Search

Purpose: To assess whether open-angle glaucoma (OAG) eyes with choroidal microvasculature dropout (CMvD) have greater severity of glaucomatous damage compared to those eyes without CMvD., Methods: In this retrospective case-control study, 80 eyes of 80 OAG patients with visual field (VF) defects confined to a superior hemifield (40 eyes with CMvD and 40 eyes without CMvD matched for age [≤10 years], axial length [≤1 mm], and VF loss [≤1 dB (decibel)]) and 43 healthy eyes were consecutively included. The circumpapillary retinal nerve fiber layer thickness (cpRNFLT), macular ganglion cell-inner plexiform layer thickness (mGCIPLT), circumpapillary vessel density (cpVD), parafoveal VD (pfVD), and VF mean sensitivity (VFMS) were measured. The relationships between CMvD angular extent and structural/VD/functional measures were assessed at both hemiretinae in OAG eyes with CMvD. Logistic regression analyses were performed to evaluate the associations between significant cpRNFLT reduction at perimetrically intact hemiretinae and relevant clinical variables., Results: Sectoral cpRNFLT and mGCIPLT in the perimetrically intact hemiretinae of eyes with CMvD were significantly lower than those of eyes without CMvD (P < 0.05). There were significant correlations between CMvD angular extent and sectoral measures of structural/VD/functional parameters at perimetrically intact hemiretinae as well as perimetrically affected hemiretinae in OAG eyes with CMvD. The presence and extent of CMvD had a significant influence on cpRNFLT reduction at perimetrically intact hemiretinae (P < 0.05)., Conclusions: OAG eyes with CMvD showed significantly lower cpRNFLT and mGCIPLT than those without CMvD at the hemiretinae corresponding to intact hemifields, thus requiring more vigilant attention for greater disease severity.

Pim kinases are a family of constitutively active serine/threonine kinases that are partially redundant and regulate multiple pathways important for cell growth and survival. In human disease, high expression of the three Pim isoforms has been implicated in the progression of hematopoietic and solid tumor cancers, which suggests that Pim kinase inhibitors could provide patients with therapeutic benefit. Herein, we describe the structure-guided optimization of a series of quinazolinone-pyrrolodihydropyrrolone analogs leading to the identification of potent pan-Pim inhibitor 28 with improved potency, solubility, and drug-like properties. Compound 28 demonstrated on-target Pim activity in an in vivo pharmacodynamic assay with significant inhibition of BAD phosphorylation in KMS-12-BM multiple myeloma tumors for 16 h postdose. In a 2-week mouse xenograft model, daily dosing of compound 28 resulted in 33% tumor regression at 100 mg/kg.

Background: 4D flow MRI is a relatively quick method for obtaining wall shear stress (WSS) in vivo, a hemodynamic parameter which has shown promise in risk stratification for rupture of cerebrovascular diseases such as intracranial aneurysms and atherosclerotic plaques. The accuracy of such measurements is still largely unknown., Objective: To quantify the accuracy of 4D flow MRI-derived wall shear stress values for intracranial aneurysms and carotid bifurcations., Method: We performed a review of all original research articles which compared the magnitudes of WSS derived from 4D flow MRI with corresponding values derived from computational fluid dynamics (CFD) within both intracranial aneurysms and carotid bifurcations., Result: For intracranial aneurysms and carotid bifurcations, 4D flow MRI-derived WSS estimations are generally lower in magnitude compared to WSS derived by CFD methods. These differences are more pronounced in regions of higher WSS. However, the relative distributions of WSS derived from both methods are reasonably similar., Conclusion: Pooled analysis suggests that WSS magnitudes obtained by 4D flow MRI are underestimated, while the relative distribution is reasonably accurate, the latter being an important factor for determining the natural history of intracranial aneurysms and other cerebrovascular diseases. 4D flow MRI shows enormous potential in providing new risk stratification parameters which could have significant impact on individualized treatment decisions and improved patient outcomes., (Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.)

