Tuning of superquenching in layered and mixed fluorescent polyelectrolytes.
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Letter↗
Biomedical subjects
R M Jones
Publications and source records attributed to R M Jones.
Transformation of a kappa-opioid receptor antagonist to a kappa-agonist by transfer of a guanidinium group from the 5'- to 6'-position of naltrindole.
The importance of the indole scaffold of GNTI 3 in directing its address (5'-guanidinium group) to associate with the Glu297 residue of the kappa-opioid receptor was investigated by the synthesis and biological evaluation of its 4'- (4a), 6'- (4b), and 7'- (4c) regioisomers. The finding that only the 5'-regioisomer (GNTI) possessed potent kappa-opioid antagonist activity and high affinity at kappa-receptors illustrates the importance of the 5'-position in orienting the guanidinium group to the proper recognition locus (Glu 297) for potent kappa-antagonist activity. The discovery that the 6'-regioisomer of GNTI was a potent kappa-agonist, together with the results of site-directed mutagenesis studies that are consistent with association between the 6'-guanidinium group and Glu297, suggest that the transition from an inactive to an active state of the kappa-receptor involves a conformational change of TM6. We propose that association of the 6'-guanidinium group of 4b with Glu297 promotes axial rotational motion of transmembrane helix VI which leads to receptor activation via a conformational change of inner loop 3.
Animals↗
A mild anionic method for generating o-quinone methides: facile preparations of ortho-functionalized phenols.
A low-temperature method for generating o-quinone methides is described which permits facile introduction of assorted R substituents onto the aryl ring system at low temperature. The method is useful for the efficient preparation of ortho-ring-alkylated phenols.
Alkylating Agents↗
Effect of dexmedetomidine on propofol requirements in healthy subjects.
Dexmedetomidine-propofol pharmacodynamic interaction was evaluated in nine healthy subjects in a crossover design. Dexmedetomidine/placebo was infused using a computer-controlled infusion pump (CCIP) to maintain a pseudo-steady-state plasma concentration of 0.66 +/- 0.080 or 0 ng/mL, respectively. Forty-five minutes after the dexmedetomidine/placebo infusion was started, propofol was infused using a second CCIP to achieve a stepwise logarithmically ascending propofol concentration (1.00 to 13.8 microg/mL) profile. Each propofol step lasted 10 min. Blood was sampled for plasma concentration determination, and pharmacodynamic endpoint assessments were made during the study. Propofol and dexmedetomidine/placebo infusions were terminated when three endpoints (subjects were too sedated to hold a syringe, followed by loss of eyelash reflex, followed by loss of motor response to electrical stimulation) were achieved sequentially. The concentration of propofol associated with 50% probability of achieving a pharmacodynamic endpoint in the absence of dexmedetomidine (EC50; placebo treatment) was 6.63 microg/mL for motor response to electrical stimulation and ranged from 1.14 to 1.98 microg/mL for the ability to hold a syringe, eyelash reflex, and sedation scores. The apparent EC50 values of propofol (EC50APP; concentration of propofol at which the probability of achieving a pharmacodynamic endpoint is 50% in the presence of dexmedetomidine concentrations observed in the current study; dexmedetomidine treatment) were 0.273, 0.544-0.643, and 3.89 microg/mL for the ability to hold a syringe, sedation scores, and motor response, respectively. Dexmedetomidine reduced propofol concentrations required for sedation and suppression of motor response. Therefore, the propofol dose required for sedation and induction of anesthesia may have to be reduced in the presence of dexmedetomidine.
Adolescent↗
Cone venom--from accidental stings to deliberate injection.
Cone snails have long been of note due to their colorful shells and deadly venom. Over the years, a number of people who have encountered these molluscs have been injured or killed by their sting. Biochemical analysis of the venom components has revealed a plethora of peptides and proteins that target a variety of receptors and ion channels. Pharmaceutical companies are now utilizing the selectivity and potency of Conus-derived peptides to develop novel medications for pain, epilepsy and other disorders.
Animals↗
Antibody-based sensors for heavy metal ions.
