Contrasting patterns of selection on the size and coloration of a female plumage ornament in common yellowthroats.

Females often possess ornaments that appear smaller and duller than homologous traits in males. These ornaments may arise as nonfunctional by-products of sexual selection in males and cause negative viability or fecundity selection in females in proportion to the cost of their production and maintenance. Alternatively, female ornaments may function as signals of quality that are maintained by sexual or social selection. In a 4-year study of 83 female common yellowthroats (Geothlypis trichas) and their 222 young, we found strong viability and fecundity selection on the yellow bib, a carotenoid-based plumage ornament that is a target of sexual selection in males. Females with larger bibs were older, larger and more fecund than females with smaller bibs. However, bib size positively covaried with bib total brightness and carotenoid chroma, aspects of bib coloration that were under negative viability and fecundity selection. Females with more colourful bibs laid fewer eggs in their first clutch, were more likely to suffer total brood loss due to predation and were less likely to return to the study area. Selection against bib coloration limits the value of bib size as a quality indicator in females and may constrain the elaboration of bib attributes in males.

Spatial distribution of nests constrains the strength of sexual selection in a warbler.

In socially monogamous species, extra-pair paternity may increase the strength of intersexual selection by allowing males with preferred phenotypes to monopolize matings. Several studies have found relationships between male signals and extra-pair mating, but many others fail to explain variation in extra-pair mating success. A greater appreciation for the role that ecological contingencies play in structuring behavioural processes may help to reconcile contradictory results. We studied extra-pair mating in a spatial context in the common yellowthroat (Geothlypis trichas), a territorial wood warbler. Over the course of 6 years, we observed 158 breeding attempts by 99 males, resulting in a total of 369 nests and 520 sampled nestlings. The spatial distribution of territories varied greatly, with males having between 0 and 10 close neighbours and between three and 39 neighbouring nestlings close enough to represent extra-pair siring opportunities. Both within-pair and extra-pair reproductive success increased with breeding density, but the opportunity for sexual selection and strength of selection varied with density. Total variance in reproductive success was highest at low density and was mostly explained by variation in within-pair success. In contrast, at high density, both within-pair and extra-pair successes contributed substantially to variance in reproductive success. The relationships between plumage and extra-pair mating also varied by density; plumage was under strong sexual selection via extra-pair mating success at high density, but no selection was detected at low density. Thus, ecological factors that structure social interactions can drive patterns of sexual selection by facilitating or constraining the expression of mating preferences.

Evaluation of the TREX1 gene in a large multi-ancestral lupus cohort.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disorder with a complex pathogenesis in which genetic, hormonal and environmental factors have a role. Rare mutations in the TREX1 gene, the major mammalian 3'-5' exonuclease, have been reported in sporadic SLE cases. Some of these mutations have also been identified in a rare pediatric neurological condition featuring an inflammatory encephalopathy known as Aicardi-Goutières syndrome (AGS). We sought to investigate the frequency of these mutations in a large multi-ancestral cohort of SLE cases and controls. A total of 40 single-nucleotide polymorphisms (SNPs), including both common and rare variants, across the TREX1 gene, were evaluated in ∼8370 patients with SLE and ∼7490 control subjects. Stringent quality control procedures were applied, and principal components and admixture proportions were calculated to identify outliers for removal from analysis. Population-based case-control association analyses were performed. P-values, false-discovery rate q values, and odds ratios (OR) with 95% confidence intervals (CI) were calculated. The estimated frequency of TREX1 mutations in our lupus cohort was 0.5%. Five heterozygous mutations were detected at the Y305C polymorphism in European lupus cases but none were observed in European controls. Five African cases incurred heterozygous mutations at the E266G polymorphism and, again, none were observed in the African controls. A rare homozygous R114H mutation was identified in one Asian SLE patient, whereas all genotypes at this mutation in previous reports for SLE were heterozygous. Analysis of common TREX1 SNPs (minor allele frequency (MAF)>10%) revealed a relatively common risk haplotype in European SLE patients with neurological manifestations, especially seizures, with a frequency of 58% in lupus cases compared with 45% in normal controls (P=0.0008, OR=1.73, 95% CI=1.25-2.39). Finally, the presence or absence of specific autoantibodies in certain populations produced significant genetic associations. For example, a strong association with anti-nRNP was observed in the European cohort at a coding synonymous variant rs56203834 (P=2.99E-13, OR=5.2, 95% CI=3.18-8.56). Our data confirm and expand previous reports and provide additional support for the involvement of TREX1 in lupus pathogenesis.