Background: A rarely used technique for enabling closure of large ventral hernias with loss of domain is preoperative progressive pneumoperitoneum (PPP), which uses intermittent insufflation to gradually stretch the contracted abdominal wall muscles, increasing the capacity of the abdominal cavity. This allows the re-introduction of herniated viscera into the abdominal cavity and assists in closure of giant hernias which may otherwise be considered inoperable., Methods: This was a prospective study assessing 16 patients between 2013 and 2015 with multi-recurrent ventral hernia. All patients were treated preoperatively with both Botulinum Toxin A (BTA) injections to the lateral abdominal wall muscles to confer flaccid paralysis, and short-term PPP to passively expand the abdominal cavity. All patients underwent serial abdominal CT imaging, with pre- and post-treatment circumference measurements of the peritoneal cavity and hernia sac, prior to undergoing operative mesh repair of their hernia., Results: The mean hernia defect size was 236 cm 2 , with mean 28 % loss of domain. The mean overall duration of PPP was 6.2 days. The mean gain in abdominal circumference was 4.9 cm (5.6 %) (p 0.002) after BTA and PPP. Fascial closure and mesh hernia repair were performed in all 16 patients, with no patients suffering from postoperative abdominal hypertension, ventilatory impairment, or wound dehiscence. There are no hernia recurrences to date. Eight patients (50 %) experienced PPP-related complications, consisting of subcutaneous emphysema, pneumothorax, pneumomediastinum, pneumocardium, and metabolic acidosis. No complication required intervention., Conclusions: PPP is a useful adjunct in the repair of complex ventral hernia. It passively expands the abdominal cavity, allowing viscera to re-establish right of domain. At the same time, it helps to minimize the risks of postoperative abdominal compartment syndrome and the sequelae of fascial closure under tension. However, its benefits must be carefully weighed with the risk of serious complications, such as infection, perforation, pneumothorax, and pneumomediastinum.

Purpose: To evaluate and compare the rates and patterns of macular and circumpapillary retinal nerve fiber layer (cRNFL) thickness thinning, assessed by spectral-domain optical coherence tomography (Cirrus SD-OCT), in eyes with preperimetric (PPG) and perimetric glaucoma (PG)., Methods: The present retrospective cohort study included 127 eyes of 75 patients (PPG, 87; PG, 40) with a mean follow-up of 2.53 years. All patients underwent at least 4 SD-OCT examinations. Linear mixed effects models were used to evaluate the rates of changes in relevant cRNFL and macular parameters., Results: Overall, after adjusting for covariates including age, baseline OCT data, and visual field severity, thickness changes in the 6 o'clock (-2.325 μm/y, cRNFL) and inferior outer sector (-2.879 μm/y, macular) showed the highest progression rates among all evaluated parameters. When -0.26 and -0.42 μm/y in average cRNFL and macular thickness changes were used as reference values for age-related physiological loss, 64.4% and 80.5% of PPG eyes and 60% and 70% of PG eyes, respectively, showed higher progression rates than these values. PG eyes showed significantly higher progression rates in the fovea and the inferior inner sector of the macula than did PPG eyes, although no progression rate of any cRNFL parameter differed between the 2 groups., Conclusions: PG and PPG eyes showed different rates and patterns in macular thickness progression when assessed by Cirrus SD-OCT.

Purpose: To evaluate patterns of macular retinal ganglion cell (RGC) loss measured by spectral domain optical coherence tomography in patients with neurologic lesions mimicking glaucoma., Methods: We evaluated four patients with neurological lesions who showed characteristic patterns of RGC loss, as determined by ganglion cell thickness (GCT) mapping., Results: Case 1 was a 30-year-old man who had been treated with glaucoma medication. A left homonymous vertical pattern of RGC loss was observed in his GCT map and a past brain magnetic resonance imaging (MRI) revealed a hemorrhagic lesion around the right optic radiation. Case 2 was a 72-year-old man with a pituitary adenoma who had a binasal vertical pattern of RGC loss that corresponded with bitemporal hemianopsia. Case 3 was a 77-year-old man treated for suspected glaucoma. His GCT map showed a right inferior quadratic pattern of loss, indicating a right superior homonymous quadranopsia in his visual field (VF). His brain MRI revealed a left posterior cerebral artery territory infarct. Case 4 was a 38-year-old woman with an unreliable VF who was referred for suspected glaucoma. Her GCT map revealed a left homonymous vertical pattern of RGC loss, which may have been related to a previous head trauma., Conclusions: Evaluation of the patterns of macular RGC loss may be helpful in the differential diagnosis of RGC-related diseases, including glaucoma and neurologic lesions. When a patient's VF is unavailable, this method may be an effective tool for diagnosing and monitoring transneuronal retrograde degeneration-related structural changes.

