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R Murphy

Publications and source records attributed to R Murphy.

At least 73 records · Page 4Linked to original sources
PubMed1999

Roles of key functional groups in omega-conotoxin GVIA synthesis, structure and functional assay of selected peptide analogues.

The contributions of various functional groups to the pharmacophore of the N-type calcium-channel blocker, omega-conotoxin GVIA (GVIA), have been investigated using structural and in-vitro functional studies of analogues substituted at one or two positions with non-native residues. In most cases the structure of the analogue was shown to be native-like by 1H NMR spectroscopy. Minor conformational changes observed in some cases were characterized by two-dimensional NMR. Three functional assays (sympathetic nerve stimulation of rat isolated vas deferens, right atrium and mesenteric artery) were employed to monitor N-type calcium-channel activity. The data provide a more detailed picture of the roles in GVIA structure and activity of the crucial Lys2 and Tyr13, as well as all other positively charged residues, Tyr22, the hydroxyproline residues and the C-terminal amido moiety, many of which were identified as being important for activity in an alanine scan [Lew et al. (1997) J. Biol. Chem. 272, 12014-12023]. Substitutions of Lys2 with nonstandard amino acids and arginine quantified the roles of the length and charge of the Lys side chain. The orientation of the Tyr13 side chain and its hydroxyl moiety was shown to be important by substitution with d-Tyr and the d-form and l-form of the constrained analogue 7-hydroxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid [Tic(OH)]. The roles of the Hyp10 and Hyp21 hydroxyl groups, investigated by proline substitutions, appear to be more structural (as monitored by NMR) than functional, although small decreases in potency were observed in some assays. The reversibility of the channel blockade was also studied, and several analogues with faster wash-out characteristics than native GVIA were identified. Rapid reversibility (as in the case of omega-conotoxin MVIIA) may be beneficial for therapeutic applications. Disubstituted analogues revealed some interesting cooperative effects, which were not predicted from single-residue substitutions. A disubstituted chimera of GVIA and omega-conotoxin MVIIA was more potent than either native molecule. The more detailed description of the GVIA pharmacophore obtained here provides a better basis for the future design of truncated peptide and peptidomimetic analogues.

Amino Acid Sequence↗
PubMed1999

Predicting 3-day and 7-day outcomes of weaning from mechanical ventilation.

OBJECTIVE: To determine the correlation of acute physiology and chronic health evaluation (APACHE) II score and various weaning indexes (WIs) with 3- and 7-day weaning outcomes. DESIGN: Prospective, observational. SETTING: The medical ICU of a teaching, urban hospital. METHODS: The study included 118 adults referred for weaning from mechanical ventilation (MV). Critical care physicians, critical care nurses, and respiratory care practitioners were asked to predict whether it would take < or =3 days, 4 to 7 days, or > or =8 days to wean each patient from MV. The WIs and APACHE II scores were measured or calculated. The causes of respiratory failure, the duration of MV before initiating weaning assessment, and the 3- and 7-day weaning outcomes were obtained. Significance was set at p<0.05. RESULTS: The most common causes of respiratory failure were pneumonia (38 cases) and acute exacerbation of COPD (29 cases). Fifty-seven patients (48%) were successfully weaned from MV within 3 days of weaning assessment, and 67 (57%) were weaned within 7 days. The percentages of correct prediction of 3-day weaning outcome by critical care physicians, critical care nurses, and respiratory care practitioners were 64%, 62%, and 59%, respectively; for 7-day weaning outcome, 60%, 64%, and 58%, respectively. The successfully weaned groups had significantly lower APACHE II scores and higher maximal inspiratory pressures than the unsuccessfully weaned (failure) groups. There were no significant differences between the two groups for the remaining indexes, including rapid shallow breathing, dynamic compliance, static compliance, spontaneous respiratory rate, and the ratio of PaO2 to the fraction of inspired oxygen. CONCLUSIONS: The overall severity of illness as assessed by APACHE II score correlates better with 3- and 7-day weaning outcome than the published WIs.

APACHE↗
PubMed1998

The human homologue of Saccharomyces cerevisiae Gle1p is required for poly(A)+ RNA export.