Impact of age and sex on mycobacterial immunity in an area of high tuberculosis incidence.

SETTING: The extent of immune reactivity measured by the tuberculin skin test (TST) and interferon-gamma (IFN-gamma) T-cell assays is usually not analysed. OBJECTIVE: To determine the impact of age and sex on assay positivity and on the extent of reactivity of both TST and T-cell assays in young persons in an area of South Africa with high TB transmission. RESULTS: Age had a strong impact on assay positivity for all seven immune phenotypes tested (P < 0.0007). Among positive responders, the extent of purified protein derivative (PPD) triggered IFN-gamma release (P < 0.003) was sensitive to age. ESAT-6 triggered IFN-gamma release (day 7, P = 0.03) and the frequency of PPD-specific IFN-gamma(+)CD4(+) (P = 0.03) and IFN-gamma(+)CD8(+) cells (P = 0.04) were weakly dependent on age. By contrast, the extent of TST induration was insensitive to age (P > 0.05), and sex had no significant impact on any phenotype measured (P > 0.05). The high proportion of positive responders in the 1-10 year age-group observed with long-term whole blood assays, but not with 3-day assays and TST, suggests that long-term whole blood assays may be confounded by bacille Calmette-Guérin vaccination in this age group. CONCLUSION: There is a significant impact of age, but not sex, on different assays of immune reactivity in this high TB transmission setting.

CaMKIIT287 and T305 regulate history-dependent increases in alpha agonist-induced vascular tone.

CaMKII is a calcium and calmodulin-activated kinase that has been shown to regulate learning and memory in the brain, and contractility in blood vessels. Following Ca activation, CaMKII autophosphorylates, gaining a calcium-independent autonomous activity that reflects a molecular memory of having previously come into contact with calcium. The present study addresses whether the molecular memory properties of CaMKII are involved in the modulation of sustained vascular tone. We demonstrate a history-dependence of alpha agonist-induced vascular tone and show that CaMKII activation in vascular cells is also history dependent. Autophosphorylation of Thr287, which is classically associated with autonomous activity, does not persist during tone maintenance after transient increases in intracellular calcium levels. However, we have found that another site, Thr305, known from in vitro studies to be inhibitory, is regulated by alpha agonists in that the inhibitory action is removed, thus leading to a delayed reactivation of CaMKII as measured by Thr287 phosphorylation. By the use of a small molecule CaMKII inhibitor (KN93) as well as a decoy peptide (autoinhibitory peptide; AIP) we show a cause and effect relationship between CaMKII reactivation and sustained vascular tone maintenance. Thus, it appears that a complex interplay between the regulation of Thr305 and Thr287 provides a novel mechanism by which a history-dependence is developed and contributes to a new facet of molecular memory for CaMKII of relevance to vascular tone maintenance.

Reduced in vitro functional activity of human NRAMP1 (SLC11A1) allele that predisposes to increased risk of pediatric tuberculosis disease.

Polymorphic variants within the human natural resistance-associated macrophage protein-1 (NRAMP1, also known as SLC11A1) gene have been shown to impact on susceptibility to tuberculosis in different human populations. In the mouse, Nramp1 is expressed at the macrophage phagosomal membrane and its activity can be assayed by the relative acquisition of mannose 6-phosphate receptor (M6PR) in Salmonella-containing vacuoles. Based on this M6PR recruitment assay, we have now developed an assay in primary human macrophages to test the function of human NRAMP1 gene variants. First, we established that M6PR acquisition was significantly higher (P = 0.002) in human U-937 monocytic cell lines transfected with NRAMP1 as compared to untransfected U-937 cells. Second, the M6PR assay was shown to be highly reproducible for NRAMP1 activity in monocyte-derived macrophages (MDM) from healthy volunteers. Finally, the assay was investigated in MDM from pediatric tuberculosis patients and significantly lower NRAMP1 activity was detected in MDM from individuals homozygous for the NRAMP1-274 high-risk allele (CC genotype) in comparison to heterozygous individuals (CT genotype; P=0.013). The present study describes both an assay for human NRAMP1 functional activity and concomitant evidence for reduced NRAMP1 function in the common genetic variant shown to be associated with tuberculosis susceptibility in pediatric patients.