Purpose: To evaluate whether pointwise regression analysis of serial measures of retinal sensitivity can predict future visual field (VF) loss., Methods: Medical records of 158 patients with glaucomatous eyes with at least 6 years follow-up and 10 reliable VF exams were retrospectively analyzed. The entire follow-up period was divided into two, roughly corresponding to the first (early period) and second (late period) half of follow-up. Retinal sensitivity data obtained from the Swedish interactive threshold algorithm standard or full-threshold VF tests were analyzed, and linear and first-order exponential regression analyses of retinal sensitivity against time were performed to obtain the slope of regression analysis in each VF test location. Paired t tests were used to compare the slopes of the early and late period in each regression analysis., Results: When assessed by linear regression analysis, inferior nasal location showed highest rate of change (-0.52 dB/year) in early period. Late period showed generally faster rate of progression compared to early period. Superior arcuate and superior and inferior nasal locations showed that early and late slopes did not show significant difference (p value, 0.19 ∼ 0.49). Central and edged locations showed significant difference between the two slopes (p value  < 0.05). First-order exponential regression analysis showed similar result., Discussion: Superior arcuate and superior and inferior nasal areas in VF had a consistent rate of change of retinal sensitivity, indicating that these locations may have the higher capability for prediction of future deterioration. These results suggest that location should be considered when predicting glaucomatous VF progression.

Purpose: To compare the outcomes of Cirrus spectral-domain optical coherence tomography (OCT) and optic disc/retinal nerve fiber layer (RNFL) photographic assessment in detecting glaucomatous progression., Methods: Two-hundred twenty-six eyes of 130 glaucoma patients (mean follow-up: 2.5 years) with at least 5 OCT examinations were included. Eyes were classified into one of four groups (diffuse RNFL defect; localized RNFL defect; no RNFL defect; unidentifiable RNFL status) based on baseline RNFL photographs. After performing the entire series of optic disc/RNFL photographic assessments, the eyes were classified into one of three groups: stable, progressed, and undetermined. Progression was divided into one of four categories (optic disc rim thinning; widening RNFL defect; deepening RNFL defect; new disc hemorrhage). OCT progression was determined using guided progression analysis (GPA) software., Results: One-hundred thirty-nine eyes had diffuse RNFL defects, 34 eyes had localized RNFL defects, 42 eyes had no RNFL defects, and 11 eyes had unidentifiable RNFL at baseline. Forty-six eyes showed at least one category of progression upon expert assessment of optic disc/RNFL photographs, while OCT GPA detected progression in 35 eyes. Among the 34 eyes in which progression was observed in photographs only, 15 showed a new disc hemorrhage, 12 presented deepening of an RNFL defect, 10 showed optic disc rim change, and 6 had widening of an RNFL defect. Among the 23 eyes processed only by OCT GPA, 18 had a diffuse RNFL defect at baseline., Conclusion: OCT GPA was more sensitive in eyes with a diffuse RNFL defect whereas photographic assessment was better for detecting optic disc hemorrhage and deepening of an RNFL defect when evaluating structural progression.

Purpose: To quantify long-term changes in anterior segment (AS) parameters after laser peripheral iridotomy (LPI) using AS optical coherence tomography (OCT) in primary angle-closure suspect (PACS)., Methods: Thirty-two PACS subjects were imaged at pre-LPI and 2 weeks and 18 months post-LPI using AS OCT. Anterior chamber depth (ACD), iris curvature (IC), iris thickness at 750 and 1500 μm from the scleral spur (IT750, 1500), lens vault (LV), anterior chamber area (AA), and iris area (IA) were estimated by ImageJ software (version 1.46). Anterior chamber angle (ACA) parameters (angle opening distance [AOD750], angle recess area [ARA750], and trabecular iris space area [TISA750]) were provided by the manufacturer. Parameters were compared before and after LPI. Uni- and multivariate regression analysis was performed to evaluate factors associated with ACA narrowing., Results: Mean AA (14.63 vs. 15.87 mm(2)) and three ACA parameters (AOD750 [0.17 vs. 0.28 mm], TISA750 [0.07 vs. 0.11 mm(2)], and ARA750 [0.08 vs. 0.13 mm(2)]) increased at 2 weeks post-LPI (all P < 0.001). The IT750, 1500 and IC also showed change at 2 weeks post-LPI. Eighteen months post-LPI, IC (0.34 vs. 0.16 mm, P < 0.001) and LV (0.88 vs. 1.01 mm, P = 0.001) were significantly different, while three ACA parameters were not different from their pre-LPI status. At post-LPI 18 months, LV was significantly associated with ACA narrowing (P = 0.026)., Conclusions: The ACA tended to be narrowed at 18 months post-LPI despite resolution of pupillary block, which may be due to LV increment. Our results warrant continuous follow-up of narrow-angle patients after LPI.