The mechanism of mRNA export is a complex issue central to cellular physiology. We characterized previously yeast Gle1p, a protein with a leucine-rich (LR) nuclear export sequence (NES) that is essential for poly(A)+ RNA export in Saccharomyces cerevisiae. To characterize elements of the vertebrate mRNA export pathway, we identified a human homologue of yeast Gle1p and analyzed its function in mammalian cells. hGLE1 encodes a predicted 75-kDa polypeptide with high sequence homology to yeast Gle1p, but hGle1p does not contain a sequence motif matching any of the previously characterized NESs. hGLE1 can complement a yeast gle1 temperature-sensitive export mutant only if a LR-NES is inserted into it. To determine whether hGle1p played a role in nuclear export, anti-hGle1p antibodies were microinjected into HeLa cells. In situ hybridization of injected cells showed that poly(A)+ RNA export was inhibited. In contrast, there was no effect on the nuclear import of a glucocorticoid receptor reporter. We conclude that hGle1p functions in poly(A)+ RNA export, and that human cells facilitate such export with a factor similar to yeast but without a recognizable LR-NES. With hGle1p localized at the nuclear pore complexes, hGle1p is positioned to act at a terminal step in the export of mature RNA messages to the cytoplasm.

Amino Acid Sequence↗
PubMed1998

Activation of neurokinin 1 receptors on interstitial cells of Cajal of the guinea-pig small intestine by substance P.

The aims of this work were to determine whether cells that are similar to the interstitial cells of Cajal (ICC) and have immunoreactivity for the neurokinin 1 (NK1) receptor are indeed ICC; to determine whether the agonist, substance P, binds to and activates the receptor on presumptive ICC; and to investigate the relationship between substance P-immunoreactive nerve fibres and ICC. ICC at the level of the myenteric plexus and in the deep muscular plexus in the duodenum and ileum of the guinea-pig were investigated. Immunoreactivities for the ICC marker, Kit, and the NK1 receptor were colocalised in ICC of the myenteric and deep muscular plexuses. In tissue fixed immediately after its removal from the animal, NK1 receptor-immunoreactive ICC were found at the level of the myenteric plexus in the duodenum, but not in the ileum, and in the deep muscular plexus in the duodenum and ileum. The majority of receptor immunoreactivity was on the cell surface. ICC were exposed to substance P (10(-7) M), initially at 4 degrees C for 1 h to allow the agonist to bind, followed by incubation at 37 degrees C to allow receptor internalisation to proceed. Exposure to substance P caused the NK1 receptor immunoreactivity to aggregate in clumps in the cytoplasm of ICC of the myenteric and deep muscular plexuses, including the ICC of the myenteric plexus of the ileum, where NK1 receptor immunoreactivity was not seen if tissue was not exposed to substance P. Substance P, to which the fluorescent label, cyanine 3.18 (Cy-3), was coupled, bound to the ICC. The Cy-3-substance P was internalised with the receptor following warming to 37 degrees C. Many, but not all, ICC were closely apposed by nerve fibres with immunoreactivity for substance P. It is concluded that the NK1 receptor immunoreactivity on ICC represents receptor that is functional in the sense that it binds the natural agonist substance P and undergoes agonist-induced internalisation. ICC are likely to receive excitatory innervation from the close approaches of tachykinin-containing nerve fibres.

Animals↗
PubMed1998

Etiology and response to drug treatment in heart failure.

Clinical trials in heart failure (HF) tend to randomize patients according to demographic characteristics and severity of left ventricular dysfunction, without taking account of the precise diagnosis. This article reviews results from recent trials suggesting that the etiology of HF, and particularly whether it is ischemic or nonischemic, may influence the long-term prognosis and the response to treatment. Some studies, but not all, suggest that nonischemic HF has a better prognosis than ischemic HF. The data on the benefits of angiotensin-converting enzyme inhibitors in ischemic versus nonischemic HF are conflicting. Carvedilol, and recently, bisoprolol have been shown to reduce mortality in ischemic and nonischemic HF, whereas metoprolol has, to date, improved prognosis only in dilated cardiomyopathy. Better responses to digoxin, amlodipine and amiodarone have been reported in non-ischemic HF. There is at present no clear explanation for the apparent therapeutic differences between ischemic and nonischemic HF. Absence of a rigorous definition of "nonischemic HF" in many studies makes interpretation of the results difficult. Further studies to clarify the effects of etiology of HF on the response to treatment could be particularly important for preventing progression to more advanced stages, in which any type of drug therapy may have limited value in prolonging survival. An individualized therapeutic approach, based on etiology of HF and possibly other factors such as plasma drug levels or the levels of neurohormones, could result in major progress in treating HF patients.