H-NS represses Salmonella enterica serovar Typhimurium dsbA expression during exponential growth.

Disulfide bond formation catalyzed by disulfide oxidoreductases occurs in the periplasm and plays a major role in the proper folding and integrity of many proteins. In this study, we were interested in elucidating factors that influence the regulation of dsbA, a gene coding for the primary disulfide oxidoreductase found in Salmonella enterica serovar Typhimurium. Strains with mutations created by transposon mutagenesis were screened for strains with altered expression of dsbA. A mutant (NLM2173) was found where maximal expression of a dsbA::lacZ transcriptional fusion occurred in the exponential growth phase in contrast to that observed in the wild type where maximal expression occurs in stationary phase. Sequence analysis of NLM2173 demonstrated that the transposon had inserted upstream of the gene encoding H-NS. Western immunoblot analysis using H-NS and StpA antibodies showed decreased amounts of H-NS protein in NLM2173, and this reduction in H-NS correlated with an increase of StpA protein. Northern blot analysis with a dsbA-specific probe showed an increase in dsbA transcript during exponential phase of growth. Direct binding of H-NS to the dsbA promoter region was verified using purified H-NS in electrophoretic mobility shift assays. Thus, a reduction in H-NS protein is correlated with a derepression of dsbA in NLM2173, suggesting that H-NS normally plays a role in suppressing the expression of dsbA during exponential phase growth.

Salmonella enterica serovar typhimurium rdoA is growth phase regulated and involved in relaying Cpx-induced signals.

The disulfide oxidoreductase, DsbA, mediates disulfide bond formation in proteins as they enter or pass through the periplasm of gram-negative bacteria. Although DsbA function has been well characterized, less is known about the factors that control its expression. Previous studies with Escherichia coli demonstrated that dsbA is part of a two-gene operon that includes an uncharacterized, upstream gene, yihE, that is positively regulated via the Cpx stress response pathway. To clarify the role of the yihE homologue on dsbA expression in Salmonella enterica serovar Typhimurium, the effect of this gene (termed rdoA) on the regulation of dsbA expression was investigated. Transcriptional assays assessing rdoA promoter activity showed growth phase-dependent expression with maximal activity in stationary phase. Significant quantities of rdoA and dsbA transcripts exist in serovar Typhimurium, but only extremely low levels of rdoA-dsbA cotranscript were detected. Activation of the Cpx system in serovar Typhimurium increased synthesis of both rdoA- and dsbA-specific transcripts but did not significantly alter the levels of detectable cotranscript. These results indicate that Cpx-mediated induction of dsbA transcription in serovar Typhimurium does not occur through an rdoA-dsbA cotranscript. A deletion of the rdoA coding region was constructed to definitively test the relevance of the rdoA-dsbA cotranscript to dsbA expression. The absence of RdoA affects DsbA expression levels when the Cpx system is activated, and providing rdoA in trans complements this phenotype, supporting the hypothesis that a bicistronic mechanism is not involved in serovar Typhimurium dsbA regulation. The rdoA null strain was also shown to be altered in flagellar phase variation. First it was found that induction of the Cpx stress response pathway switched flagellar synthesis to primarily phase 2 flagellin, and this effect was then found to be abrogated in the rdoA null strain, suggesting the involvement of RdoA in mediating Cpx-related signaling.

Effect of compost and manure soil amendments on nematodes and on yields of potato and barley: a 7-year study.