Competitive immunoassays for Cd(II), Co(II), Pb(II) and U(VI) were developed using identical reagents in two different assay formats, a competitive microwell format and an immunosensor format with the KinExA 3000. Four different monoclonal antibodies specific for complexes of EDTA-Cd(II), DTPA-Co(II), 2,9-dicarboxyl-1,10-phenanthroline-U(VI), or cyclohexyl-DTPA-Pb(II) were incubated with the appropriate soluble metal-chelate complex. In the microwell assay format, the immobilized version of the metal-chelate complex was present simultaneously in the assay mixture. In the KinExA format, the antibody was allowed to pre-equilibrate with the soluble metal-chelate complex, then the incubation mixture was rapidly passed through a microcolumn containing the immobilized metal-chelate complex. In all four assays, the KinExA format yielded an assay with 10-1000-fold greater sensitivity. The enhanced sensitivity of the KinExA format is most likely due to the differences in the affinity of the monoclonal antibodies for the soluble versus the immobilized metal-chelate complex. The KinExA 3000 instrument and the Cd(II)-specific antibody were used to construct a prototype assay that could correctly assess the concentration of cadmium spiked into a groundwater sample. Mean analytical recovery of added Cd(II) was 114.25+/-11.37%. The precision of the assay was satisfactory; coefficients of variation were 0.81-7.77% and 3.62-14.16% for within run and between run precision, respectively.
Antibodies, Monoclonal↗
Randomized clinical trial comparing totally extraperitoneal inguinal hernia repair with the Shouldice technique.
BACKGROUND: The optimal technique for inguinal hernia repair remains contentious. This study compared the Shouldice repair with the totally extraperitoneal endoscopic (TEP) method in a randomized clinical trial, with quality of life (QoL) and cost analysis. METHODS: Two hundred patients were randomized to Shouldice or TEP repair. Patients were assessed after operation by questionnaire to determine operative outcomes, complications, QoL, and return to work and normal lifestyle. RESULTS: There were 117 TEP and 115 Shouldice repairs. Median operating time was longer for TEP repair (70 versus 56 min; P = 0.0001), but patients were discharged earlier (68 versus 48 per cent within 1 day; P = 0.0065), and had a quicker return to work (14 versus 30 days; P = 0.0001) and normal lifestyle (21 versus 35 days; P = 0.0001). Open repair was nearly 40 per cent cheaper. Late follow-up in 171 patients (86 per cent) at a median of 1.3 years found that TEP repair led to fewer complications at 1 year (9 versus 21 per cent; P = 0.05) and was associated with significant improvement for the QoL components of work performance and satisfaction, physical symptoms and sense of well-being. CONCLUSION: TEP repair results in fewer complications and an earlier return to work and normal lifestyle, but is more expensive and takes longer to perform.
Costs and Cost Analysis↗
areCBA is an operon in Acinetobacter sp. strain ADP1 and Is controlled by AreR, a sigma(54)-dependent regulator.
The areCBA genes in Acinetobacter sp. strain ADP1, determining growth on benzyl alkanoates, are shown to be transcribed as a single operon and regulated by areR, which encodes a regulatory protein of the NtrC/XylR family. Assays of the Are enzymes and of two insertions of lacZ as a reporter gene have shown that the operon is induced by benzyl acetate, benzyl alcohol, and benzaldehyde, as well as 2- and 4-hydroxybenzyl acetates and benzyl propionate and butyrate. Two adjacent sites of transcriptional initiation were 97 and 96 bp upstream of the start codon for areC, near a sigma(54)-dependent -12, -24 promoter. Inactivation of areR and rpoN (for RNA polymerase sigma(54)) drastically reduced growth rates on the Are substrates and induction of the operon.
Acinetobacter↗
The hepatic artery: a reminder of surgical anatomy.