Adrenergic beta-Antagonists↗
PubMed1998

Pharmacokinetics of the protease inhibitor KNI-272 in plasma and cerebrospinal fluid in nonhuman primates after intravenous dosing and in human immunodeficiency virus-infected children after intravenous and oral dosing.

KNI-272 is a human immunodeficiency virus (HIV) protease inhibitor with potent activity in vitro. We studied the pharmacokinetics of KNI-272 in the plasma and cerebrospinal fluid (CSF) of a nonhuman primate model and after intravenous and oral administration to children with HIV infection. Plasma and CSF were sampled over 24 h after the administration of an intravenous dose of 50 mg of KNI-272 per kg of body weight (approximately 1,000 mg/m2) to three nonhuman primates. The pharmacokinetics of KNI-272 were also studied in 18 children (9 males and 9 females; median age, 9.4 years) enrolled in a phase I trial of four dose levels of KNI-272 (100, 200, 330, and 500 mg/m2 per dose given four times daily). The plasma concentration-time profile of KNI-272 in the nonhuman primate model was characterized by considerable interanimal variability and rapid elimination (clearance, 2.5 liters/h/kg; terminal half-life, 0.54 h). The level of drug exposure achieved in CSF, as measured by the area under the KNI-272 concentration-time curve, was only 1% of that achieved in plasma. The pharmacokinetics of KNI-272 in children were characterized by rapid elimination (clearance, 276 ml/min/m2; terminal half-life, 0.44 h), limited (12%) and apparently saturable bioavailability, and limited distribution (volume of distribution at steady state, 0.11 liter/kg). The concentrations in plasma were maintained above a concentration that is active in vitro for less than half of the 6-h dosing interval. There was no significant increase in CD4 cell counts or decrease in p24 antigen or HIV RNA levels. The pharmacokinetic profile of KNI-272 may limit the drug's efficacy in vivo. It appears that KNI-272 will play a limited role in the treatment of HIV-infected children.

Administration, Oral↗
PubMed1997

Structure-function relationships of omega-conotoxin GVIA. Synthesis, structure, calcium channel binding, and functional assay of alanine-substituted analogues.

The structure-function relationships of the N-type calcium channel blocker, omega-conotoxin GVIA (GVIA), have been elucidated by structural, binding and in vitro and in vivo functional studies of alanine-substituted analogues of the native molecule. Alanine was substituted at all non-bridging positions in the sequence. In most cases the structure of the analogues in aqueous solution was shown to be native-like by 1H NMR spectroscopy. Minor conformational changes observed in some cases were characterized by two-dimensional NMR. Replacement of Lys2 and Tyr13 with Ala caused reductions in potency of more than 2 orders of magnitude in three functional assays (sympathetic nerve stimulation of rat isolated vas deferens, right atrium and mesenteric artery) and a rat brain membrane binding assay. Replacement of several other residues with Ala (particularly Arg17, Tyr22 and Lys24) resulted in significant reductions in potency (<100-fold) in the functional assays, but not the binding assay. The potencies of the analogues were strongly correlated between the different functional assays but not between the functional assays and the binding assay. Thus, the physiologically relevant assays employed in this study have shown that the high affinity of GVIA for the N-type calcium channel is the result of interactions between the channel binding site and the toxin at more sites than the previously identified Lys2 and Tyr13.

Alanine↗
PubMed1997

Clinical efficacy of monotherapy with stavudine compared with zidovudine in HIV-infected, zidovudine-experienced patients. A randomized, double-blind, controlled trial. Bristol-Myers Squibb Stavudine/019 Study Group.

