomics of Mycobacterium tuberculosis for identification of cross-contamination cases.

DESIGN

Case report of laboratory cross-contamination.

RESULTS

Beginning with detection of an identical genotype in two M. tuberculosis strains using variable number of tandem repeat typing, we suspected M. tuberculosis cross-contamination of specimens collected in a mycobacteriology laboratory based on epidemiological investigations. This suspicion was confirmed using comparative genomics of the two M. tuberculosis strains and a strain from an epidemiologically unrelated specimen from the same batch as the two strains in the mycobacteriology laboratory. All strains had an identical genomic sequence with no single nucleotide variants.

CONCLUSION

Comparative genomics, which offers the highest discrimination power, is a potent tool for identifying laboratory cross-contamination using epidemiological investigations.

Nosocomial Mycobacterium tuberculosis transmission by brief casual contact identified using comparative genomics

This paper reports a case of nosocomial transmission of Mycobacterium tuberculosis by brief casual contact. Routine variable number tandem repeat typing in Yamagata Prefecture, Japan found that M. tuberculosis clinical isolates from two patients showed indistinguishable genotypes. The patients had an epidemiological relationship of sharing a waiting room in a hospital on the same day. As comparative genomics detected only two single nucleotide variants between the isolates, it was concluded that recent tuberculosis transmission occurred in the waiting room. These results indicate that the physical separation of infectious tuberculosis patients is an essential control measure for preventing unpredictable nosocomial transmission by casual contact.

What are Canadian primary care physicians prescribing for the treatment of gonorrhea?

BACKGROUND

Cases of Neisseria gonorrhea are on the rise in Canada, which-if undetected or undertreated-can lead to morbidity and infertility. In addition, the number of antimicrobial resistant strains is also increasing creating the risk that N. gonorrhea may become untreatable. In 2013, the Public Health Agency of Canada (PHAC) released Canadian recommendations for the management and treatment of gonorrhea that identified the need for combination therapy to address and minimize antimicrobial resistance. However, the level of awareness and uptake of these guidelines is not well-known.

OBJECTIVES

To assess primary care physicians' prescribing practices for the management and treatment of gonorrhea.

METHODS

After validity testing, two online cross-sectional surveys were conducted with a convenience sample of Canadian physicians. Physicians answered true/false statements and open-ended questions relating to three clinical scenarios: 1) suspected anogenital infection drawing from a population of men who have sex with men (MSM); 2) suspected anogenital infection drawing from a non-MSM population; and, 3) suspected pharyngeal infection drawing from any population. Frequencies of responses were calculated for the statements. Open-ended responses were recoded into treatment categories and frequencies were calculated for each scenario.

RESULTS

A total of 625 physicians completed the survey. Most physicians (60%-95%) accurately identified knowledge statements regarding pharmaceutical management, partner notification and public health reporting. For all clinical scenarios, 30%-35% of physicians did not provide any treatment information, approximately 30% indicated treating with cephalosporin monotherapy, 20%-25% indicated they would prescribe a cephalosporin and azithromycin and a minority of physicians identified other treatment options. When physicians were asked about the purpose of the second antibiotic, azithromycin, 49% indicated it was to provide presumptive treatment for gonorrhea and chlamydia. Forty-one percent indicated it was to provide presumptive treatment for chlamydia only.

CONCLUSION

This convenience sample suggests that although knowledge of pharmaceutical management, partner notification, and public health reporting is high, the use of combination therapy to deter the development of antimicrobial resistant gonorrhea may not be widespread among primary care physicians. In light of both the growing incidence of N. gonorrhea and the rising rates of antimicrobial resistance in Canada, consideration on how to improve awareness and update of best prescribing practices in primary care may be indicated.

Putative classification of clades of enterohemorrhagic Escherichia coli O157 using an IS-printing system

Enterohemorrhagic Escherichia coli O157 (O157) strains can be classified in clades by single nucleotide polymorphisms (SNPs), but this analysis requires significant laboratory effort. As the distribution of insertion sequence (IS) 629 insertions has been reported to be biased among different clades, O157 isolates can be putatively classified in clades by comparison with an IS629 distribution database. A database of the IS629 distribution in O157 strains isolated in Chiba Prefecture and their classification in clades was determined by SNP analysis and IS-printing, an easy and quick analytical tool for IS629 in the O157 genome. The IS629 distribution in O157 strains isolated in Fukuoka and Yamagata Prefectures was determined by IS-printing. These strains were putatively classified in clades by Relative Likelihood calculations that compared the IS-printing data and the IS629 distribution database. Concordance Ratios were calculated, which compared the number of strains putatively classified in a clade by Relative Likelihood to the number of strains classified in that clade by SNP analysis. For the Fukuoka and Yamagata strains, the Concordance Ratios for clades 3, 6 and 8 were 97-100%, for clade 7 about 88%, and for clades 2 and 12 over 90%. In conclusion, O157 clade 2, 3, 6, 7, 8 and 12 strains could be putatively classified by IS-printing.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrated that enterohemorrhagic E. coli O157 (O157) strains could be putatively classified in clades using an IS-printing system. IS-printing was previously developed as a relatively quick and easy tool for analysis of insertion sequence 629 in the O157 genome. Since most local government public health institutes in Japan carry out IS-printing for early detection of O157 outbreaks, these data should be useful for putative classification of O157 strains in each area.

A review of Human Immunodeficiency Virus (HIV) rapid testing

BACKGROUND

In Canada, it is estimated that 71,300 persons were living with HIV at the end of 2011. Approximately 25% (14,500 to 21,500) of prevalent cases were unaware of their HIV infection. Expanded use of HIV rapid tests may increase the detection of undiagnosed infections, enable earlier treatment and support services and prevent the onward transmission of HIV.

OBJECTIVE

To examine patient acceptability, impact (defined as receipt of test results and linkage to care) and cost-effectiveness of HIV rapid tests.

METHODS

A search was conducted for systematic reviews on HIV rapid testing, with studies from both developed and developing countries, published in English and between 2000 and 2013. The Assessment of Multiple Systematic Review (AMSTAR) tool was used to assess the included systematic reviews for methodological quality. Results were summarized narratively for each of the outcomes.

RESULTS

Eight systematic reviews were included. Acceptability of HIV rapid tests was generally high in medical settings (69% to 98%) especially among pregnant women and youth attending emergency rooms but was lower in non-medical settings (14% to 46%). The percentage of people who obtained their test results was variable. It was high (83% to 93%) in emergency rooms but was low in a rapid care setting with regular business hours (27%). Impact on linkage to care was limited. Only one systematic review examined cost-effectiveness of rapid testing and concluded that HIV rapid tests were cost-effective in comparison to traditional methods; however, results were all based on static models.