This study was carried out to document the anatomy of the hepatic artery with the purpose of reminding surgeons of the need for this essential knowledge in order to practice safe hepatobiliary surgery. Repeated surgical mistakes on patients referred to our unit prompted the study. One hundred and eighty consecutive livers procured for transplantation was studied, and the anatomy drawn immediately after dissection. The left hepatic artery arose from the left gastric artery in 15%, and either the splenic, gastroduodenal artery or the aorta in 4% of cases. The right hepatic artery arose from the superior mesenteric artery in 15%, the gastroduodenal, right gastric artery or aorta in 10% of cases. There was a major variation of the coeliac axis in 9% of cases studied. Overall, there was an abnormality in 43% of dissections: 48% were multiple and 27% had more than two vascular variations. A constant pattern of abnormalities occurred in the anatomy of the hepatic artery. Realisation of this vascular pattern should make identification of the anatomy easier. When there is one vascular variation, there is a high chance of there being multiple variations.
Adolescent↗
Potent and selective indolomorphinan antagonists of the kappa-opioid receptor.
The indole moiety in the delta-opioid antagonist, naltrindole (2, NTI), was employed as a scaffold to hold an "address" for interaction with the kappa-opioid receptor. The attachment of the address to the 5'-position of the indole moiety was based on superposition of NTI upon the kappa antagonist, norbinaltorphimine (1, norBNI). A variety of cationic groups were employed as a kappa address in an effort to investigate its interaction with the anionic address subsite, Glu297, on the kappa receptor. Some of the groups that were employed for this purpose were amines, amidines, guanidines, and quaternary ammonium. Members of the series were found to have a varying degree of kappa antagonist potency and kappa selectivity when tested in smooth muscle preparations. The 5'-guanidine derivative 12a (GNTI) was the most potent member of the series and had the highest kappa selectivity ratio. GNTI was 2 times more potent and 6-10-fold more selective than norBNI (1). In general, the order of potency in the series was: guanidines > amidines approximately quaternary ammonium > amines. The kappa antagonist potency appeared to be a function of a combination of the pK(a) and distance constraint of the cationic substituent of the ligand. Receptor binding studies were qualitatively in agreement with the pharmacological data. Molecular modeling studies on 12a suggested that the protonated N-17 and guanidinium groups of GNTI are associated with Asp138 (TM3) and Glu297 (TM6), respectively, while the phenolic hydroxyl may be involved in donor-acceptor interactions with the imidazole ring of His291. It was concluded that the basis for the high kappa selectivity of GNTI is related both to association with the nonconserved Glu297 residue and to unfavorable interactions with an equivalent position in mu- and delta-opioid receptors.
Cell Line↗
5'-Guanidinonaltrindole, a highly selective and potent kappa-opioid receptor antagonist.
5'-Guanidinonaltrindole (GNTI) possesses 5-fold greater opioid antagonist potency (K(e)=0.04 nM) and an order of magnitude greater selectivity (selectivity ratios >500) than the prototypical kappa-opioid receptor antagonist, norbinaltorphimine, in smooth muscle preparations. Binding and functional studies conducted on cloned human opioid receptors expressed in Chinese hamster ovarian (CHO) cells afforded pA(2) values that were comparable to the smooth muscle data. In view of the high selectivity and potency of GNTI, it is a potentially valuable pharmacological tool for opioid research.
Animals↗
Binding of norbinaltorphimine (norBNI) congeners to wild-type and mutant mu and kappa opioid receptors: molecular recognition loci for the pharmacophore and address components of kappa antagonists.
Molecular modifications of both the kappa opioid antagonist norbinaltorphimine (norBNI, 1) and the kappa receptor have provided evidence that the selectivity of this ligand is conferred through ionic interaction if its N17' protonated amine group (an "address") with a nonconserved acidic residue (Glu297) on the kappa receptor. In the present study, we have examined the effect of structural modifications on the affinity of norBNI analogues for wild-type and mutant kappa and mu opioid receptors expressed in COS-7 cells. Compounds 2, 3, and 7, which have an antagonist pharmacophore and basic N17' group in common with norBNI, retained high affinity for the wild-type kappa but exhibited greatly reduced affinity for mutant kappa receptors (E297K and E297A). Modification of the phenolic or N-substituent groups of the antagonist pharmacophore (4 and 5) or removal of basicity at the address N17' center (6) led to greatly reduced affinity for the wild-type and mutant receptors. The reduced affinity upon modification of the kappa receptor is consistent with the ionic interaction of the protonated N17' group of kappa antagonists (1-3, 7) with the carboxylate group of E297 at the top of TM6. This was supported by the greatly enhanced affinity of compounds 1-3 for the mutant mu receptor (K303E), as compared to the wild-type mu receptor, given that residue K303 occupies a position equivalent to that of E297 in the kappa receptor. In view of the high degree of homology of the seven TM domains of the kappa and mu opioid receptors, it is suggested that the antagonist pharmacophore is bound within this highly conserved region of the kappa or mutant mu receptor and that an anionic residue at the top of TM6 (E297 or K303E, respectively) provides additional binding affinity.