BACKGROUND: Stavudine is a promising antiretroviral agent, but its clinical efficacy has not been determined. OBJECTIVE: To evaluate the clinical effect of stavudine (2',3'-didehydro-3'-deoxythymidine) monotherapy in patients with human immunodeficiency virus (HIV) infection. DESIGN: Randomized, controlled, double-blind trial. SETTING: 56 outpatient clinics in private practices, universities, and contract research organizations in the United States, France, and Italy. PATIENTS: 822 HIV-infected adults who had 50 to 500 CD4+ cells/mm3 and had previously received at least 6 months of zidovudine treatment. INTERVENTION: Monotherapy with peroral stavudine capsules or peroral zidovudine capsules. MEASUREMENTS: The primary end point was clinical progression, which was defined as all occurrences of acquired immunodeficiency syndrome (AIDS)-defining events or death. RESULTS: Patients receiving stavudine reached clinical end points at a rate of 26 per 100 person-years, compared with 32 per 100 person-years for patients receiving zidovudine (relative risk, 0.75 [95% CI, 0.58 to 0.98]; P = 0.03). The risk for death alone was 26% lower in the stavudine group than in the zidovudine group, but the comparison was not statistically significant (relative risk, 0.74 [CI, 0.53 to 1.02]; P = 0.066). The benefit of stavudine therapy was seen in all CD4+ cell strata (< or = 100 cells/mm3, 101 to 300 cells/mm3, and > 300 cells/mm3) and clinical stages of HIV disease (asymptomatic, symptomatic, and AIDS). Four weeks after treatment began, CD4+ cell counts were 30 cells/mm3 higher in the stavudine group than in the zidovudine group; this difference was sustained for 96 weeks (P < 0.001). Nausea and vomiting were more common in patients receiving zidovudine (P < 0.01), and neuropathy occurred more frequently in those receiving stavudine (12% in the stavudine group compared with 4% in the zidovudine group; P < 0.001). Neuropathy resolved completely in many patients (63%) after interruption of stavudine treatment; these patients could resume stavudine therapy at a lower dose. CONCLUSIONS: Stavudine was well tolerated and delayed progression of HIV disease in patients who had previously received 6 or more months of zidovudine treatment. Benefits were apparent in all CD4+ cell strata and clinical stages of HIV disease. Stavudine is an important agent to consider for trials of combination chemotherapy.

Adult↗
PubMed1997

Long-term efficacy and safety of dronabinol for acquired immunodeficiency syndrome-associated anorexia.

We studied the effects of long-term (12 months) dronabinol in 94 late-stage acquired immunodeficiency syndrome (AIDS) patients (mean CD4 count of 45/mm3) who previously participated in a 6-week study (placebo versus dronabinol). All patients received dronabinol orally-2.5 mg twice daily (90%) or 2.5 mg once daily (10%). Appetite was measured using a visual analogue scale for hunger (VASH). Dronabinol was associated with consistent improvement in mean appetite. Patients previously treated with dronabinol continued to show improvement in VASH (percent change from baseline of 6-week trial: 48.6-76.1% at each month), whereas those previously treated with placebo exhibited substantial improvement in mean appetite, particularly during the initial 4 months of treatment (48.5-69.9%). Thereafter, dronabinol was associated with a VASH change at least twice baseline. Patients tended toward stable body weight for at least 7 months. Adverse events were primarily related to known central nervous system effects of dronabinol. These data support long-term, safe use of dronabinol for anorexia associated with weight loss in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Characterization of normal and malignant human hepatocytes by Raman microspectroscopy.

Raman microspectroscopy was used to characterize normal and malignant hepatocytes in both cultured cells and human liver tissues. Consistent spectral changes were observed, including intensity increases at 1040 and 1083 cm(-1) with malignancy. A loss of intensity at 1241 cm(-1) was also observed in cancer cells, but was obscured in tissues by the overlap of a 1253 cm(-1) band, thought to originate from heme proteins. Normal liver tissue also differed from both the malignant tumor and its accompanying cirrhotic tissue at 1182 cm(-1). These results demonstrate the potential usefulness of Raman spectroscopy in clinical diagnosis, and investigations into the source of the observed spectral changes will provide information on the underlying mechanisms of carcinogenesis.

Carcinoma, Hepatocellular↗
PubMed1996

An RNA-export mediator with an essential nuclear export signal.