A 7-year study located in Prince Edward Island, Canada, examined the influence of compost and manure on crop yield and nematode populations. The compost used in this study consisted of cull waste potatoes, sawdust, and beef manure in a 3:3:1 ratio, respectively. No plant-parasitic nematodes were detected in samples collected from windrow compost piles at 5- and 30-cm depths prior to application on field plots. Low population densities of bacterial-feeding nematodes were recovered from compost windrows at the 5-cm depth. Field plots of potato (Solanum tuberosum cv. Kennebec) received compost applied at 16 metric tonnes per hectare, or beef manure applied at 12 metric tonnes per hectare. An adjacent trial with barley (Hordeum vulgare cv. Mic Mac) received only the compost treatment. In both trials the experimental design was a complete randomized block with four replicates. Data averaged over seven growing seasons indicated that population levels of root-lesion nematodes (primarily Pratylenchus penetrans) were higher in root-zone soil in potato plots treated with either compost or manure compared to the untreated control plots. The soil amendments did not affect root-knot nematode (Meloidogyne hapla) population densities in the potato plots, but clover-cyst nematodes (Heterodera trifolii) were more numerous in the root-zone soils of barley treated with compost compared to the untreated plots. Numbers of bacterial-feeding nematodes (primarily Diplogaster lheritieri) were greater in soil in potato plots treated with manure and in soil around barley roots than in untreated plots. Total yields of potato tubers averaged over seven growing seasons increased by 27% in the plots treated with either compost or manure. Grain yields of barley also were increased by 12% when compost was applied. These results indicated that organic amendments increased crop yields, but the impacts on different nematode species varied and usually increased soil population levels.

Salmonella typhimurium DsbA is growth-phase regulated.

Northern blot analyses, transcription assays using a dsbA::lacZ transcriptional fusion, and primer extension mapping were used to characterize the promoter region of dsbA from Salmonella typhimurium. Transcription assays measuring promoter activity of a 258-bp segment of DNA immediately upstream of the dsbA translational start site showed strong growth-phase dependence, with maximal expression in stationary phase and high levels of expression maintained for at least 72 h. This expression was not RpoS-dependent. Two transcripts initiating in the dsbA promoter region were mapped by primer extension analysis and their levels were monitored by Northern blot analysis. Growth conditions such as pH and O(2) levels affected dsbA transcription independently of growth phase. The data suggests that the promoter region of S. typhimurium is not constitutively activated. Its regulation may reflect a requirement for DsbA during conditions resulting in stationary-phase-like growth in the environment.

Calmodulin levels are dynamically regulated in living vascular smooth muscle cells.

The total unbound calmodulin (i.e., not bound to target proteins) level in living smooth muscle cells from the ferret portal vein was monitored with a low-affinity, calmodulin-binding peptide tagged with an environmentally sensitive fluorophore. GS17C, a previously characterized peptide, from the calmodulin-binding domain of caldesmon was tagged with iodoacetyl nitrobenz-2-oxa-1,3-diazole (NBD) or, as a negative control, with iodoacetylfluorescein isothiocyanate. Increases in NBD-GS17C fluorescence were detected by using confocal microscopy when chemically loaded cells were stimulated with solutions of elevated [K(+)] or the calcium ionophore 4-bromoA-23187 to elicit increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) quantified by fura 2. Increases in peptide fluorescence were detected in response to a phorbol ester in the absence of changes in [Ca(2+)](i). These changes were blocked by the addition of the calmodulin antagonist calmidazolium. These results suggest that the total unbound intracellular calmodulin levels may be sufficient to regulate the activity of caldesmon and, furthermore, that phosphorylation of protein kinase C substrates may increase the level of available calmodulin in living smooth muscle cells.

Regulation of protein kinase C by the cytoskeletal protein calponin.

Previous studies from this laboratory have shown that, upon agonist activation, calponin co-immunoprecipitates and co-localizes with protein kinase Cepsilon (PKCepsilon) in vascular smooth muscle cells. In the present study we demonstrate that calponin binds directly to the regulatory domain of PKC both in overlay assays and, under native conditions, by sedimentation with lipid vesicles. Calponin was found to bind to the C2 region of both PKCepsilon and PKCalpha with possible involvement of C1B. The C2 region of PKCepsilon binds to the calponin repeats with a requirement for the region between amino acids 160 and 182. We have also found that calponin can directly activate PKC autophosphorylation. By using anti-phosphoantibodies to residue Ser-660 of PKCbetaII, we found that calponin, in a lipid-independent manner, increased auto-phosphorylation of PKCalpha, -epsilon, and -betaII severalfold compared with control conditions. Similarly, calponin was found to increase the amount of (32)P-labeled phosphate incorporated into PKC from [gamma-(32)P]ATP. We also observed that calponin addition strongly increased the incorporation of radiolabeled phosphate into an exogenous PKC peptide substrate, suggesting an activation of enzyme activity. Thus, these results raise the possibility that calponin may function in smooth muscle to regulate PKC activity by facilitating the phosphorylation of PKC.

Ca2+-calmodulin-dependent protein kinase II-dependent activation of contractility in ferret aorta.