CONCLUSION

Overall, HIV rapid tests demonstrated generally high acceptability, variability in receiving test results and limited impact on linkage to care. While these findings suggest that HIV rapid tests may be useful, further research is needed to confirm in whom, when and where they are best used and how to ensure better linkage to care.

Analysis of the population genetics of clades of enterohaemorrhagic Escherichia coli O157:H7/H- isolated in three areas in Japan

AIMS

The genetic differences of enterohaemorrhagic Escherichia coli O157 (O157) strains isolated from humans in three widely-separated areas in Japan were analysed to provide information on possible geographic aspects of O157 pathogenicity.

METHODS AND RESULTS

Epidemiologically unlinked O157 strains were isolated in Chiba (300 strains), Fukuoka (260 strains) and Yamagata (81 strains) prefectures. These strains were classified in clades by single nucleotide polymorphism in seven loci and lineage-specific polymorphism assay-6, and differences between the strains in each clade were compared by population genetic analyses using the IS-printing system. Analysis of the clades from the three areas showed linkage disequilibrium of the strains in each clade. Comparison of the genetic differences of strains from the three areas in each clade, from calculated ΦPT values, indicated that the strains in each clade were the same population in all three areas, except possibly the clade 12 strains.

CONCLUSIONS

Population genetics analyses confirmed that the distribution of O157 strains in the clades isolated in three areas in Japan were similar and stable.

SIGNIFICANCE AND IMPACT OF THE STUDY

The pathogenicity of O157 strains infecting humans was comparable due to the similar, stable geographic distribution of O157 clades.

In situ multi-level analysis of viscoelastic deformation mechanisms in tendon collagen

Tendon is a hydrated multi-level fibre composite, in which time-dependent behaviour is well established. Studies indicate significant stress relaxation, considered important for optimising tissue stiffness. However, whilst this behaviour is well documented, the mechanisms associated with the response are largely unknown. This study investigates the sub-structural mechanisms occurring during stress relaxation at both the macro (fibre) and nano (fibril) levels of the tendon hierarchy. Stress relaxation followed a two-stage exponential behaviour, during which structural changes were visible at the fibre and fibril levels. Fibril relaxation and fibre sliding showed a double exponential response, while fibre sliding was clearly the largest contributor to relaxation. The amount of stress relaxation and sub-structural reorganisation increased with increasing load increments, but fibre sliding was consistently the largest contributor to stress relaxation. A simple model of tendon viscoelasticity at the fibril and fibre levels has been developed, capturing this behaviour by serially coupling a Voigt element (collagen fibril), with two Maxwell elements (non-collagenous matrix between fibrils and fibres). This multi-level analysis provides a first step towards understanding how sub-structural interactions contribute to viscoelastic behaviour. It indicates that nano- and micro-scale shearing are significant dissipative mechanisms, and the kinetics of relaxation follows a two-stage exponential decay, well fitted by serially coupled viscoelastic elements.

The fragile X mental retardation protein binds and regulates a novel class of mRNAs containing U rich target sequences

Fragile X syndrome is a common form of inherited mental retardation caused by the absence of the fragile X mental retardation protein (FMRP). It has been hypothesized that FMRP is involved in the processing and/or translation of mRNAs. Human and mouse target-mRNAs, containing purine quartets, have previously been identified. By using cDNA-SELEX (systematic evolution of ligands by exponential enrichment), we identified another class of human target-mRNAs which contain U rich sequences. This technique, in contrast to oligonucleotide-based SELEX, allows the identification of FMRP targets directly from mRNA pools. Many of the proteins encoded by the identified FMRP targets have been implicated in neuroplasticity. Steady state levels of target-mRNAs were unchanged in the brain of fragile X mice. However, levels of two target-encoded proteins, an L-type calcium channel subunit and MAP1B, were downregulated in specific brain regions suggesting a defect in the expression of target-encoded proteins in fragile X syndrome.

IGF-I-induced apoptosis in LM2d6 cultured at a low concentration of fetal bovine serum

We examined the effects of IGF-I (1-1000 ng/ml) on cell proliferation in LM2d6 mouse fibroblast cells at 0.1, 1.0 and 5.0% fetal bovine serum (FBS). In medium containing 0.1% FBS, treatment of LM2d6 cells with IGF-I significantly reduced the cell number in a dose- and time-dependent manner, whereas no effects were seen at 1 or 5% FBS. Treatment of the cells with 0.1% FBS for 72 h caused DNA laddering and nuclear condensation. However, Scatchard analysis for IGF-I binding sites on the cells revealed that both the number and the affinity of IGF-I receptors were not greater than that of Balb/3T3 cells. Furthermore, the apoptotic action of Long (R(3))-IGF-I, an analogue of IGF-I that has a reduced affinity for IGF binding proteins, was not greater than that of IGF-I. Taken together, we conclude that IGF-I reduces cell proliferation at low levels of FBS due to the induction of apoptosis. This effect is probably not caused by an excess production of IGF binding proteins in LM2d6 cells.

Avoidance responding following amphetamine-induced dopamine depletion

The effect of an amphetamine-induced depletion of striatal dopamine on active and passive avoidance responding of rats was examined. Sixteen animals received two sets of 4 injections each of 15 mg/kg d-amphetamine, administered at 2 hr intervals with each set delivered one week apart. One week after the last injection, animals were given 50 consecutive active avoidance trials in a shuttle box. Animals treated with amphetamine exhibited a 50%, depletion of striatal dopamine and showed a slower learning curve, as evidenced by significantly fewer avoidances and a slower escape latency during trials 21-30. Both groups demonstrated a 90% avoidance rate by trials 41-50. A separate group of rats was treated as above and trained for several weeks on the active avoidance procedure. Haloperidol (0.01-0.10 mg/kg intraperitoneally) dose-dependently decreased avoidance number and increased avoidance and escape latency in both groups, an effect that was exaggerated in those animals previously treated with amphetamine. Finally, these animals were tested in the same apparatus using a passive avoidance procedure. The amphetamine treatment produced a significantly higher mean number of avoidances in this procedure compared to saline-treated animals during trials 1-20. These results suggest that the impairment in conditioned avoidance following amphetamine treatment is due to a motoric, rather than a cognitive deficit.

Infection of bovine immunodeficiency virus and bovine leukemia virus in water buffalo and cattle populations in Pakistan

A survey of antibodies to bovine immunodeficiency virus (BIV) known as bovine lentivirus and bovine leukemia virus (BLV) was conducted with samples from water buffalo and cattle populations in Pakistan. A total of 370 water buffaloes and 76 cattle were tested, and 10.3% and 15.8%, respectively, were found positive for anti-BIV p26 antibodies determined by Western blotting, while 0.8% of water buffaloes and no cattle were positive for anti-BLV antibodies determined by immunodiffusion test. BIV-seropositive water buffaloes and cattle were found to have BIV proviral DNA in the peripheral blood mononuclear cells determined by nested polymerase chain reaction. This is the first report of BIV infections in water buffaloes.