The Rev protein of human immunodeficiency virus type 1 (HIV-1) mediates the translocation of viral messenger RNAs from the nucleus to the cytoplasm. In yeast, Rev can mediate the nuclear export of Rev response-element-containing RNAs. The export of Rev itself proceeds through the nuclear pore complex and requires a nuclear export signal (NES) and interaction with a cellular cofactor, the protein Rip1. Endogenous RNA export mediators that interact with Rip1 and harbour NESs are thought to exist but have yet to be identified. Here we report the characterization of a new and essential yeast protein, Gle1, which contains an NES and has a relative molecular mass of 62,000. Mutation of the NES in Gle1 prevents export of polyadenylated RNA from the nucleus. Gle1 interacts with Rip1 and the nucleoporin Nup100 and is localized predominantly at nuclear pore complexes. These properties indicate that Gle1 is an RNA-export factor and that Rev may mediate viral RNA export by mimicking the function of Gle1.

Amino Acid Sequence↗
PubMed1996

Activation of tyrosine hydroxylase by pituitary adenylate cyclase-activating polypeptide (PACAP-27) in bovine adrenal chromaffin cells.

The effect of pituitary adenylate cyclase-activating polypeptide (PACAP-27) on tyrosine hydroxylase activity has been studied in intact, cultured, bovine adrenal chromaffin cells. Tyrosine hydroxylase activity was determined in situ by measuring the production of 14CO2 following the hydroxylation and rapid decarboxylation of [14C]tyr offered to the cells. PACAP-27 increased tyrosine hydroxylase activity 3-fold over 10 min. With an EC50 of 10-20 nM. PACAP-38 was approximately 2-fold less potent. Removing extracellular Ca2+ reduced basal tyrosine hydroxylase activity and the activation produced by both PACAP-27 and forskolin by about 20%. In the absence of extracellular Ca2+, chelation of intracellular Ca2+ by treating cells with BAPTA-AM (50 microM) caused a consistent 40-50% reduction in basal tyrosine hydroxylase activity and in the responses to forskolin and PACAP-27. The tyrosine hydroxylase activation produced by PACAP-27 was unaffected by the protein kinase C inhibitor Ro 3l-8220 (3 microM), but was reduced by 85% by the protein kinase A inhibitor H89 (10 microM). PACAP-27 increased cellular cyclic AMP levels 3-fold at 100 nM. The results suggest that PACAP-27 activates tyrosine hydroxylase in bovine chromaffin cells through cyclic AMP formation and protein kinase A activation, and that both extracellular and intracellular Ca2+ modulate the effect of the adenylate cyclase/cyclic AMP/protein kinase A signalling pathway on tyrosine hydroxylase activity.

Animals↗
PubMed1996

Early clinical markers and CD4 percentage in subjects with human immunodeficiency virus infection.

In a clinical trial involving asymptomatic, HIV-seropositive subjects treated with either the HIV-1 immunogen (an inactivated, gp120-depleted HIV-1 virus in incomplete Freund's adjuvant) or an adjuvant control, we examined the relationship between changes in the percentage of CD4 cells over time and early clinical markers of HIV disease progression. Subjects who had an early clinical event were more likely to have a greater decline in the percentage of CD4 cells than those subjects who did not have a clinical event (p = 0.054). The greatest decline in CD4 percentage occurred within 10 weeks prior to a clinical event (mean 11% decrease from baseline). Subjects from the quartile with the greatest decline in CD4 percentage had a fivefold greater risk of having a clinical event than subjects from the quartile with the second largest decline (p = 0.045). These results demonstrate a relationship between changes in the percentage of CD4 cells and early clinical events. Further validation of this association may be useful in clinical monitoring and in evaluating therapies to treat HIV infection.

AIDS Dementia Complex↗
PubMed1996

School-associated violent deaths in the United States, 1992 to 1994.