1. The present study was undertaken to determine whether Ca2+-calmodulin-dependent protein kinase II (CaMKII) participates in the regulation of vascular smooth muscle contraction, and if so, to investigate the nature of the downstream effectors. 2. The contractility of isolated ferret aorta was measured while inhibiting CaMKII either with antisense oligodeoxynucleotides against CaMKII or with the CaMKII inhibitor KN93. 3. Treatment with antisense oligodeoxynucleotides against CaMKII resulted in, on average, a decrease in protein levels of CaMKII to 56 % of control levels and significantly decreased the magnitude of the contraction in response to 51 mM potassium physiological saline solution (KCl). Contraction in response to the phorbol ester DPBA was not significantly affected. 4. The CaMKII blocker KN93 also resulted in a significant decrease in the force induced by 51 mM KCl but caused no significant change in the contraction in response to DPBA or the alpha-adrenoceptor agonist phenylephrine. 5. During contraction with 51 mM KCl, both CaMKII and mitogen-activated protein kinase (MAPK) activity increased, as determined by phospho-specific antibodies. The MAPK phosphorylation level was inhibited by KN93, PD098059 (a MAPK kinase (MEK) inhibitor) and calcium depletion. 6. Myosin light chain (LC20) phosphorylation also increased during contraction with KCl and the increase was significantly blocked by PD098059 as well as by both KN93 and antisense oligodeoxynucleotides to CaMKII. 7. The data indicate that CaMKII plays a significant role in the regulation of smooth muscle contraction and suggest that CaMKII activates a pathway by which MAPK activation leads to phosphorylation of LC20 via activation of myosin light chain kinase.

Regulation of vascular smooth muscle tone by N-terminal region of caldesmon. Possible role of tethering actin to myosin.

To assess the functional significance of tethering actin to myosin by caldesmon in the regulation of smooth muscle contraction, we investigated the effects of synthetic peptides, containing the myosin-binding sequences in the N-terminal region of caldesmon, on force directly recorded from single permeabilized smooth muscle cells of ferret portal vein. Two peptides were used, IK29C and MY27C, containing residues from Ile(25) to Lys(53) and from Met(1) to Tyr(27) of the human and chicken caldesmon sequence, respectively, plus an added cysteine at the C terminus. In cells clamped at pCa 6. 7, both peptides increased basal tone. Pretreatment of cells at pCa 6.7 with IK29C or MY27C decreased the amplitude of subsequent phenylephrine-induced contractions but not microcystin-racemic mixture-induced contractions. In all cases the effects of the peptides were concentration-dependent, and IK29C was more potent than MY27C, in agreement with their relative affinity toward myosin. The peptides were ineffective after the phenylephrine contraction was established. MY27C did not further increase the magnitude of contraction caused by a maximally effective concentration of IK29C, consistent with the two peptides having the same mechanism of action. Neither polylysine nor two control peptides containing scrambled sequences of IK29C, which do not bind myosin, had any effect on basal or phenylephrine-induced force. Our results suggest that IK29C and MY27C induce contraction by competing with the myosin-binding domain of endogenous caldesmon. Digital imaging of fluoroisothiocyanate-tagged IK29C confirmed the association of the peptide with intracellular filamentous structures. The results are consistent with a model whereby tethering of actin to myosin by caldesmon may play a role in regulating vascular tone by positioning the C-terminal domain of caldesmon so that it is capable of blocking the actomyosin interaction.

The Effect of Marigolds (Tagetes spp.) and Other Cover Crops on Pratylenchus penetrans and on Following Potato Crops.

Root-lesion nematodes (primarily Pratylenchus penetrans) were monitored in two marigold cultivars (Tagetes tenuifolia cv. Nemakill and cv. Nemanon), annual ryegrass (Lolium multiflorum cv. Lemtal), red clover (Trifolium pratense cv. Florex), and soybean (Glycine max cv. Proteus), and in the following potato (Solanum tuberosum cv. Superior) crop during three growth sequences. Meadow fescue (Festuca elatior cv. Miner) and bee plant (Phacelia tanacetifolia cv. Gipha) were added to the trial in the second year. Black-eyed Susan (Rudbeckia hirta, unidentified cv.) and two additional marigold cultivars (T. patula ssp. nana, unidentified cv., and T. erecta cv. Crackerjack) were included in the final sequence. Population levels of root-lesion nematodes were consistently lower under marigolds compared to the other cover crops tested. Correspondingly, average potato tuber yields were significantly higher (8-14%) when potato followed marigolds. The highest levels of root-lesion nematodes occurred under red clover and soybean, and the average potato tuber yields were lowest following these crops.