Effects of NTE-122, an acyl-CoA:cholesterol acyltransferase inhibitor, on cholesterol esterification and lipid secretion from CaCo-2 cells, and cholesterol absorption in rats

The effect of NTE-122 (trans-1,4-bis[[1-cyclohexyl-3-(4-dimethylamino phenyl)ureido]methyl]cyclohexane), an acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, on cholesterol absorption was investigated. NTE-122 inhibited whole-cell ACAT activity in CaCo-2 cells, a human intestinal cell line, with an IC50 value of 4.7 nM. In CaCo-2 cells cultured on a membrane filter, NTE-122 pronouncedly inhibited the basolateral secretion of newly synthesized cholesteryl esters, and significantly reduced the basolateral secretion of newly synthesized triglycerides without influencing the cellular triglyceride synthesis. Furthermore, NTE-122 (1 mg/kg, p.o.) inhibited [14C]cholesterol absorption in rats. These results suggest that NTE-122 is capable of exhibiting anti-hyperlipidemic effects by reducing the absorption of dietary cholesterol.

Effects of NTE-122, a novel acyl-CoA:cholesterol acyltransferase inhibitor, on cholesterol esterification and secretions of apolipoprotein B-containing lipoprotein and bile acids in HepG2

We studied the effect of NTE-122 (trans-1,4-bis[[1-cyclohexyl-3-(4-dimethylamino phenyl) ureido]methyl]cyclohexane), a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, on intracellular cholesterol esterification and the secretion of apolipoprotein B100 (apoB)-containing lipoprotein and bile acids in the human hepatoma cell line HepG2. NTE-122 markably inhibited [3H]oleate incorporation into cholesteryl esters in HepG2 cells incubated with 5 microg/ml 25-hydroxycholesterol as a stimulus for ACAT (IC50=6.0 nM). On the other hand, NTE-122 did not affect [3H]oleate incorporation into triglycerides and phospholipids and [14C]acetate incorporation into cholesterol. The stimulation of ACAT by 25-hydroxycholesterol caused significant increases in the secretion of radiolabeled cholesteryl esters, radiolabeled triglycerides and apoB mass. NTE-122 pronouncedly inhibited the secretion of radiolabeled cholesteryl esters in proportion to the inhibition of cellular cholesterol esterification, and it significantly reduced the secretion of radiolabeled triglycerides and apoB mass in HepG2 cells incubated with 25-hydroxycholesterol. Furthermore, NTE-122 increased the secretion of bile acids synthesized from [14C]-cholesterol. These results suggest that NTE-122 is capable of exhibiting anti-hyperlipidemic effects by reducing both the cholesterol content and the amount of secreted very low-density lipoprotein and enhancing the excretion of bile acid from the liver.

Snapshot of a large dynamic replicon in a halophilic archaeon: megaplasmid or minichromosome?

Extremely halophilic archaea, which flourish in hypersaline environments, are known to contain a variety of large dynamic replicons. Previously, the analysis of one such replicon, pNRC100, in Halobacterium sp. strain NRC-1, showed that it undergoes high-frequency insertion sequence (IS) element-mediated insertions and deletions, as well as inversions via recombination between 39-kb-long inverted repeats (IRs). Now, the complete sequencing of pNRC100, a 191,346-bp circle, has shown the presence of 27 IS elements representing eight families. A total of 176 ORFs or likely genes of 850-bp average size were found, 39 of which were repeated within the large IRs. More than one-half of the ORFs are likely to represent novel genes that have no known homologs in the databases. Among ORFs with previously characterized homologs, three different copies of putative plasmid replication and four copies of partitioning genes were found, suggesting that pNRC100 evolved from IS element-mediated fusions of several smaller plasmids. Consistent with this idea, putative genes typically found on plasmids, including those encoding a restriction-modification system and arsenic resistance, as well as buoyant gas-filled vesicles and a two-component regulatory system, were found on pNRC100. However, additional putative genes not expected on an extrachromosomal element, such as those encoding an electron transport chain cytochrome d oxidase, DNA nucleotide synthesis enzymes thioredoxin and thioredoxin reductase, and eukaryotic-like TATA-binding protein transcription factors and a chromosomal replication initiator protein were also found. A multi-step IS element-mediated process is proposed to account for the acquisition of these chromosomal genes. The finding of essential genes on pNRC100 and its property of resistance to curing suggest that this replicon may be evolving into a new chromosome.

Complete genomic sequence and analysis of the prion protein gene region from three mammalian species

The prion protein (PrP), first identified in scrapie-infected rodents, is encoded by a single exon of a single-copy chromosomal gene. In addition to the protein-coding exon, PrP genes in mammals contain one or two 5'-noncoding exons. To learn more about the genomic organization of regions surrounding the PrP exons, we sequenced 10(5) bp of DNA from clones containing human, sheep, and mouse PrP genes isolated in cosmids or lambda phage. Our findings are as follows: (1) Although the human PrP transcript does not include the untranslated exon 2 found in its mouse and sheep counterparts, the large intron of the human PrP gene contains an exon 2-like sequence flanked by consensus splice acceptor and donor sites. (2) The mouse Prnpa but not the Prnpb allele found in 44 inbred lines contains a 6593 nucleotide retroviral genome inserted into the anticoding strand of intron 2. This intracisternal A-particle element is flanked by duplications of an AAGGCT nucleotide motif. (3) We found that the PrP gene regions contain from 40% to 57% genome-wide repetitive elements that independently increased the size of the locus in all three species by numerous mutations. The unusually long sheep PrP 3'-untranslated region contains a "fossil" 1.2-kb mariner transposable element. (4) We identified sequences in noncoding DNA that are conserved between the three species and may represent biologically functional sites.

Prevention of hydrogen peroxide damage by soybean saponins to mouse fibroblasts

Soybean saponin is one of several soybean glycosides. Recently, new soybean saponins which possess the DDMP (2,5-dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one) moiety have been detected. Soyasaponin beta g of these new soybean saponins was shown to inhibit hydrogen peroxide damage to mouse fibroblast cells. Not only the new saponin but also soyasaponin I, which has lost the DDMP moiety from soyasaponin beta g, was tested and showed higher inhibition in this assay. In order to investigate the relationship between the effect and chemical structure, glycyrrhizin, which has a similar chemical structure to soyasaponin I, was also tested and exhibited the same effect as soyasaponins beta g and I. Soyasaponin Ab, a major authentic bisdesmosidic saponin that exists only in the soybean hypocotyl, was also tested and exhibited the highest inhibition of hydrogen peroxide damage among the four saponins. It was concluded that water-soluble soybean saponins protected the cells from damage by hydrogen peroxide.

