Human RFamide-related peptide-1 diminishes cellular and integrated cardiac contractile performance

Peptides influence cardiac dysfunction; however, peptidergic modulation of contractile performance remains relatively uncharacterized. We identified a novel human peptide that modulates mammalian contractile performance. Members of the FMRFamide-related peptide (FaRP) family contain a C-terminal RFamide but structurally variant N-terminal extension. We report human RFamide-related peptide-1 (hRFRP-1) and rat RFRP-1 rapidly and reversibly decreased shortening and relaxation in isolated mammalian cardiac myocytes in a dose dependent manner. The mammalian FaRP, 26RFa, structurally related to RFRP-1 by only an RFamide did not influence myocyte contractile function. The protein kinase C (PKC) inhibitor bisindolylmaleimide-1 blocked hRFRP-1 activity. Pretreatment with pertussis toxin (PTX) did not diminish hRFRP-1 influence on contractile function. In addition, intravenous injection of hRFRP-1 in mice decreased heart rate, stroke volume, ejection fraction, and cardiac output. Collectively these findings are consistent with the conclusion RFRP-1 is an endogenous signaling molecule that activates PKC and acts through a PTX-insensitive pathway to modulate cardiac contractile function. Taken together these negative chronotropic, inotropic, and lusitropic effects of hRFRP-1 are significant; they suggest direct acute cellular and organ-level responses in mammalian heart. This is the first known study to identify a mammalian FaRP with cardio-depressant effects, opening a new area of research on peptidergic modulation of contractile performance. The high degree of RFRP structure conservation from amphibians to mammals, and similarity to invertebrate cardioinhibitory peptides suggests RFRP-1 is involved in important physiological functions. Elucidation of mechanisms involved in hRFRP-1 synthesis, release, and signaling may aid the development of strategies to prevent or attenuate cardiac dysfunction.

The first nonsulfated sulfakinin activity reported suggests nsDSK acts in gut biology

Invertebrate sulfakinins are structurally and functionally homologous to vertebrate cholecystokinin (CCK) and gastrin. To date, sulfakinins are reported to require a sulfated tyrosine for activity; sulfated and nonsulfated CCK and gastrin are active. This is the first nonsulfated sulfakinin activity reported. Nonsulfated Drosophila melanogaster sulfakinins or drosulfakinins (nsDSK I; PheAspAspTyrGlyHisMetArgPheNH2) and (nsDSK II; GlyGlyAspAspGlnPheAspAspTyrGlyHisMetArgPheNH2) decreased the frequency of contractions of adult D. melanogaster foregut (crop) in vivo. The EC50's for nsDSK I and nsDSK II were approximately 2 x 10(-9)M and approximately 3 x 10(-8)M, respectively. Nonsulfated DSK peptides also decreased the frequency of larval anterior midgut contractions. Sulfated DSK peptides decreased both adult and larval gut contractions. Whether sulfation is required for sulfakinin activity may depend on where the peptide is applied, what tissue is analyzed, or what preparation is used. D. melanogaster contains two sulfakinin receptors, DSK-R1 and DSK-R2; vertebrates contain two CCK receptors, CCK-1 and CCK-2. A sulfated DSK I analog, [Leu7] sDSK I, binds to expressed DSK-R1; the corresponding nonsulfated analog does not bind to DSK-R1. No DSK-R2 binding data are reported. Sulfated and nonsulfated CCK peptides preferentially bind to CCK-1 or CCK-2, respectively. Sulfated and nonsulfated sulfakinins may bind to DSK-R1 or DSK-R2, respectively. Sulfakinin activities, spatial and temporal distribution, and homology to CCK and gastrin suggest sulfated and nonsulfated DSK peptides act in diverse roles in the neural and gastrointestinal systems including gut emptying and satiety.