Amino Acid Substitution↗
Investigation of phenolic bioisosterism in opiates: 3-sulfonamido analogues of naltrexone and oxymorphone.
[formula: see text] The phenolic hydroxy group of opiate-derived ligands is of known importance for biological activity. On the basis of its putative role as a hydrogen-bonding donor in the interaction with opioid receptors, it was replaced with a sulfonamide group because of their similar pKa values. The first thebaine-derived 3-amino (8a, 8b) and subsequent sulfonamide analogues (10a, 10b) were synthesized from naltrexone (1a) and oxymorphone (1b) in a linear nine-step synthesis. The sulfonamides were tested in vitro and found inactive.
Indicators and Reagents↗
Temporal lobe injury in temporal bone fractures.
OBJECTIVE: To determine the incidence of intracranial injury, specifically in the temporal lobe, in patients with longitudinal fractures of the temporal bone. DESIGN: Prospective inception cohort. SETTING: University of Maryland Division of Otolaryngology-Head and Neck Surgery and the Maryland Shock Trauma Center, Baltimore. PATIENTS: Twenty-seven consecutive patients with unilateral or bilateral temporal bone fractures. MAIN OUTCOME MEASURES: Evaluation of temporal bone and intracranial trauma using computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: Of the 27 patients enrolled in the study, 12 had the complete battery of MRI, CT, and physical and audiological examinations. In all 12 patients, MRI demonstrated adjacent middle cranial fossa meningeal enhancement. Results of non-contrast-enhanced CT and MRI demonstrated ipsilateral temporal lobe contusions in 6 of the 13 fractures for an overall incidence of 46%. In addition, MRI demonstrated 4 cerebral contusions not seen in the results of non-contrast-enhanced CT. CONCLUSIONS: While high-resolution CT remains the criterion standard for evaluation of temporal bone fractures, MRI revealed a higher incidence of related temporal lobe injuries. Magnetic resonance imaging data may be valuable in preoperative evaluation of patients who require surgical intervention through a middle cranial fossa approach to document pre-existing injury and potential morbidity before retraction of the middle cranial fossa dura mater and temporal lobe.
Adolescent↗
sal genes determining the catabolism of salicylate esters are part of a supraoperonic cluster of catabolic genes in Acinetobacter sp. strain ADP1.
A 5-kbp region upstream of the are-ben-cat genes was cloned from Acinetobacter sp. strain ADP1, extending the supraoperonic cluster of catabolic genes to 30 kbp. Four open reading frames, salA, salR, salE, and salD, were identified from the nucleotide sequence. Reverse transcription-PCR studies suggested that these open reading frames are organized into two convergent transcription units, salAR and salDE. The salE gene, encoding a protein of 239 residues, was ligated into expression vector pET5a. Its product, SalE, was shown to have esterase activity against short-chain alkyl esters of 4-nitrophenol but was also able to hydrolyze ethyl salicylate to ethanol and salicylic acid. A mutant of ADP1 with a Km(r) cassette introduced into salE had lost the ability to utilize only ethyl and methyl salicylates of the esters tested as sole carbon sources, and no esterase activity against ethyl salicylate could be detected in cell extracts. SalE was induced during growth on ethyl salicylate but not during growth on salicylate itself. salD encoded a protein of undetermined function with homologies to the Escherichia coli FadL membrane protein, which is involved in facilitating fatty acid transport, and a number of other proteins detected during aromatic catabolism, which may also function in hydrocarbon transport or uptake processes. A Km(r) cassette insertion in salD deleteriously affected cell growth and viability. The salA and salR gene products closely resemble two Pseudomonas proteins, NahG and NahR, respectively encoding salicylate hydroxylase and the LysR family regulator of both salicylate and naphthalene catabolism. salA was cloned into pUC18 together with salR and salE, and its gene product showed salicylate-inducible hydroxylase activity against a range of substituted salicylates, with the same relative specific activities as found in wild-type ADP1 grown on salicylate. Mutations involving insertion of Km(r) cassettes into salA and salR eliminated expression of salicylate hydroxylase activity and the ability to grow on either salicylate or ethyl salicylate. Studies of mutants with disruptions of genes of the beta-ketoadipate pathway with or without an additional salE mutation confirmed that ethyl salicylate and salicylate were channeled into the beta-ketoadipate pathway at the level of catechol and thence dissimilated by the cat gene products. SalR appeared to regulate expression of salA but not salE.