Purpose: To investigate the possibility of classifying angle closure eyes in terms of features provided by anterior segment optical coherence tomography (AS OCT)., Methods: Angle closure (primary angle closure [PAC] or PAC glaucoma [PACG]) eyes diagnosed by gonioscopy were imaged using AS OCT under the same lighting conditions. Anterior chamber depth (ACD), anterior chamber width (ACW), iris cross-sectional area (IA), iris thickness at 750 μm from the scleral spur (IT750), iris curvature (IC), lens vault (LV), and anterior chamber area (ACA) were determined using Image J software (ver. 1.44). A hierarchical cluster analysis using Ward's method was performed using AS parameters obtained by AS OCT and axial length (AXL)., Results: A hierarchical cluster analysis was performed on 166 angle closure eyes and produced two clusters. The first cluster (84 eyes) was characterized by higher ACD (2.24 mm), higher ACA (12.5 mm(2)), higher IT750 (0.44 mm), higher ACW (11.2 mm), lower LV (0.85 mm), and higher AXL (23.5 mm) compared with the second cluster (82 eyes, 1.82 mm, 9.5 mm(2), 0.38 mm, 10.8 mm, 1.1 mm, and 22.8 mm, respectively). The second cluster had essentially higher LV and lower ACA than the first cluster. Most parameters were significantly different between two clusters except IC (P = 0.76)., Conclusions: Our hierarchical cluster analysis indicated two clusters with quite different features existed in our total angle closure population. Our results suggest the possibility of subclassifying angle closure eyes according to AS OCT parameters.

Phosphoinositide 3-kinase α (PI3Kα) is a lipid kinase that plays a key regulatory role in several cellular processes. The mutation or amplification of this kinase in humans has been implicated in the growth of multiple tumor types. Consequently, PI3Kα has become a target of intense research for drug discovery. Our studies began with the identification of benzothiazole compound 1 from a high throughput screen. Extensive SAR studies led to the discovery of sulfonamide 45 as an early lead, based on its in vitro cellular potency. Subsequent modifications of the central pyrimidine ring dramatically improved enzyme and cellular potency and led to the identification of chloropyridine 70. Further arylsulfonamide SAR studies optimized in vitro clearance and led to the identification of 82 as a potent dual inhibitor of PI3K and mTOR. This molecule exhibited potent enzyme and cell activity, low clearance, and high oral bioavailability. In addition, compound 82 demonstrated tumor growth inhibition in U-87 MG, A549, and HCT116 tumor xenograft models.

c-Met is a receptor tyrosine kinase that plays a key role in several cellular processes but has also been found to be overexpressed and mutated in different human cancers. Consequently, targeting this enzyme has become an area of intense research in drug discovery. Our studies began with the design and synthesis of novel pyrimidone 7, which was found to be a potent c-Met inhibitor. Subsequent SAR studies identified 22 as a more potent analog, whereas an X-ray crystal structure of 7 bound to c-Met revealed an unexpected binding conformation. This latter finding led to the development of a new series that featured compounds that were more potent both in vitro and in vivo than 22 and also exhibited different binding conformations to c-Met. Novel c-Met inhibitors have been designed, developed, and found to be potent in vitro and in vivo.