Rapid purification of fluorescent dye-labeled products in a 96-well format for high-throughput automated DNA sequencing

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DMSO resolves certain compressions and signal dropouts in fluorescent dye labeled primer-based DNA sequencing reactions

Automated base calling algorithms are more sensitive to the quality of the DNA sequencing data than are the labor intensive visual methods of base calling. To improve this quality, data from DNA sequencing reactions have been compared in order to determine the effects of the inclusion of dimethyl sulfoxide (DMSO). Inclusion of 10% DMSO into the reaction cocktail resolves at least one type of sequence compression. This compression may be due to the lack of ability in T7 DNA polymerase to read through certain sequences correctly. The poor quality of these data is seen as radioactive bands or fluorescent signal peaks that have an abnormal alignment, either in the wrong order or as single bands/peaks. The inclusion of DMSO also resolves sequences where the peak signal is absent or severely diminished, leading to a "gap" in the chromatogram profile. DMSO is better than deaza-dITP for resolving certain compressions. Addition of DMSO is a cheaper and more efficient method for high-throughput DNA sequencing than repeating reactions with base analogs.

Organization, sequence, and function of 34.5 kb of genomic DNA encompassing several murine T-cell receptor alpha/delta variable gene segments

A cosmid-bearing murine genomic DNA, encompassing several T-cell receptor variable alpha/delta gene segments, has been sequenced using shotgun DNA cloning methodology coupled with fluorescence-based high-through-put DNA sequencing technology. This region, spanning 34.5 kb, contains a pseudogene V alpha gene segment (psi V alpha 16.1), a V delta gene segment (V delta 2), and a variable gene segment that has been reported to be expressed with both C alpha (V alpha 6) and C delta (V delta 3). Therefore, this cosmid is the ideal vehicle for examining the possible control sequences that may be involved in determining whether a V gene segment associates with either C alpha or C delta. Polymerase chain reaction experiments demonstrate that the two functional variable gene segments (V delta and V alpha/delta) are expressed individually with both C alpha and C delta genes as mRNA, indicating a permissiveness in their expression patterns. In addition, a variety of genomic sequence-related features have been identified.

Intragenic and intergenic recombination between temperature-sensitive mutants of vaccinia virus

The frequency of recombination for a complete set of two-factor crosses between vaccinia virus mutations separated by distances of between 54 and 10692 bp was determined. The results show that in intragenic crosses there is a linear relationship between the recombination frequency observed and distances between the mutations of up to 700 bp. However, no length dependence of the recombination frequency in intergenic crosses with a distance between mutations of 328 to greater than 10000 bp is observed. We attribute this lack of dependence to the high rate of viral DNA interchange, which makes some step other than the cross-over event rate-limiting. Furthermore, we believe that the observed difference in recombination frequency between inter- and intragenic recombination is due to complementation between temperature-sensitive mutants at the permissive temperature.

Phosphorescent zinc sulfide is a nonradioactive alternative for marking autoradiograms

Phosphorescent zinc sulfide is a nonradioactive alternative for making orientation and identification markings on autoradiograms. Measurements with a luminometer show that light emission is linear with respect to ZnS concentration. A minimum activation time of 5 s has been determined, using an incandescent lamp as a light source. Emission decay kinetics show light emissions reached background levels within minutes, depending on the ZnS concentration. This time period is sufficient for X-ray films to be permanently marked. Because of its efficiency and nontoxicity, this autoradiogram marker could be extremely useful in many protocols, including high-throughput radioactive DNA sequencing. This nonradioactive marker will also be useful in protocols utilizing nonradioactive detection systems, such as those calling for biotinylated and chemiluminescent probes.

Superinfection exclusion of vaccinia virus in virus-infected cell cultures

Vaccinia virus-infected BSC 40 cells do not permit the replication of superinfecting vaccinia virus. The extent of superinfecting virus propagation depends on the time of superinfection; there is 90% exclusion by 4 hr after the initial infection, and more than 99% by 6 hr. When superinfection is attempted at 6 hr after infection, the superinfecting virus is incapable of carrying out DNA replication or early gene transcription, demonstrating that an early event in the virus life cycle is inhibited. The rate of adsorption of the superinfecting virus is unaltered which shows that exclusion is affected at a point between adsorption and early gene transcription. In order to exclude superinfection, the primary infecting virus does not require replication of its DNA or expression of its late genes but it must express one or more early genes.

Solid-phase synthesis of 16 potent (selective and nonselective) in vivo antagonists of oxytocin

We describe the synthesis and some pharmacological properties of 16 new in vivo antagonists of oxytocin. These are based on modifications of three peptides: A, B, and C. A is our previously reported potent and selective antagonist of the vasopressor (V1 receptor) responses to arginine-vasopressin (AVP)/weak oxytocin antagonist, [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid), 2-O-methyltyrosine]arginine-vasopressin (d(CH2)5[Tyr(Me)2]AVP. B reported here, the Ile3 analogue of A, is d(CH2)5[Tyr(Me)2]AVT (5 below) and C is our previously reported potent nonselective oxytocin antagonist/AVP V1 antagonist, [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-O- methyltyrosine,8-ornithine]vasotocin (d(CH2)5[Tyr(Me)2]OVT). The following substitutions and deletions, alone or in combination, were employed in A, B, and C: 1-deaminopenicillamine (dP); D-Tyr(Alk)2 (where Alk = Me or Et), D-Phe2; Val4, Thr4; delta 3-Pro7; Lys8, Cit8; desGly9, desGly-NH2(9), Ala-NH2(9); Leu-NH2(9); Arg-NH2(9). The 16 new analogues are (1) d(CH2)5[D-Tyr(Me)2]AVP, (2) d(CH2)5[D-Tyr(Me)2, Val4,delta 3-Pro7]AVP, (3) d(CH2)5[D-Tyr-(Et)2, Val4,Lys8]VP, (4) d(CH2)5[D-Tyr(Et)2,Val4,Cit8]VP, (5) d(CH2)5[Tyr(Me)2]AVT, (6) d(CH2)5[Tyr(Me)2,Lys8]VT, (7) dP[Tyr(Me)2]AVT, (8) dP[Tyr(Me)2,Val4]AVT, (9) d(CH2)5[D-Tyr(Me)2, Val4]AVT, (10) d(CH2)5[D-Phe2,Val4]AVT, (11) d(CH2)5[Tyr(Me)2,Thr4]OVT, (12) d(CH2)5[Tyr(Me)2,Thr4,Ala-NH2(9)]OVT, (13) d(CH2)5[Tyr(Me)2,Thr4,Leu-NH2(9)]OVT, (14) d(CH2)5[Tyr(Me)2,Thr4,Arg-NH2(9)]OVT, (15) desGly-NH2(9),d(CH2)5[Tyr(Me)2,Thr4]OVT, (16) desGly9,d(CH2)5[Tyr(Me)2,Thr4]OVT. 1-4 are analogues of A, 5-10 are analogues of B, and 11-16 are analogues of C. Their protected precursors were synthesized either entirely by the solid-phase method or by a combination of solid-phase and solution methods (1 + 8 or 8 + 1 couplings). All analogues were tested in rats for agonistic and antagonistic activities in oxytocic (in vitro, without and with Mg2+, and in vivo) assays as well as by antidiuretic and vasopressor assays. All analogues exhibit potent oxytocic antagonism in vitro and in vivo. With an in vitro pA2 (in the absence of Mg2+) = 9.12 +/- 0.09, dP[Tyr(Me)2]AVT is (7) one of the most potent in vitro oxytocin antagonists reported to date. Fifteen of these analogues (all but 6) appear as potent or more potent in vivo oxytocin antagonists than C (pA2 = 7.37 +/- 0.17). Analogues 1-9 and 14 are potent AVP V1 antagonists. Their anti-V1 pA2 values range from 7.92 to 8.45. They are thus nonselective oxytocin antagonists.(ABSTRACT TRUNCATED AT 400 WORDS)