Acinetobacter↗
Conotoxins - new vistas for peptide therapeutics.
There are approximately 500 species of predatory cone snails within the genus Conus. They comprise what is arguably the largest single genus of marine animals alive today. It has been estimated that the venom of each Conus species has between 50 and 200 components. These highly constrained sulfur rich components or conotoxins represent a unique arsenal of neuropharmacologically active peptides that have been evolutionarily tailored to afford unprecedented and exquisite selectivity for a wide variety of ion-channel subtypes. Remarkable divergence occurs when cone snails speciate. Consequently, the complement of venom peptides in any one Conus species is distinct from that of any other species. Hence many thousands of peptides that modulate ion channel function are present within Conus venoms. Evolutionary pressures have afforded a "pre-optimized," structurally sophisticated library that has been "fine tuned" over 50 million years. The statistics associated with sampling such libraries bear testimony to the validity and feasibility of this strategy. Although approximately 100 conotoxin sequences have been published in the scientific literature, representing a mere 0.2 % of the estimated library size, this sample has already afforded a peptide of proven clinical utility and several pre-clinical leads for CNS disorders. Conus libraries represent a rich pharmacopoeia and the potential to "therapeutically mine" such a resource appears limitless. The paucity of synthetic methodologies necessary to achieve the regioisomeric folding patterns present in these native peptides precludes access to synthetic conotoxin libraries, further validating the overall "mining" strategy. In this article, we will present a pragmatic overview of the molecular diversity as well as the neurobiological mechanisms that define each major class of conotoxin.
Amino Acid Motifs↗
Lumbar epidurals via the midline approach.
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Analgesia, Epidural↗
In vivo uptake of radiolabeled antibody to proliferating smooth muscle cells in a swine model of coronary stent restenosis.
UNLABELLED: Z2D3 is a monoclonal chimeric antibody fragment that is directed against a protein expressed on the surface of proliferating smooth muscle cells. The purpose of this study was to investigate the uptake of 111In-labeled Z2D3 F(ab')2 in a swine model of coronary neointimal proliferation after overexpansion coronary stenting. METHODS: Twenty-two domestic swine underwent overexpansion coronary stenting of 2 vessels. Fifteen swine survived 2-4 wk, at which time they received an injection of 111In Z2D3 F(ab')2 and underwent planar imaging. After the swine were killed, the hearts were excised and imaged on the detector. The cross-sectional area of each stented vessel was measured with digital morphometry. RESULTS: Pathology could be correlated with imaging for 24 vessels. The cross-sectional area of stenosis comprising neointimal proliferation ranged from 8% to 95%, with a mean +/- SD of 41% +/- 21%. The maximal stenosis ranged from 13% to 95%, with a mean of 51% +/- 20%. Seventeen of 24 vessels (71%) showed focal uptake on in vivo imaging, and 7 of 24 (29%) did not. Twenty of 24 (83%) showed uptake on ex vivo imaging. Of 11 stented vessels with maximal vessel stenosis less than 50%, 7 (64%) showed uptake both in vivo and ex vivo, and of 13 stented vessels with maximal vessel stenosis greater than 50%, 10 (77%) showed uptake both in vivo and ex vivo. CONCLUSION: Uptake of a radiolabeled antibody directed against a component of proliferating neointimal tissue can be visualized in the coronary arteries on in vivo imaging using a scintillation gamma camera.
Animals↗