S100 proteins are a family of 10-14 kDa EF-hand-containing calcium binding proteins that function to transmit calcium-dependent cell regulatory signals. S100 proteins have no intrinsic enzyme activity but bind in a calcium-dependent manner to target proteins to modulate target protein function. Transglutaminases are enzymes that catalyze the formation of covalent epsilon-(gamma-glutamyl)lysine bonds between protein-bound glutamine and lysine residues. In the present study we show that transglutaminase-dependent covalent modification is a property shared by several S100 proteins and that both type I and type II transglutaminases can modify S100 proteins. We further show that the reactive regions are at the solvent-exposed amino- and carboxyl-terminal ends of the protein, regions that specify S100 protein function. We suggest that transglutaminase-dependent modification is a general mechanism designed to regulate S100 protein function.

Purpose: A well-recognized characteristic of venous ulcers is impaired healing. Fibroblasts cultured from venous ulcers (wound-fb) have been shown to have reduced growth rates and are larger than normal fibroblasts (normal-fb) from the ipsilateral limb. Reduced growth capacity and morphologic changes are 2 well-known traits of cellular senescence. Other molecular changes are overexpression of matrix proteins, such as cellular fibronectin (cFN), and enhanced activity of beta-galactosidase at pH of 6.0 (senescence associated beta-Gal, or SA-beta-Gal). Senescence, an irreversible arrest of cell proliferation with maintenance of metabolic functions, may represent in vivo aging and thus may be related to impaired healing., Methods: Cultured normal-fb and wound-fb from 7 venous ulcer patients (average age, 51 years) were obtained by taking punch biopsies of the perimeter of the ulcer and from the ipsilateral thigh of the same patient. Growth rates, SA-beta-Gal activity, and level of cFN protein (immunoblot) and message (Northern blot) were measured., Results: In all patients, wound-fb growth rates were significantly lower than those of normal-fb (P =.006). A higher percentage of SA-beta-Gal positive cells were found in all wound-fb (average, 6.3% vs. 0.21%; P =.016). The level of cFN, was consistently higher in all wound-fb tested. Also, in 4 patients, the level of cFN messenger RNA (mRNA) was increased., Conclusion: Fibroblasts cultured from venous ulcers exhibited characteristics associated with senescent cells. Accumulation of senescent cell in ulcer environment may be associated with impaired healing.

We report the characterization of a new sodium channel blocker, mu-conotoxin PIIIA(mu-PIIIA). The peptide has been synthesized chemically and its disulfide bridging pattern determined. The structure of the new peptide is: [sequence: see text] where Z = pyroglutamate and O = 4-trans-hydroxyproline. We demonstrate that Arginine-14 (Arg14) is a key residue; substitution by alanine significantly decreases affinity and results in a toxin unable to block channel conductance completely. Thus, like all toxins that block at Site I, mu-PIIIA has a critical guanidinium group. This peptide is of exceptional interest because, unlike the previously characterized mu-conotoxin GIIIA (mu-GIIIA), it irreversibly blocks amphibian muscle Na channels, providing a useful tool for synaptic electrophysiology. Furthermore, the discovery of mu-PIIIA permits the resolution of tetrodotoxin-sensitive sodium channels into three categories: (1) sensitive to mu-PIIIA and mu-conotoxin GIIIA, (2) sensitive to mu-PIIIA but not to mu-GIIIA, and (3) resistant to mu-PIIIA and mu-GIIIA (examples in each category are skeletal muscle, rat brain Type II, and many mammalian CNS subtypes, respectively). Thus, mu-conotoxin PIIIA provides a key for further discriminating pharmacologically among different sodium channel subtypes.

The three-dimensional structure of conotoxin psi-PIIIE, a 24-amino acid peptide from Conus purpurascens, has been solved using two-dimensional (2D) 1H NMR spectroscopy. Conotoxin psi-PIIIE contains the same disulfide bonding pattern as the mu-conotoxins, which target skeletal muscle sodium channels, but has been shown to antagonize the acetylcholine gated cation channel through a noncompetitive mechanism. Structural information was obtained by the analysis of a series of 2D NOESY spectra as well as measurement of coupling constants from 1D 1H and PE-COSY NMR experiments. Molecular modeling calculations included the use of the distance geometry (DG) algorithm, simulated annealing techniques, and the restrained molecular dynamics method. The resulting structures are considerably similar to the previously published structures for the mu-conotoxins GIIIA and GIIIB, despite the lack of sequence conservation between conotoxin psi-PIIIE and the mu-conotoxins. The structure consists of a series of tight turns, each turn occurring in the position analogous to those of turns described in mu-GIIIA and mu-GIIIB. This suggests the disulfide bonding pattern is able to largely direct the structure of the peptides, creating a stable structural motif which allows extensive sequence substitution of non-cystine residues.

