Different amino acid substitutions at the same position in rhodopsin lead to distinct phenotypes

PURPOSE: Identification of a novel rhodopsin mutation in a family with retinitis pigmentosa and comparison of the clinical phenotype to a known mutation at the same amino acid position. METHODS: Screening for mutations in rhodopsin was performed in 78 patients with retinitis pigmentosa. All exons and flanking intronic regions were amplified by PCR, sequenced, and compared to the reference sequence derived from the National Center for Biotechnology Information (NCBI, Bethesda, MD) database. Patients were characterized clinically according to the results of best corrected visual acuity testing (BCVA), slit lamp examination (SLE), funduscopy, Goldmann perimetry (GP), dark adaptometry (DA), and electroretinography (ERG). Structural analyses of the rhodopsin protein were performed with the Swiss-Pdb Viewer program available on-line (http://www.expasy.org.spdvbv/ provided in the public domain by Swiss Institute of Bioinformatics, Geneva, Switzerland). RESULTS: A novel rhodopsin mutation (Gly90Val) was identified in a Swiss family of three generations. The pedigree indicated autosomal dominant inheritance. No additional mutation was found in this family in other autosomal dominant genes. The BCVA of affected family members ranged from 20/25 to 20/20. Fundus examination showed fine pigment mottling in patients of the third generation and well-defined bone spicules in patients of the second generation. GP showed concentric constriction. DA demonstrated monophasic cone adaptation only. ERG revealed severely reduced rod and cone signals. The clinical picture is compatible with retinitis pigmentosa. A previously reported amino acid substitution at the same position in rhodopsin leads to a phenotype resembling night blindness in mutation carriers, whereas patients reported in the current study showed the classic retinitis pigmentosa phenotype. The effect of different amino acid substitutions on the three-dimensional structure of rhodopsin was analyzed by homology modeling. Distinct distortions of position 90 (shifts in amino acids 112 and 113) and additional hydrogen bonds were found. CONCLUSIONS: Different amino acid substitutions at position 90 of rhodopsin can lead to night blindness or retinitis pigmentosa. The data suggest that the property of the substituted amino acid distinguishes between the phenotypes.

Microbiological tined-lead examination: does prolonged sacral neuromodulation testing induce infection?

OBJECTIVE: To investigate whether prolonged sacral neuromodulation (SNM) testing induces a substantial risk of infection because of the percutaneous passage of the extension wire. PATIENTS AND METHODS: A consecutive series of 20 patients with negative prolonged SNM testing for >or=14 days who underwent tined-lead explantation were prospectively evaluated. The explanted tined leads were sent for microbiological examination. The tined lead, gluteal, and extension wire incision sites were investigated for clinical signs of infection according to the Centers for Disease Control and Prevention classification system. RESULTS: In all, 17 patients had bilateral and three unilateral implanted tined leads. The median (range) test period was 30 (21-62 days). Bacterial growth (Staphylococcus species) was detected in four of 20 (20%) patients on seven of 37 (19%) explanted tined leads. There were clinical signs of infection in one of 20 (5%) patients at none of 37 tined lead, one of 20 (5%) gluteal, and none of 20 extension wire incision sites. There were no clinical signs of infection in the remaining three of four patients with bacterial growth. CONCLUSIONS: After prolonged tined-lead testing, we found an infection rate comparable to that reported with the usual short test period. In addition, most patients with bacterial growth on tined leads showed no clinical signs of infection. Thus, prolonged tined-lead testing does not seem to induce clinically relevant infection, warranting randomized trials.

Safety of prolonged sacral neuromodulation tined lead testing

OBJECTIVE: Prolonged sacral neuromodulation (SNM) testing is more reliable for accurate patient selection than the usual test period of 4-7 days. However, prolonged testing was suspected to result in a higher complication rate due to infection via the percutaneous passage of the extension wire. Therefore, we prospectively assessed the complications associated with prolonged tined lead testing. PATIENTS AND METHODS: A consecutive series of 44 patients who underwent prolonged tined lead testing for at least 14 days between May 2002 and April 2007 were evaluated. Complications during prolonged tined lead testing, during and after tined lead explantation and during follow-up after implantation of the implantable pulse generator (IPG) were registered prospectively. RESULTS: Four patients suffered from urgency-frequency syndrome, 13 from urge incontinence, 18 from non-obstructive chronic urinary retention and nine from chronic pelvic pain syndrome. The median test phase was 30 days (interquartile range [IQR] 21-36). Thirty-two of the 44 patients (73%) had successful prolonged tined lead testing and 31 of these (97%) underwent the implantation of the IPG. The median follow-up of the IPG implanted patients was 31 months (IQR 20-41). The complication rate was 5% (2/44) during prolonged tined lead testing and 16% (5/31) during follow-up of the IPG implanted patients, respectively. None of the complications could be attributed to prolonged testing. No infections were observed during the study period. CONCLUSIONS: This prospective, observational non-randomised study suggests prolonged SNM tined lead testing is a safe procedure. Based on the low complication rate and the increased reliability for accurate patient selection, this method is proposed as a possible standard test procedure, subject to confirmation by further randomised, controlled clinical studies.