A single amino acid substitution in the envelope protein of chimeric yellow fever-dengue 1 vaccine virus reduces neurovirulence for suckling mice and viremia/viscerotropism for monkeys

A chimeric yellow fever-dengue 1 (ChimeriVax-DEN1) virus was produced by the transfection of Vero cells with chimeric in vitro RNA transcripts. The cell culture supernatant was subjected to plaque purification for the identification of a vaccine candidate without mutations. Of 10 plaque-purified clones, 1 containing no mutation (clone J) was selected for production of the vaccine virus. During subsequent cell culture passaging of this clone for vaccine production, a single amino acid substitution (K to R) occurred in the envelope (E) protein at residue 204 (E204) (F. Guirakhoo, K. Pugachev, Z. Zhang, G. Myers, I. Levenbook, K. Draper, J. Lang, S. Ocran, F. Mitchell, M. Parsons, N. Brown, S. Brandler, C. Fournier, B. Barrere, F. Rizvi, A. Travassos, R. Nichols, D. Trent, and T. Monath, J. Virol. 78:4761-4775, 2004). The same mutation was observed in another clone (clone E). This mutation attenuated the virus in 4-day-old suckling mice inoculated by the intracerebral (i.c.) route and led to reduced viremia in monkeys inoculated by the subcutaneous or i.c. route. The histopathology scores of lesions in the brain tissue of monkeys inoculated with either the E204K or E204R virus were reduced compared to those for monkeys inoculated with the reference virus, a commercial yellow fever 17D vaccine (YF-VAX). Both viruses grew to significantly lower titers than YF-VAX in HepG2, a human hepatoma cell line. After intrathoracic inoculation into mosquitoes, both viruses grew to a similar level as YF-VAX, which was significantly lower than that of their wild-type DEN1 parent virus. A comparison of the E-protein structures of nonmutant and mutant viruses suggested the appearance of new intramolecular bonds between residues 204R, 261H, and 257E in the mutant virus. These changes may be responsible for virus attenuation through a change in the pH threshold for virus envelope fusion with the host cell membrane.

Safety and efficacy of chimeric yellow Fever-dengue virus tetravalent vaccine formulations in nonhuman primates

To construct chimeric YF/DEN viruses (ChimeriVax-DEN), the premembrane (prM) and envelope (E) genes of yellow fever (YF) 17D virus were replaced with those of each wild-type (WT) dengue (DEN) virus representing serotypes 1 to 4. ChimeriVax-DEN1-4 vaccine viruses were prepared by electroporation of Vero cells with RNA transcripts prepared from viral cDNA (F. Guirakhoo, J. Arroyo, K. V. Pugachev, C. Miller, Z.-X. Zhang, R. Weltzin, K. Georgakopoulos, J. Catalan, S. Ocran, K. Soike, M. Ratteree, and T. P. Monath, J. Virol. 75:7290-7304, 2001; F. Guirakhoo, K. Pugachev, J. Arroyo, C. Miller, Z.-X. Zhang, R. Weltzin, K. Georgakopoulos, J. Catalan, S. Ocran, K. Draper, and T. P. Monath, Virology 298:146-159, 2002). Progeny viruses were subjected to three rounds of plaque purifications to produce the Pre-Master Seed viruses at passage 7 (P7). Three further passages were carried out using U.S. current Good Manufacturing Practices (cGMP) to produce the Vaccine Lot (P10) viruses. Preclinical studies demonstrated that the vaccine candidates are replication competent and genetically stable and do not become more neurovirulent upon 20 passages in Vero cells. The safety of a tetravalent vaccine was determined and compared to that of YF-VAX in a formal monkey neurovirulence test. Brain lesions produced by the tetravalent ChimeriVax-DEN vaccine were significantly less severe than those observed with YF-VAX. The immunogenicity and protective efficacy of four different tetravalent formulations were evaluated in cynomolgus monkeys following a single-dose subcutaneous vaccination followed by a virulent virus challenge 6 months later. All monkeys developed low levels of viremia postimmunization, and all the monkeys that had received equal concentrations of either a high-dose (5,5,5,5) or a low-dose (3,3,3,3) formulation seroconverted against all four DEN virus serotypes. Twenty-two (92%) of 24 monkeys were protected as determined by lack of viremia post-challenge. This report is the first to demonstrate the safety of a recombinant DEN virus tetravalent vaccine in a formal neurovirulence test, as well as its protective efficacy in a monkey challenge model.