alpha-Conotoxin MII, isolated from Conus magus, is a potent peptidic toxin which specifically targets the mammalian neuronal nicotinic acetylcholine receptor, alpha3beta2 subtype. The three-dimensional structure of alpha-conotoxin MII in aqueous solution has been determined by two-dimensional 1H NMR spectroscopy. NOE-derived distances, refined by an iterative relaxation matrix approach, as well as dihedral and chirality restraints were used in high-temperature biphasic simulated annealing calculations. Fourteen minimum energy structures out of 50 subjected to the SA simulations were chosen for evaluation; these 14 structures have a final RMS deviation of 0.76 +/- 0.31 and 1.35 +/- 0.34 A for the backbone and heavy atoms, respectively. The overall structure is unusually well-defined due to a large helical component around the two disulfide bridges. The principal backbone folding motif may be common to a subclass of alpha-conotoxins. There are two distinct surfaces on the molecule almost at right angles to one another. One entirely consists of the hydrophobic residues Gly1, Cys2, Cys3, Leu15, and Cys16. The second comprises the hydrophilic residues Glu11, His12, Ser13, and Asn14. These surfaces on the ligand could be essential for the subtype-specific recognition of the receptor.

A paralytic peptide, psi-conotoxin Piiie has been purified and characterized from Conus purpurascens venom. Electrophysiological studies indicate that the peptide inhibits the nicotinic acetylcholine receptor (nAChR). However, the peptide does not block the binding of alpha-bungarotoxin, a competitive nAChR antagonist. Thus, psi-conotoxin Piiie appears to inhibit the receptor at a site other than the acetylcholine-binding site. As ascertained by sequence analysis, mass spectrometry, and chemical synthesis, the peptide has the following covalent structure: HOOCCLYGKCRRYOGCSSASCCQR* (O = 4-trans hydroxyproline; * indicates an amidated C-terminus). The disulfide connectivity of the toxin is unrelated to the alpha- or the alphaA-conotoxins, the Conus peptide families that are competitive inhibitors of the nAChR, but shows homology to the mu-conotoxins (which are Na+ channel blockers).

A high-resolution solution conformation of a novel conotoxin, [Pro 7,13] alpha A-conotoxin PIVA, GCCGSYPNAACHPCSCKDROSYCGQ-NH2, has been determined by two-dimensional 1H NMR methods and distance geometry calculations. The total of 324 NOE-derived interproton distance restraints including 33 long-range NOE restraints as well as 11 phi and 7 chi 1 torsion angle restraints was used for computation of structures. Back-calculation from the experimental NOE spectrum has provided 49 new NOE restraints and yielded the final R-factors of Ra = 0.641 and Rb = 0.157. The final RMSD values are 0.90 and 1.16 A for the backbone and the heavy atoms, respectively. The C-terminal half of the molecule involving the residues 12-24 is extremely well-defined with a backbone RMSD value of 0.56 A, whereas the N-terminal 3-11 disulfide loop is relatively flexible, possessing a backbone RMSD value of 1.09 A. The [Pro 7,13] alpha A-conotoxin PIVA does not contain any significant secondary structure although the 21S-24G nearly completes one turn of a 3(10) helix. The overall protein fold is largely maintained by the three disulfide bridges of 2-16, 3-11, and 14-23. The presence of the three disulfide bridges imposes geometric constraints that force the molecule to form six continuous bends involving the following residues: 3C-5S, 7P-10A, 12H-14C, 15S-17K, 17K-19R, and 21S-25Q. The overall shape of the [Pro 7,13] alpha A-conotoxin PIVA can be described as an "iron". Residues 15S-19R form a loop that protrudes out of the "bottom plate" formed by the rest of the protein and constitute the handle of the iron. The N-terminal tip of the molecule is relatively immobile due to attractive electrostatic interactions between the gamma-hydroxyl group of 20 Hyp and the phenolic hydroxyl group of 22Y. The flexible 3-11 disulfide loop consists mostly of hydrophobic residues, while the best-defined 14-23 disulfide loop contains the highly charged hydrophilic 15S-19R "handle" domain exposed to the exterior of the protein. Binding to nicotinic acetylcholine receptor can be mediated through two different types of interactions: one involving the aromatic hydrophobic residues such as 6Y and 12H and the other involving the positively charged hydrophilic side chain of the 19R. The side chain of the 19R in the [Pro 7, 13] alpha A-conotoxin PIVA and that of the 9R of the alpha-conotoxin G1, and also the side chains of the 12H and 6Y in the former and those of 10H and 11Y in the latter can be aligned to point to the same direction when the corresponding backbone atoms are superimposed to an RMSD value of 2.5 A.