2-O-alkyltyrosine derivatives of 1-deamino-arginine-vasopressin: highly specific and potent antidiuretic agonists

We report the solid-phase synthesis of eight 2-O-alkyltyrosine analogues of 1-deamino-arginine-vasopressin (dAVP) with enhanced antidiuretic agonistic specificity. These peptides are as follows: 1-deamino[2-O-methyltyrosine]-arginine-vasopressin (dTyr(Me)AVP), 1-deamino[2-O-ethyltyrosine]arginine-vasopressin (dTyr(Et)AVP), 1-deamino[2-O-methyltyrosine,8-D-arginine]vasopressin (dTyr(Me)DAVP), 1-deamino[2-O-ethyltyrosine,8-D-arginine]vasopressin (dTyr(Et)DAVP), 1-deamino[2-O-methyltyrosine,4-valine]arginine-vasopressin (dTyr(Me)VAVP), 1-deamino[2-O-ethyltyrosine,4-valine]arginine-vasopressin (dTyr(Et)VAVP), 1-deamino[2-O-methyltyrosine,4-valine,8-D-arginine]vasopressin (dTyr(Me)VDAVP), and 1-deamino[2-O-ethyltyrosine,4-valine,8-D-arginine]vasopressin (dTyr(Et)VDAVP). All analogues were tested for antidiuretic, antivasopressor, and antioxytocic activities. Deamination, as was expected, significantly enhanced the antidiuretic properties of these analogues relative to their parent N-amino-O-alkyltyrosine peptides. With the exception of dTyr(Me)AVP, all of these analogues are antagonists of the vasopressor responses to AVP and of the uterine response to oxytocin. Thus they all exhibit high antidiuretic agonistic specificity. Due to its remarkable properties, dTyr(Me)VDAVP is a unique compound in this series. It appears to be the most potent antidiuretic agonist (1740 units/mg) and also a vasopressor antagonist and a potent oxytocin antagonist. It is thus a highly specific antidiuretic agonist. In general, all of these new analogues are highly specific and thus are potentially useful as pharmacological tools and clinical agents.

Vaccinia virus gene D8 encodes a virion transmembrane protein

Transcription mapping studies and DNA sequence analysis of the vaccinia virus HindIII D fragment predict that gene D8 encodes a protein 304 amino acids in length, with a molecular mass of 35,426 daltons, that is expressed at late times in infection. In order to determine whether the native D8 protein is required for virus propagation, we constructed a frameshift mutation in the D8 coding sequence. Virus containing this mutation were isolated and shown to replicate in a single-step growth experiment with wild type virus growth kinetics, demonstrating that the normal-length D8 protein is not essential for virus propagation in tissue culture. In order to investigate the synthesis of the wild-type and the mutant D8 proteins in virus-infected cells, we raised polyclonal antisera to a fusion protein consisting of a portion of the D8 coding sequence linked to the Escherichia coli trpE gene. Western blot (immunoblot) analysis of the time course of D8 protein synthesis in cells infected with either wild-type or mutant virus demonstrated that D8 protein was synthesized late in infection in each case and accumulated throughout the experiment. To determine whether the D8 protein was incorporated into the mutant or wild-type virus, purified virions were fractionated into Nonidet P-40-soluble, deoxycholate-soluble, and detergent-insoluble fractions. In both the wild-type and the mutant viruses, the D8 protein was an integral viral protein. The wild-type protein partitioned into the Nonidet P-40-soluble fraction, suggesting that it was a viral membrane protein. The mutant protein fractionated into the detergent-insoluble component, demonstrating that although the altered protein was incorporated into the virus, it was found in a abnormal location. In order to determine whether the D8 protein was present on the virion surface, the susceptibility of the D8 protein to proteolysis was tested by analyzing the products of incubation of the wild-type and mutant viruses with either chymotrypsin or trypsin. These studies demonstrated that the wild-type D8 protein was a transmembrane protein with a major extraviral domain that was released largely intact from the virus by trypsin. The mutant D8 protein was relatively refractory to proteolysis, confirming the hypothesis that although it is associated with the virus, it is in a conformation different from that of the wild-type protein. Tryptic digestion of the wild-type virus increased plaque formation severalfold, concomitant with the removal of the extraviral domain of the D8 protein.(ABSTRACT TRUNCATED AT 400 WORDS)

C-terminal deletions in agonistic and antagonistic analogues of vasopressin that improve their specificities for antidiuretic (V2) and vasopressor (V1) receptors