Safety and efficacy of low dose Escherichia coli enterotoxin adjuvant for urease based oral immunisation against Helicobacter pylori in healthy volunteers

BACKGROUND AND AIMS

Escherichia coli heat labile enterotoxin (LT) at doses of 5 micro g or 10 micro g has adjuvant activity for oral immunisation in humans infected with Helicobacter pylori, but causes severe diarrhoea. This study was undertaken to establish a safe and effective dose of LT, to confirm the safety of recombinant urease, and to compare the immunogenicity of orally compared with enterically delivered urease.

METHODS

42 healthy adults without present or past H pylori infection were randomised to receive 60 mg recombinant H pylori urease in soluble or in encapsulated form, given with doses of LT ranging from 0 micro g to 2.5 micro g. Four oral doses were administered at day 1, 8, 29, and 57. Specific IgG, IgA, and antibody secreting cells were measured as well as total alpha4beta7 integrin positive lymphocyte responses.

RESULTS

Enterically delivered urease was well tolerated and no serious adverse events occurred. Mild diarrhoea (one to four loose stools) occurred after the first immunisation in 50% (6 of 12) of the volunteers exposed to 2.5 micro g LT (p=0.06; paired t test, compared with baseline) but not in volunteers exposed to lower LT doses. Immune responses occurred in five (p=0.048; Fisher's exact test), one, two, and one of six subjects exposed to 2.5 micro g, 0.5 micro g, 0.1 micro g, and no LT, respectively. Significant CD4(+), CD69(+), and CD45RO(hi) responses occurred over time among alpha4beta7(hi) lymphocytes in volunteers receiving 2.5 micro g LT. Enterically delivered urease induced higher lymphocyte responses than soluble urease.

CONCLUSIONS

The safety of H pylori urease is confirmed. Oral LT may conserve its adjuvant activity at low doses with minimal side effects.

Drosophila melanogaster myotropins have unique functions and signaling pathways

Drosophila melanogaster TDVDHVFLRFamide (DMS), SDNFMRFamide, and pEVRFRQCYFNPISCF (FLT) represent three structurally distinct peptide families. Each peptide decreases heart rate albeit with different magnitudes and time-dependent responses. DMS and FLT are expressed in the crop and decrease crop motility; however, SDNFMRFamide expression and effect on the crop has not been reported. These data suggest the peptides have different physiological roles. The peptides have non-overlapping expression patterns in neural tissue, which suggests different mechanisms regulate their synthesis and release. The structures, expression patterns, and activities of the myotropins suggest they have important but different roles in biology and different signaling pathways.

A putative tachykinin receptor in the cockroach brain: molecular cloning and analysis of expression by means of antisera to portions of the receptor protein

Tachykinins constitute a neuropeptide family that mediate their actions via a subfamily of structurally related G-protein-coupled receptors. Two receptors, Drosophila neurokinin receptor (NKD) and Drosophila tachykinin receptor (DTKR), with sequence similarities to mammalian tachykinin receptors have previously been cloned in Drosophila. In this study we have isolated a cockroach (Leucophaea maderae) cDNA clone by screening a brain cDNA library with a degenerate oligonucleotide probe based on a conserved sequence within the seventh transmembrane region of the Drosophila tachykinin receptors. This clone, Leucophaea tachykinin receptor (LTKR), encodes a portion of a putative receptor which could be aligned with the C-terminal half of members of the tachykinin receptor subfamily. In the fifth, sixth and seventh transmembrane regions the deduced amino acid sequence of LTKR exhibits 79% sequence identity to the DTKR receptor and 54% to that of NKD. This suggests that LTKR is orthologous to the DTKR receptor. To study the distribution of the predicted LTKR protein by immunocytochemistry, antisera were raised against synthetic peptides corresponding to a region of the third intracellular loop of LTKR. In the cockroach brain immunoreactive neuronal processes were seen in several synaptic neuropils of the protocerebrum and tritocerebrum as well as in the frontal ganglion. Some immunoreactive neuronal cell bodies were detected in the protocerebrum. Double labeling immunocytochemistry revealed that there is a substantial superposition between distribution of LTKR and processes containing tachykinin-related peptide (TRP). Some brain areas, however, only display TRP immunoreactive processes and no LTKR, suggesting the presence of at least one more TRP receptor type.