Treatment of drug-induced agranulocytosis with haematopoietic growth factors: a review of the clinical experience.

Although drug-induced agranulocytosis is infrequent, it is of concern as the mortality rate ranges from 6 to 10%. Since the approval of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), these drugs have been increasingly used in the management of drug-induced agranulocytosis. Unfortunately, most of the data regarding the use of these agents in patients with drug-induced agranulocytosis comes from case reports. In light of the low incidence of drug-induced agranulocytosis, the large variety of offending drugs with potentially different toxic mechanisms and the wide range of neutropenia duration among patients with agranulocytosis, randomised, double-blind studies are unlikely to be performed. Case reports provide promising results with a shortening in the duration of agranulocytosis, a possible reduction in the duration of hospitalisation and the fatality rate in patients treated with haematopoietic growth factors (HGF) compared with historical controls. A therapeutic effect is also suggested by reports of reductions in the neutrophil count after HGF discontinuation following an initial increase. The results of recent case series are less positive, with only a moderate, but usually not significant, reduction in the duration of neutropenia in patients treated with HGF, as compared with those receiving routine care. A Japanese study indicated that G-CSF was effective in patients with mild-to-moderate antithyroid drug-induced neutropenia, whereas no clear benefit was apparent in those with severe neutropenia. Several factors, for example, early recognition and improved management of individual cases with better supportive care, have contributed to a decrease in the overall mortality of drug-induced agranulocytosis. HGF are expected to further reduce mortality. Guidelines for the use of HGF in patients with febrile neutropenia, as established by the American Society of Clinical Oncology, are probably valuable for the management of drug-induced agranulocytosis. In accordance with these recommendations, the use of HGF may be recommended in patients with severe neutropenia and/or poor prognostic factors. Whether the absence of myeloid precursors or presence of promyelocytes or myelocytes in bone marrow examination represents optimal conditions for HGF treatment is still unknown. Most authors agree that treatment should be administered early in the course of the disease. An interesting approach, in which treatment decisions are based on the granulocyte count 4 hours after a single dose of G-CSF in patients with anthithyroid drug-associated neutropenia should be more extensively evaluated.

The expression of functional postsynaptic alpha2-adrenoceptors in the corpus cavernosum smooth muscle.

1. The purpose of this study was to determine if corpus cavernosum smooth muscle expresses functional postsynaptic alpha2-adrenoceptors (AR). 2. The alpha2-adrenoceptor agonist UK 14,304 elicited concentration-dependent contractions in rabbit corpus cavernosum smooth muscle (CCSM). The half-maximal response occurred at 0.32+/-0.03 microM and the maximum contraction at 10 microM UK 14,304. 3. Pretreatment of CCSM strips with selective alpha2-adrenoceptor antagonists, rauwolscine and RS-15385, produced rightward shifts in the dose-response curves to UK 14,304 (pA2 values 7.1 and 8.5, respectively). In contrast, these antagonists did not alter contraction induced by the alpha1-adrenoceptor agonist phenylephrine (PE) or oxymetazoline. UK 14,304-induced contractions were also inhibited by prazosin (pA2 = 9.08). 4. UK 14,304-induced contractions, unlike those to PE, were highly dependent on the presence of extracellular Ca2+. 5. [3H]-rauwolscine bound to CCSM membranes with high affinity (Kd = 1.5 nM). [3H]-rauwolscine binding was displaced by unlabelled rauwolscine, RS-15385, UK 14,304 and prazosin, but not by PE. 6. UK 14,304 inhibited forskolin and prostaglandin E1 (PGE1)-induced increases in intracellular cyclic AMP concentration in primary cultures of rabbit CCSM cells. 7. These results demonstrate that CCSM expresses Gi-coupled postsynaptic alpha2-adrenoceptors, and activation of these receptors causes contraction of trabecular smooth muscle.

Phentolamine mesylate relaxes penile corpus cavernosum tissue by adrenergic and non-adrenergic mechanisms.