We report the solid-phase synthesis of 12 desGly and 12 desGly(NH2) analogues of arginine-vasopressin (AVP), two highly selective antidiuretic (V2) agonists, four vasopressor (V1) antagonists, and five V2/V1 antagonists. The parent AVP agonists are (1) AVP, (2) 1-deamino[8-D-arginine]vasopressin (dDAVP), and (3) its 4-valine analogue, dVDAVP. The parent V1 antagonists are (4) [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid)] arginine-vasopressin (d(CH2)5AVP), (5) d(CH2)5VDAVP, (6) [1-deaminopenicillamine,4-valine,8-D-arginine]vasopressin (dPVDAVP), and (7) d(CH2)5[Tyr(Me)]AVP. The parent V2/V1 antagonists are (8) d(CH2)5[D-Phe2,Ile4]AVP, (9) d(CH2)5[D-Phe2]VAVP, (10) d(CH2)5[D-Tyr(Et)2]VAVP, (11) d(CH2)5[Tyr(Et2]VAVP, and (12) d(CH2)5[D-Ile2,Ile4]AVP. All 24 analogues were tested for agonistic and antagonistic activities in in vivo rat vasopressor and rat antidiuretic assays. The desGly and desGly(NH2) analogues of 1-3 are either weak partial agonists or weak antagonists of the V1 responses to AVP. Except for desGly(NH2)AVP, which is a weak V2 agonist, the remaining desGly and desGly(NH2) analogues of 1-3 exhibit substantial V2 agonism and are thus highly selective V2 agonists. With antidiuretic activity of 321 units/mg, a resynthesized desGly(NH2)dVDAVP is equipotent with AVP as a V2 agonist. Thus our previously stated conclusion about the need for C-terminal CONH2 for V2 agonism is no longer valid. The four pairs of desGly/desGly(NH2) analogues of the V1 antagonists (4-7) all retained varying degrees of V1 antagonism and some exhibited striking enhancements in anti-V1/V2 selectivity. Thus the desGly/desGly(NH2) analogues of d(CH2)5Tyr(Me)AVP are highly potent V1 antagonists/weak V2 antagonists with anti-V1/V2 selectivities of 200 and 1200, respectively. The four pairs of desGly/desGly(NH2) analogues of the V2/V1 antagonists (8-11) exhibited enhancements, full retention, or slight diminishment of both V1 and V2 antagonism, with the desGly analogue being usually the more potent of each pair. The desGly and desGly(NH2) analogues of d(CH2)5[D-Ile2,Ile4]AVP (12) exhibited anti-V2/V1 selectivities of 46 and about 440, respectively. These are the most selective V2 antagonists reported to date. Many of these analogues could serve as useful pharmacological tools in studies on the roles of AVP in normal and pathophysiological circumstances.

Genetic map of the vaccinia virus HindIII D Fragment

Seventeen ts mutants of vaccinia virus known to map to the viral HindIII D fragment (R. C. Condit and A. Motyczka, 1981, Virology 113, 224-241; R. C. Condit, A. Motyczka, and G. Spizz, 1983, Virology 128, 429-443; M. J. Ensinger and M. Rovinsky, 1983, J. Virol. 48, 419-428) have been sorted into seven complementation groups. The precise location of each mutant on the HindIII D DNA fragment has been identified by either one-step or two-step marker rescue. By a comparison of this genetic map and the known sequence of this DNA fragment (E. G. Niles et al., 1986, Virology 153, 96-112; S. L. Weinrich and D. E. Hruby, 1986, Nucleic Acids Res. 14, 3003-3016), each mutant has been assigned to a single gene in the HindIII D fragment. In several cases, the map position of a mutant has been localized to a region of fewer than 300 bp in length. The complementation groups are evenly distributed along the DNA. However, within a single gene, the mutants are often clustered.

Nucleotide sequence and genetic map of the 16-kb vaccinia virus HindIII D fragment

We have determined the nucleotide sequence of the 16,059-bp HindIII D fragment from vaccinia virus strain WR. Translation in all 6 reading frames reveals a set of 22 open reading frames (ORFs), which are capable of encoding proteins ranging from 61 to 844 amino acids in length. With one exception, ORF 12, we have divided them into two primary sets according to their size. The minor group contains eight members ranging in length from 61 to 84 amino acids. The major group has thirteen members varying from 146 to 844 amino acids in length, and, in addition, due to its location on the DNA, one small ORF, 61 amino acids long. The neighboring major ORFs are closely packed along the DNA, being separated by 42 or fewer base pairs. In several instances the ends of adjoining ORFs overlap for up to 11 triplet codons. In three cases, 1 or 2 bases are shared between translation start and stop signals in adjacent ORFs. Regions of both strands of the DNA are transcribed. Two sets of temperature-sensitive mutations, totaling 17, which map to the HindIII D fragment, have been combined into eight complementation groups. The results of marker rescue analysis map one or more member of each group to a site in the HindIII D fragment within a defined open reading frame.

Synthesis and some pharmacological properties of 18 potent O-alkyltyrosine-substituted antagonists of the vasopressor responses to arginine-vasopressin

Using the Merrifield solid-phase method, we have synthesized 18 new 2-O-alkyltyrosine-substituted analogues (where alkyl = methyl and ethyl) of the arginine-vasopressin (AVP) vasopressor antagonists [1-deaminopenicillamine]-arginine-vasopressin (dPAVP), [1-(beta-mercapto-beta,beta-diethylpropionic acid)]arginine-vasopressin (dEt2AVP), and [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid)]arginine-vasopressin (d(CH2)5AVP) and of their 8-D-arginine (d(R2)DAVP) analogues, their 4-valine (dR2VAVP) analogues, and their 4-valine,8-D-arginine (d(R2)VDAVP) analogues [where R = CH3 or C2H5 and 2R = (CH2)5]. These analogues were tested for agonistic and antagonistic activities in in vivo rat vasopressor and rat antidiuretic and in vitro rat uterus assay systems. Although many exhibit very low antidiuretic activities, none of the new analogues antagonize antidiuretic responses to AVP. They exhibit no evident pressor activities and are in fact all highly effective antagonists of the vasopressor responses to AVP. They are also potent antagonists of the in vitro oxytocic responses to oxytocin, both in the absence and in the presence of Mg2+. These analogues together with their corresponding antivasopressor pA2 values are as follows: 1. dPTyr(Et)AVP, 8.40 +/- 0.08; 2. dEt2Tyr(Me)AVP, 8.53 +/- 0.06; 3. dEt2Tyr(Et)AVP, 8.46 +/- 0.08; 4. d(CH2)5Tyr(Et)AVP, 8.47 +/- 0.04; 5. dPTyr(Me)DAVP, 8.31 +/- 0.08; 6. dPTyr(Et)DAVP, 8.27 +/- 0.06; 7. dEt2Tyr(Me)DAVP, 8.57 +/- 0.03; 8. dEt2Tyr(Et)DAVP, 8.33 +/- 0.06; 9. d(CH2)5Tyr(Me)DAVP, 8.41 +/- 0.05; 10. d(CH2)5Tyr(Et)DAVP, 8.45 +/- 0.05; 11. dPTyr(Me)VAVP, 8.36 +/- 0.07; 12. dPTyr(Et)VAVP, 8.07 +/- 0.13; 13. dEt2Tyr(Me)VAVP, 8.29 +/- 0.08; 14. dEt2Tyr(Et)VAVP, 8.42 +/- 0.06; 15. dPTyr(Me)VDAVP, 7.84 +/- 0.06; 16. dPTyr(Et)VDAVP, 8.46 +/- 0.03; 17. dET2Tyr(Me)VDAVP, 8.35 +/- 0.10; 18. dEt2Tyr (Et)VDAVP, 8.19 +/- 0.07. Seven of these analogues are clearly more potent vasopressor antagonists than their respective unalkylated tyrosine-containing parents. In the remaining 11, antagonistic potency was not changed significantly. In no instance did 2-O-alkyltyrosine substitution decrease antagonistic potency. With pA2 values equal to or greater than 8.40, nine of these antagonists (numbers 1-4, 7, 9, 10, 14, and 16) are among the most potent vasopressor antagonists reported to date. They could thus serve as additional valuable pharmacological tools in studies on the roles of AVP in the control of blood pressure in normal and in pathophysiological conditions. These findings may also provide useful clues to the design of more potent and selective antagonists of AVP.