Serum total thyroxine, total triiodothyronine, free thyroxine, and thyrotropin concentrations in dogs with nonthyroidal disease

OBJECTIVE

To determine whether nonthyroidal disease of various causes and severity is associated with abnormalities in baseline serum concentrations of total thyroxine (T4), triiodothyronine (T3), free T4, or thyrotropin (thyroid-stimulating hormone [TSH]) in dogs believed to be euthyroid.

DESIGN

Case-control study.

ANIMALS

223 dogs with confirmed nonthyroidal diseases and presumptive normal thyroid function, and 150 clinically normal dogs.

PROCEDURE

Serum total T4, total T3, free T4, and TSH concentrations were measured in dogs with confirmed nonthyroidal disease. Reference ranges for hormone concentrations were established on the basis of results from 150 clinically normal dogs.

RESULTS

In dogs with nonthyroidal disease, median serum concentrations of total T4, total T3, and free T4 were significantly lower than those in clinically normal dogs. Median serum TSH concentration in sick dogs was significantly greater than that of clinically normal dogs. When stratified by severity of disease (ie, mild, moderate, and severe), dogs with severe disease had low serum concentrations of total T4, total T3, or free T4 more commonly than did dogs with mild disease. In contrast, serum TSH concentrations were more likely to remain within the reference range regardless of severity of disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that serum total T4, free T4, and total T3 concentrations may be low (ie, in the hypothyroid range) in dogs with moderate to severe nonthyroidal disease. Serum TSH concentrations are more likely to remain within the reference range in sick dogs.

Polyuria and polydipsia. Diagnostic approach and problems associated with patient evaluation

Primary disorders of water balance (central diabetes insipidus [DI], nephrogenic DI, and psychogenic polydipsia) should always be considered in the differential diagnosis of polyuria and polydipsia. In general, animals with these disorders have only one laboratory abnormality: a low urine specific gravity. In most instances, the more common causes of polyuria and polydipsia (e.g., hyperadrenocorticism, chronic renal failure, pyelonephritis, pyometra) have specific and obvious abnormalities associated with the complete blood cell count, the serum chemistry profile, and urinalysis. In some cases, however, a low urine specific gravity may be the only abnormality associated with these more common findings. The workup for polyuria and polydipsia can be tedious, time-consuming, expensive, confusing, and not without significant patient morbidity, especially in those cases with normal or near-normal blood work. This article focuses on the diagnostic approach and problems associated with diagnostic testing in patients with disorders of water balance.

Gene trees and species trees are not the same

The relationship between species is usually represented as a bifurcating tree with the branching points representing speciation events. The ancestry of genes taken from these species can also be represented as a tree, with the branching points representing ancestral genes. The time back to the branching points, and even the branching order, can be different between the two trees. This possibility is widely recognized, but the discrepancies are often thought to be small. A different picture is emerging from new empirical evidence, particularly that based on multiple loci or on surveys with a wide geographical scope. The discrepancies must be taken into account when estimating the timing of speciation events, especially the more recent branches. On the positive side, the different timings at different loci provide information about the ancestral populations.