Whole-body positron emission tomography (PET) has recently emerged as an important imaging tool for cancer detection and staging. Initial applications of the technique have been primarily qualitative. One of the major reasons is the limits imposed by kinetically undersampled data over the whole body, as opposed to the standard method of continuous dynamic sampling in one body location. In this paper, a new estimation method using weighted nonlinear least squares (WNLS) for the first bed position and Bayesian regression (BR) for subsequent positions is proposed. A general criterion for designing optimal sampling schedules which maximizes the measurement information with multiple bed positions is developed. The overall approach is illustrated with the problem of estimating the metabolic rate of glucose (MRGLu) in tumors at different axial positions (image bed positions) in the body by using computer simulations and patient data. The results show that estimates of MRGLu using sparse data and the optimized Bayesian approach are comparable with those obtained by standard methods and fully sampled data. This study demonstrates the potential of the technique described for quantification where several bed positions have to be used to image all the regions of interest (ROI).

Some venomous animals capture prey with remarkable efficiency and speed. The purple cone, Conus purpurascens, uses two parallel physiological mechanisms requiring multiple neurotoxins to immobilize fish rapidly: neuromuscular block, and excitotoxic shock. The latter requires the newly characterized peptide kappa-conotoxin PVIIA, which inhibits the Shaker potassium channel 2-4, and beta-conotoxin PVIA5, which delays sodium-channel inactivation. Despite the extreme biochemical diversity in venoms, the number of effective strategic alternatives for prey capture are limited. How securely prey is initially tethered may strongly influence the venom strategy evolved by a predator.

The major groups of Conus peptides previously characterized from fish-hunting cone snail venoms (the alpha-, mu-, and omega-conotoxins) all blocked neuromuscular transmission. A novel activity, the "lockjaw peptide", from the fish-hunting Conus purpurascens, caused a rigid (instead of flaccid) paralysis in fish and increased excitability at the neuromuscular junction (instead of a block). We report the purification, biological activity, biochemical and preliminary physiological characterization, and chemical synthesis of the lockjaw peptide and the sequence of a cDNA clone encoding its precursor. Taken together, the data lead us to conclude that the lockjaw peptide is a vertebrate-specific delta-conotoxin, which targets voltage-sensitive sodium channels. The sequence of the peptide, which we designate delta-conotoxin PVIA, is (O = 4-trans-hydroxyproline) EACYAOGTFCGIKOGLCCSEFCLPGVCFG-NH2. This is the first of a diverse spectrum of Conus peptides which are excitotoxins in vertebrate systems.

A novel peptide toxin, delta-conotoxin GmVIA, was purified from the venom of Conus gloriamaris, a mollusc-hunting snail. It consists of 29 amino acids, including six Cys residues: [sequence: see text] The pattern of disulfide connectivity (4-19, 12-24, and 18-29) is the same as for the omega-conotoxins, which are Ca2+ channel ligands. However, the peptide does not compete with omega-conotoxin for binding to membrane preparations from frog, rat, and chick brain. Instead, initial electrophysiological results suggest that the peptide induces action potential broadening in molluscan neurons by slowing down Na+ current inactivation. Synthetic delta-conotoxin GmVIA was prepared by solid-phase methods and appeared identical in all respects to the natural material. The chromatographic behavior of native and reduced delta-conotoxins is quite remarkable, suggesting that the disulfides form a core which forces hydrophobic residues to point out toward the solvent.