Phosphate uptake by primary renal proximal tubule cell cultures grown in hormonally defined medium

The uptake of labeled inorganic phosphate into primary rabbit kidney proximal tubule cells has been examined. Phosphate was accumulated into the primary proximal tubule cells against a concentration gradient. This accumulation was sensitive to inhibition by metabolic inhibitors. The dependence of phosphate uptake on the extracellular phosphate concentration was examined. Similarities were observed between primary proximal tubule cells and the LLC-PK1 cell line in these regards. These phosphate uptake data were then plotted on a Lineweaver-Burke plot. A nonlinear plot was obtained, which suggested that phosphate uptake occurs by means of a Na+ dependent, carrier mediated process, as well as by another Na+ independent mechanism. The pH dependence of phosphate uptake was also examined. Unlike previous observations with LLC-PK1 cells, optimal phosphate uptake occurred at pH 6.5. However, this difference between the two cell culture systems may possibly be explained by differences in uptake conditions. The dependence of phosphate uptake on the extracellular NaCl concentration was examined at three different pH values. The rate of phosphate uptake at pH 7.0 was observed to saturate at a lower NaCl concentration than at either pH 6.0 or pH 6.5. Furthermore, the optimal rate of phosphate uptake at pH 7.0 was observed to be higher than at the other two pH values studied when the NaCl concentration was below 120 mM. However, when the NaCl concentration was raised to 150 mM, optimal phosphate was observed to occur at pH 6.5 rather than at pH 7.0. These observations may be explained if the pH affects not only the rate of phosphate uptake but also the affinity of the phosphate uptake system for sodium. Phosphate uptake was also observed to be sensitive to several agents, Na2 X SO4 and NaSCN, which affect the membrane potential. As observed with phosphate uptake by LLC-PK1 (and renal brush border membrane vesicles), phosphate uptake was highly sensitive to inhibition by the phosphate analogue arsenate. Novel observations were that the phosphate analogue vanadate and its cellular metabolite vanadyl stimulated the initial rate of phosphate uptake.

Carboxy terminus of vasopressin required for activity but not binding

Vasopressin antagonists are valuable pharmacological tools for investigating physiological and behavioural functions of the nonapeptide arginine-vasopressin (AVP). The removal of glycinamide from the carboxy terminus of AVP drastically reduces its characteristic vasopressor and antidiuretic activities. In contrast to this we show here that removal of the carboxy-terminal glycinamide or the glycine at position 9 from several vasopressin antagonists makes little difference to their ability to block vasopressor and antidiuretic responses to AVP. These data demonstrate the critical structural requirements of the carboxy-terminal position for receptor activation, in contrast to the lack of such requirements for receptor binding. They also provide an avenue to a wide variety of antagonists substituted at the carboxy terminus (for example radiolabelled derivatives and affinity ligands) and suggest clues for the development of more potent and/or selective antagonists.

Potent and selective antagonists of the antidiuretic responses to arginine-vasopressin based on modifications of [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-D-isoleucine,4- valine]arginine-vasopressin at position 4

As part of a program in which we are attempting (a) to obtain more potent and/or more selective antagonists of the antidiuretic responses to arginine-vasopressin (AVP) and (b) to delineate the structural features at positions 1-9 required for antidiuretic antagonism, we have synthesized 13 new analogues of the antidiuretic antagonist [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-D-isoleucine,4- valine]arginine-vasopressin [d(CH2)5[D-Ile2]VAVP] in which the valine residue at position 4 has been replaced by the L-amino acids Abu, Ile, Thr, Ala, Ser, Nva, Gln, Leu, Lys, Cha, Asn, Orn, and Phe and two new analogues of the antidiuretic antagonist [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-D-phenylalanine,4- valine]arginine-vasopressin [d(CH2)5[D-Phe2]VAVP] with the Val4 residue replaced by Ser and Orn. These analogues are 1, d(CH2)5[D-Ile2,Abu4]AVP; 2, d(CH2)5[D-Ile2,Ile4]AVP; 3, d(CH2)5[D-Ile2,Thr4]AVP; 4, d(CH2)5[D-Ile2,Ala4]AVP; 5, d(CH2)5[D-Ile2,Ser4]AVP; 6, d(CH2)5[D-Ile2,Nva4]AVP; 7, d(CH2)5[D-Ile2]AVP; 8, d(CH2)5[D-Ile2,Leu4]AVP; 9, d(CH2)5[D-Ile2,Lys4]AVP; 10, d(CH2)5[D-Ile2,Cha4]AVP; 11, d(CH2)5[D-Ile2,Asn4]AVP; 12, d(CH2)5[D-Ile2,Orn4]AVP; 13, d(CH2)5[D-Ile2,Phe4]AVP; 14, d(CH2)5[D-Phe2,Ser4]AVP; and 15, d(CH2)5[D-Phe2,Orn4]AVP. The protected peptide precursors for these peptides were prepared by the solid-phase method, followed by ammonolytic cleavage. The free peptides 1-15 were obtained by deblocking with Na in NH3, oxidation of the resultant disulfhydryl compounds with dilute K3[Fe(CN)6], and purification on Sephadex G-15 in a two-step procedure with 50% HOAc and 0.2 M HOAc as eluants. Analogues 1-15 were tested in rats for agonistic and antagonistic activities by antidiuretic, vasopressor, and oxytocic assays.(ABSTRACT TRUNCATED AT 250 WORDS)

Potent antagonists of the antidiuretic responses to arginine-vasopressin based on modifications of [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-D- phenylalanine,4-valine]arginine-vasopressin at position 4