Undergraduate students' understanding of division of fractions

This exploratory study was designed to assess undergraduate students' understanding of division of fractions. A paper and pencil instrument was administered as a pre- and posttest to 59 undergraduate students who major in elementary education. Analysis by independent t test of written responses provided by students on the pre- and posttests showed lack of understanding, even postinstruction.

Measurement of serum concentrations of free thyroxine, total thyroxine, and total triiodothyronine in cats with hyperthyroidism and cats with nonthyroidal disease

OBJECTIVE

To determine the usefulness of measuring serum free thyroxine (T4) concentration as a diagnostic test for hyperthyroidism in cats, and to determine the influence of nonthyroidal disease on free T4 concentration in cats without hyperthyroidism.

DESIGN

Prospective case series.

ANIMALS

917 cats with untreated hyperthyroidism, 221 cats with nonthyroidal disease, and 172 clinically normal cats.

PROCEDURE

Serum free T4, total T4, and total triiodothyronine (T3) concentrations were measured in cats with untreated hyperthyroidism and cats with nonthyroidal disease. Serum total T4 and T3 concentrations were determined by use of radioimmunoassay, and free T4 concentration was measured by use of direct equilibrium dialysis. Reference ranges for hormone concentrations were established on the basis of results from the 172 clinically normal cats.

RESULTS

Sensitivity of serum free T4 concentration as a diagnostic test for hyperthyroidism was significantly higher than the test sensitivity of either total T4 or T3 concentration. Of the 221 cats with nonthyroidal disease, 14 had a high free T4 concentration (ie, false-positive result). Therefore, calculated specificity of measuring serum free T4 concentration as a diagnostic test for hyperthyroidism was significantly lower than test specificity of measuring either the total T4 or T3 concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that determination of free T4 concentration is useful in the diagnosis of hyperthyroidism, especially in cats in which hyperthyroidism is suspected but total T4 and T3 concentrations are within reference ranges. However, because some cats with nonthyroidal disease have high serum free T4 concentrations, hyperthyroidism should not be diagnosed solely on the finding of high free T4 concentration.

Safety and immunogenicity of increasing doses of a Clostridium difficile toxoid vaccine administered to healthy adults

Clostridium difficile is a major cause of nosocomial diarrhea in industrialized countries. Although most illnesses respond to available therapy, infection can increase morbidity, prolong hospitalization, and produce life-threatening colitis. Vaccines are being explored as an alternative means for protecting high-risk individuals. We assessed the safety, immunogenicity, and dose response of a parenteral vaccine containing C. difficile toxoids A and B. Thirty healthy adults were assigned to receive four spaced inoculations on days 1, 8, 30, and 60 with one of three doses of vaccine (6.25, 25, or 100 microg). At each dose level, subjects were randomized, in a double-blind fashion, to receive either the soluble toxoids (n = 5) or toxoids adsorbed to alum (n = 5). Subjects were monitored for clinical and immunologic responses to vaccination. Vaccination was generally well tolerated, with occasional, usually mild, systemic reactions (abdominal pain, arthralgia, and diarrhea). The most common local reaction, mild arm pain, was reported by all recipients of the toxoid-alum formulation. Nearly all subjects (> or = 90%) developed vigorous serum antibody responses to both toxins, as measured by immunoglobulin G (IgG) enzyme-linked immunosorbent assay and neutralization of cytotoxicity, whereas fecal IgA increases occurred in approximately 50%. Statistically significant effects of dose and formulation on immunogenicity were not seen, although antibody levels tended to be higher with the alum-adjuvanted formulations and with increasing doses of soluble toxoid. Serum antibody responses among the toxoid-alum group appeared to plateau at 25 microg. We concluded that the C. difficile toxoid vaccine is safe and immunogenic in healthy volunteers. Further development as a prophylactic vaccine or for producing C. difficile hyperimmune globulin is justified.