OBJECTIVES: To conduct the first nationwide investigation of violent deaths associated with schools in the United States, to quantify the risk of school-associated violent death, and to identify epidemiologic features of these deaths. DESIGN: Descriptive case series. SETTING: United States, July 1, 1992, through June 30, 1994. METHODS: School-associated violent deaths were identified by study collaborators and through 2 online news databases. Police reports, medical examiners' records, and interviews with police and school officials provided detailed information about each case. RESULTS: In a 2-year period, 105 school-associated violent deaths were identified. The estimated incidence of school-associated violent death was 0.09 per 100 000 student-years. Students in secondary schools, students of minority racial and ethnic backgrounds, and students in urban school districts had higher levels of risk. The deaths occurred in communities of all sizes in 25 different states. Homicide was the predominant cause of death (n = 85 [80.9%]), and firearms were responsible for a majority (n = 81 [77.1%]) of the deaths. Most victims were students (n = 76 [72.4%]). Both victims and offenders tended to be young (median ages, 16 and 17 years, respectively) and male (82.9% and 95.6%, respectively). Approximately equal numbers of deaths occurred inside school buildings (n = 31 [29.5%]), outdoors but on school property (n = 37 [35.2%]), and at off-campus locations while the victim was in transit to or from school (n = 37 [35.2%]). Equal numbers of deaths occurred during classes or other school activities (n = 46 [43.8%]) and before or after official school activities (n = 46 [43.8%]). CONCLUSIONS: School-associated violent deaths were more common than previously estimated. The epidemiologic features of these deaths were similar to those of homicides and suicides that occur elsewhere. A comprehensive approach that addresses violent injury and death among young people at school and elsewhere in the community is suggested.

Adolescent↗
PubMed1996

Characterisation of substance P-induced endocytosis of NK1 receptors on enteric neurons.

Immunoreactivity for NK1 receptors is confined to specific nerve cell bodies in the guinea-pigileum, including inhibitory motor neurons and secretomotor neurons. In the present work, endocytosis of NK1 receptors in these enteric neurons was studied following addition of substance P (SP) to isolated ileum. NK1 receptors were localised with antibodies against the C-terminus of this receptor. Some preparations were incubated with SP tagged with the fluorescent label, Cy3.18, so that the fate of SP bound to receptors could be followed. Preparations were analysed by confocal microscopy. In tissue that was incubated at 4 degrees C in the absence of SP, most NK1 receptor immunoreactivity (IR) was confined to surface membranes of nerve cells. At 37 degrees C in the presence of 10(-7) M SP (plus 3 x 10(-7)M tetrodotoxin to prevent indirect activation via other neurons) the neuronal NK1 receptor was rapidly internalised. After 5 min, NK1 receptor IR was partially internalised, at 20 min NK1 receptor IR was throughout the cytoplasm and in perinuclear aggregates and at 30 min it was again at the cell surface. SP-induced NK1 receptor endocytosis was inhibited by the specific NK1 receptor antagonist, SR140333. Cy3-SP was colocalised with NK1 receptor IR and was internalised with the NK1 receptor. These results show that enteric neurons exhibit authentic NK1 receptors that are rapidly internalised when exposed to their preferred ligand.

Animals↗
PubMed1996

Peripheral blood eosinophilia, hyperimmunoglobulinemia A and fatigue: possible complications following rupture of silicone breast implants.

BACKGROUND: Silicone breast implantation has been considered quite safe and of major cosmetic value. Immunologic sequelae such as collagen vascular diseases have not been confirmed in large studies. OBJECTIVE: We describe a 55-year-old woman who developed severe fatigue, peripheral blood eosinophilia, and hyperimmunoglobulinemia A after rupture of a silicone breast implant during closed manual manipulation to lyse fibrotic tissue. METHODS: We charted evidence for eosinophilia over a 19-year period and determined quantitative immunoglobulins, and lymphocyte subsets by FACS analysis. RESULTS: Peripheral eosinophilia in 1976 was 693/mm3 and increased to 1360/mm3 after rupture of the implant in 1992. Serum immunoglobulin A was 332 mg/dL in 1976 and ranged after rupture from 473 to 627 mg/dL without other cause. Fatigue was not reversed with a parenteral corticosteroid injection. CD4 and CD8 subsets were normal but 40% of CD3 cells were Ia positive although not CD25 positive (IL2 receptor). Only 5% of B cells were CD19 CD23 positive despite the high concentration of serum IgA. CONCLUSION: This case is an example of a previously unreported apparent adverse effect of silicone-breast implant rupture with persisting eosinophilia, hyperimmunoglobulinemia A, and fatigue.

Breast Implants↗