As part of a program in which we are attempting (a) to delineate the structural features at positions 1-9 in our previously reported antidiuretic antagonists required for antidiuretic antagonism and (b) to obtain analogues with enhanced antiantidiuretic potency and/or selectivity, we have synthesized 14 new analogues of the antidiuretic antagonist [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid),2-D-phenylalanine,4-valine]arginine-vasopressin [d-(CH2)5-D-Phe2VAVP), in which the valine residue at position 4 was replaced by the following L-amino acids and glycine: Ile, Abu, Thr, Ala, Gln, Lys, Cha, Nle, Nva, Phe, Leu, Gly, Tyr, and Pro. These analogues are 1, d-(CH2)5-D-Phe2,Ile4AVP; 2, d(CH2)5-D-Phe2,Abu4AVP; 3, d(CH2)5-D-Phe2,Thr4AVP; 4, d(CH2)5-D-Phe2,Ala4AVP;5, d(CH2)5-D-Phe2AVP; 6, d(CH2)5-D-Phe2,Lys4AVP; 7, d(CH2)5-D-Phe2,Cha4AVP; 8, d(CH2)5-D-Phe2,Nle4AVP; 9, d(CH2)5-D-Phe2,Nva4AVP; 10, d(CH2)5-D-Phe2,Phe4AVP; 11, d(CH2)5-D-Phe2,Leu4AVP; 12, d(CH2)5-D-Phe2,Gly4AVP; 13, d(CH2)5-D-Phe2,Tyr4AVP; 14, d(CH2)5-D-Phe2,Pro4AVP. The protected intermediates required for the synthesis of all of these peptides were prepared by the solid-phase method and cleaved from the resin by ammonolysis. Following deblocking with Na in NH3 and oxidizing with K3[Fe(CN)6], each peptide was purified on Sephadex G-15 in a two-step procedure using 50% HOAc and 0.2 M HOAc as eluants. Analogues 1-14 were tested for agonistic and antagonistic activities by antidiuretic, vasopressor, and oxytocic assays in rats. Analogues 1, 2, and 4-6 exhibit no detectable antidiuretic agonistic activity. All analogues, with the exception of the Pro4-containing analogue, are antidiuretic antagonists. Their antiantidiuretic pA2 values are as follows: 1, 8.24 +/- 0.08; 2, 7.96 +/- 0.07; 3, 7.62 +/- 0.09; 4, 7.52 +/- 0.03; 5, 7.21 +/- 0.07; 6, 7.22 +/- 0.12; 7, 7.19 +/- 0.08; 8, 7.12 +/- 0.09; 9, 6.99 +/- 0.06; 10, 6.07 +/- 0.11; 11, 6.07 +/- 0.11; 12, 5.85 +/- 0.05; 13, approximately 5.57; 14, a weak agonist (0.004 U/mg). Analogues 1-14 also antagonize the vascular responses to arginine-vasopressin (AVP) and the in vitro oxytocic responses to oxytocin. Analogues 1, 2, 3, and 5 have also been shown to antagonize the in vivo oxytocic responses to oxytocin. Five of these analogues (1, 2, 3, 6, and 7) exhibit enhanced antiantidiuretic/antivasopressor selectivity. d(CH2)5-D-Phe2,Lys4AVP and other position-4 analogues with side-chain functional groups may be useful covalent ligands with which to probe the structural characteristics of AVP renal and vascular receptors. With an antiantidiuretic "effective dose" of 0.46 +/- 0.07 nmol/kg and a pA2 value of 8.24 +/- 0.08, d(CH2)5-D-Phe2,Ile4AVP (1) appears to be the most potent antidiuretic antagonist reported to date.(ABSTRACT TRUNCATED AT 400 WORDS)

Design of more potent antagonists of the antidiuretic responses to arginine-vasopressin

As part of a program aimed at designing more potent and selective antagonists of the antidiuretic responses to arginine-vasopressin (AVP), we substituted O-alkyl-D-tyrosine (where alkyl = methyl, ethyl, isopropyl, or n-propyl) at position 2 in our eight previously reported O-alkyl-L-tyrosine antagonists of antidiuretic and vasopressor responses to AVP. We also substituted D-tyrosine for L-tyrosine in two vasopressor antagonists with weak antidiuretic agonistic activity, [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid),4-valine,8-D-arginine]vasopressin [d(CH2)5VDAVP] and its L-arginine isomer [d(CH2)5VAVP]. The ten analogues, synthesized by the solid-phase method, are as follows: 1, d(CH2)5-D-Tyr(Me)VDAVP; 2, d(CH2)5-D-Tyr(Et)VDAVP; 3, d(CH2)5-D-Tyr(i-Pr)VDAVP; 4, d(CH2)5-D-Tyr(n-Pr)VDAVP; 5, d(CH2)5-D-Tyr(Me)VAVP; 6, d(CH2)5-D-Tyr(Et)VAVP; 7, d(CH2)5-D-Tyr(n-Pr)VAVP; 8, d-(CH2)5-D-Tyr(i-PR)VAVP; 9, d(CH2)5-D-TyrVDAVP; 10, d(CH2)5-D-TyrVAVP. These analogues were tested for agonistic and antagonistic activities in rat antidiuretic and rat vasopressor systems. All ten D-tyrosine analogues possess transient weak antidiuretic activities (0.004--0.05 U/mg). Subsequent doses of AVP are reversibly antagonized for 1--3 h, depending on the dose of the antagonist. They exhibit the following antiantidiuretic pA2 values: 1, 7.19 +/- 0.11; 2, 7.59 +/- 0.04; 3, 7.51 +/- 0.06; 4, 7.60 +/- 0.05; 5, 7.77 +/- 0.07; 6, 7.81 +/- 0.07; 7, 7.66 +/- 0.11; 8, 7.61 +/- 0.06; 9, 7.03 +/- 0.05; 10, 7.51 +/- 0.08. They are all effective antagonists of vasopressor responses to AVP. Analogues 1--8 are two to ten times more potent than their respective O-alkyl-L-tyrosine isomers as antidiuretic antagonists. Since the vasopressor potencies of the O-alkyl-L-tyrosine analogues have either diminished or remained virtually unchanged, these analogues exhibit a selective increase in their antiantidiuretic/antivasopressor ratios with respect to their respective O-alkyl-L-tyrosine analogues. The finding that the substitution of an unalkylated D-tyrosine for L-tyrosine in d(CH2)5VDAVP and d(CH2)5VAVP converts these weak antidiuretic agonists into potent antagonists of antidiuretic responses to AVP is highly significant, especially in view of the relative ease of synthesis and much higher yields of unalkylated vs. alkylated tyrosine analogues. These ten new analogues are potentially useful as pharmacological tools and as therapeutic agents. The findings presented here have also obvious potential for the design of even more potent and selective antidiuretic antagonists.