AIM OF THE STUDY: We investigated the biochemical and physiological mechanisms of action of phentolamine mesylate (Vasomax) in regulating erectile tissue smooth muscle contractility in human and rabbit corpus cavernosum. METHODS: The binding activity of phentolamine was investigated in a cell-free system by displacement of specific and selective radiolabelled ligands to alpha 1 and 2 adrenergic receptors. The physiologic activity of phentolamine-mediated relaxation of adrenergic and non-adrenergic pre-contracted erectile tissue strips of human and rabbit corpus cavernosum were studied in organ bath chambers. RESULTS: In corpus cavernosum membranes, phentolamine displaced binding of the selective alpha 1 receptor antagonists [125I]HEAT and [3H]prazosin and the alpha 2 receptor antagonists [3H]rauwolscine and [3H]RX 821002 with relatively high affinity. Phentolamine caused concentration dependent relaxation in erectile tissue strips pre-contracted with adrenergic agonists phenylephrine, norepinephrine, oxymetazoline and UK 14,304, as well as with non-adrenergic contractile agents endothelin and KCl. Biochemical and physiologic studies reveal that the concentration of phentolamine required to displace half maximal binding or to produce half-maximal relaxation was similar to that found in human plasma 30 min after ingestion of 40 mg of Vasomax. Reversible inhibition of nitric oxide synthase by L-nitroarginine or mechanical disruption of endothelium diminished non-adrenergic phentolamine-mediated erectile tissue relaxation. CONCLUSIONS: Phentolamine mesylate induced relaxation of corpus cavernosum erectile tissue by direct antagonism of alpha 1 and 2 adrenergic receptors and by indirect functional antagonism via a non-adrenergic, endothelium-mediated mechanism suggesting nitric oxide synthase activation.

[Drug-induced fever caused by hydroxyurea. Apropos of 3 new cases]. / Fièvre médicamenteuse induite par l'hydroxyurée. A propos de trois nouveaux cas.

Drug-induced fever is a frequent (3-5% of all adverse effects) but under recognized adverse effect of several drugs. Hydroxyurea, an antimetabolite cytostatic agent, has rarely been involved in the occurrence of fever. We report three additional cases of hydroxyurea-induced fever including one case with pulmonary involvement (acute alveolitis). In these cases, the role of hydroxyurea was strongly suggested by the delay to onset of symptoms (16-36 days), the disappearance of fever within a few hours after drug withdrawal, the recurrence of fever shortly after rechallenge in two patients, and the absence of any other obvious cause.

Treatment of intrathecal morphine-induced pruritus following caesarean section.

PURPOSE: To compare both the efficacy and cost of nalbuphine and diphenhydramine in the treatment of intrathecal morphine-induced pruritus following Caesarean section. METHODS: Eighty patients, undergoing elective Caesarean section under spinal anaesthesia, were randomized, in a prospective, double-blind trial, to receive either nalbuphine (Group NAL) or diphenhydramine (Group DIP) for the treatment of SAB morphine-induced pruritus. All patients received an intrathecal injection of 10-12 mg hyperbaric bupivacaine 0.75% and 200 micrograms preservative free morphine. Postoperative pruritus was assessed, using a visual analogue scale (VAS), for 24 hr. Pruritus treatment was administered upon patient request and by a nurse blinded to the treatment given. Patients who failed to respond to three doses of the study drug were deemed treatment failures. Patient satisfaction was assessed with a questionnaire given 24 to 48 hr after surgery. Direct drug costs were calculated based on the pharmacy provision costs as of April 1996. RESULTS: Eighty patients were enrolled and 45 requested treatment for pruritus. Patients treated with NAL (n = 24) were more likely to achieve a VAS score of zero with treatment (83% vs 43%, P < 0.01), had a higher delta VAS following treatment (4 +/- 2 vs 2 +/- 2, P < 0.003), and experienced fewer treatment failures (4% vs 29%, P < 0.04), than those treated with DIP (n = 21). Group NAL patients were also more likely to rate their pruritus treatment as being good to excellent (96% vs 57%, P < 0.004). Direct drug costs were higher for NAL than for DIP ($6.4 +/- 3.1 vs $1.7 +/- 0.7, respectively, P < 0.0001). CONCLUSION: Nalbuphine is more effective than diphenhydramine in relieving pruritus caused by intrathecal morphine and the cost differences are small.