DPKQDFMRFamide expression is similar in two distantly related Drosophila species

Drosophila melanogaster DPKQDFMRFamide was isolated and its expression reported. Distribution of DPKQDFMRFamide immunoreactivity is now described in Drosophila virilis. DPKQDFMRFamide antibody stained a cell in the subesophageal ganglion in embryo. DPKQDFMRFamide antibody stained cells in the superior protocerebrum, subesophageal ganglion, thoracic ganglia, and an abdominal ganglion in larva, pupa, and adult. DPKQDFMRFamide antibody stained an additional pair of cells in the optic lobe and a cell in the lateral protocerebrum in adult. Structure identity and similar distribution of DPKQDFMRFamide in D. virilis and D. melanogaster, two distantly related Drosophila species, suggests an important and conserved activity for the peptide.

Dietary patterns among a national random sample of British adults

STUDY OBJECTIVES

To identify groups within the UK male and female population who report similar patterns of diet.

DESIGN

National representative dietary survey, using seven day weighed dietary records, of men and women aged 16-64 years living in private households in Great Britain in 1986-7. Cluster analysis was used to aggregate participants into diet groups.

SETTING

Great Britain.

PARTICIPANTS

1087 men and 1110 women.

RESULTS

93% of men and 86% of women fell into one of four distinct diet groups. Among men the most prevalent diet group was "beer and convenience food" (34% of the male population); second was "traditional British diet" (18%); third was "healthier but sweet diet" (17.5%) and fourth was "healthier diet " (17%). Among women, the most prevalent diet group was " traditional British diet" (32%); second, was "healthy cosmopolitan diet" (25%); third was a "convenience food diet" (21%); and fourth was "healthier but sweet diet" (15%). There were important differences in nutrient profile, sociodemographic and behavioural characteristics between diet groups.

CONCLUSIONS

Cluster analysis identified four diet groups among men and four among women, which differed not only in terms of reported dietary intakes, but also with respect to nutrient, social and behavioural profiles. The groups identified could provide a useful basis for development, monitoring and targeting of public health nutrition policy in the UK.

Innervation of dromyosuppressin (DMS) immunoreactive processes and effect of DMS and benzethonium chloride on the Phormia regina (Meigen) crop

Antibody to the dipteran myosuppressin peptide, dromyosuppressin, TDVDHVFLRFamide, stained cells and fibers in the brain, optic lobes, subesophageal ganglion, and thoracico-abdominal ganglion of the blow fly, Phormia regina (Meigen). Dromyosuppressin-like immunoreactive fibers were detected in the cardiac recurrent nerve, hypocerebral ganglion/corpora cardiaca complex, crop duct, and crop. In order to explore the mechanisms involved in regulating crop movement, we established an in vitro bioassay. The basal rate of crop movement was 50.8 +/- 1.5 contractions per minute. Application of 1 microl of saline to the crop did not significantly affect the rate of movement compared to the basal rate (46.1 +/- 1.1 contractions per minute, P < 0.05). Application of 1 microl 10(-6) M dromyosuppressin or 1 microl 10(-3) M benzethonium chloride to the crop slowed the rate to 2.2 +/- 0.2 and 6.1 +/- 0.7 contractions per minute, respectively. Although other data have previously been interpreted to suggest that dipteran crop contractions do not include a neural component, the neuropeptide dromyosuppressin affected P. regina crop motility. Innervation of the crop and crop duct by dromyosuppressin immunoreactive processes that originated in the central nervous system and the effect of dromyosuppressin on crop muscle contractions suggest that dromyosuppressin is released locally to modulate crop contractions and that crop motility is under neural regulation. Myosuppressins isolated from numerous insects have a high degree of structure identity and reduce spontaneous muscle contractions of the hindgut, oviduct, and heart. Benzethonium chloride, previously identified as a myosuppressin agonist on the cockroach hindgut and locust oviduct, mimicked the effect of dromyosuppressin on the crop. This suggests that structural requirements for myosuppressin receptor binding in the cockroach hindgut, locust oviduct, and fruit fly crop are similar.