PERFORMANCE EVALUATION OF LLDPE/CaCO3 MODIFIERS WITH AND WITHOUT TITANATE COUPLING AGENT ON ASPHALT BINDER AND MIXTURE

The complexity and challenge created by asphalt material motivates researchers and engineers to investigate the behavior of this material to develop a better understanding, and improve the performance of asphalt pavement. Over decades, a wide range of modification at macro, meso, micro and nano scales have been conducted to improve the performance of asphalt pavement. This study was initiated to utilize the newly developed asphalt modifier pellets. These pellets consisted of different combinations of calcium carbonate (CaCO3), linear low-density polyethylene (LLDPE) and titanate coupling agent (CA) to improve the asphalt binder as well as pavement performance across a wide range of temperature and loading pace. These materials were used due to their unique characteristics and promising findings from various industries, especially as modifiers in pavement material. The challenge is to make sure the CaCO3 disperses very well in the mixture. The rheological properties of neat asphalt binder PG58-28 and modified asphalt binder (PG58-28/LLDPE, PG58-28/CaCO3, PG58-28/CaCO3/LLDPE, and PG58-28/CaCO3/LLDPE/CA), were determined using rotational viscometer (RV) test, dynamic shear rheometer (DSR) test and bending beam rheometer test. In the DSR test, the specimens were evaluated using frequency sweep and multiple shear creep recovery (MSCR). The asphalt mixtures (aggregate/PG58-28, aggregate/ PG58-28/LLDPE, aggregate/PG58-28/CaCO3, aggregate/PG58-28/LLDPE/CaCO3 and aggregate/PG58-28/LLDPE/CaCO3/CA) were evaluated using the four point beam fatigue test, the dynamic modulus (E*) test, and tensile strength test (to determines tensile strength ratio, TSR). The RV test results show that all modified asphalt binders have a higher viscosity compared to the neat asphalt binder (PG58-28). Based on the Jnr results (using MSCR test), all the modified asphalt binders have a better resistance to rutting compared to the neat asphalt binder. A higher modifier contents have resulted in a better recovery percentage of asphalt binder (higher resistance to rutting), except the specimens prepared using PECC’s modified asphalt binder (PG58-28/CaCO3/LLDPE). The BBR test results show that all the modified asphalt binders have shown comparable performance in term of resistance to low temperature cracking, except the specimen prepared using the LLDPE modifier. Overall, 5 wt% LLDPE modified asphalt binder was found to be the best asphalt binder in terms of resistance to rutting. Meanwhile, 3 wt% PECC-1CA’s modified asphalt binder can be considered as the best (in terms of resistance to thermal cracking) with the lowest mean critical cracking temperature. The appearance of CaCO3 was found useful merely in improving the resistance to fatigue cracking of asphalt mixture. However, application of LLDPE has undermined the fatigue life of asphalt mixtures. Adding LLDPE and coupling agent throughout this study does not sufficiently help in terms of elastic behavior which essential to enhance the resistance to fatigue cracking. In contrast, application of LLDPE has increased the indirect tensile strength values and TSR of asphalt mixtures, indicates a better resistance to moisture damage. The usage of the coupling agent does not change the behavior of the asphalt mixture, which could be due to imbalance effects resulted by combination of LLDPE and CaCO3 in asphalt binder. Further investigations without incorporating CaCO3 should be conducted further. To investigate the feasibility of using LLDPE and coupling agent as modifiers in asphalt pavements, more research should be conducted on different percentages of LLDPE (less than 3 wt%), and at the higher and w wider range of coupling agent content, from 3 wt% to 7 wt% based on the polymer mass.

Epothilones as lead structures for the synthesis-based discovery of new chemotypes for microtubule stabilization

Epothilones are macrocyclic bacterial natural products with potent microtubule-stabilizing and antiproliferative activity. They have served as successful lead structures for the development of several clinical candidates for anticancer therapy. However, the structural diversity of this group of clinical compounds is rather limited, as their structures show little divergence from the original natural product leads. Our own research has explored the question of whether epothilones can serve as a basis for the development of new structural scaffolds, or chemotypes, for microtubule stabilization that might serve as a basis for the discovery of new generations of anticancer drugs. We have elaborated a series of epothilone-derived macrolactones whose overall structural features significantly deviate from those of the natural epothilone scaffold and thus define new structural families of microtubule-stabilizing agents. Key elements of our hypermodification strategy are the change of the natural epoxide geometry from cis to trans, the incorporation of a conformationally constrained side chain, the removal of the C3-hydroxyl group, and the replacement of C12 with nitrogen. So far, this approach has yielded analogs 30 and 40 that are the most advanced, the most rigorously modified, structures, both of which are potent antiproliferative agents with low nanomolar activity against several human cancer cell lines in vitro. The synthesis was achieved through a macrolactone-based strategy or a high-yielding RCM reaction. The 12-aza-epothilone ("azathilone" 40) may be considered a "non-natural" natural product that still retains most of the overall structural characteristics of a true natural product but is structurally unique, because it lies outside of the general scope of Nature's biosynthetic machinery for polyketide synthesis. Like natural epothilones, both 30 and 40 promote tubulin polymerization in vitro and at the cellular level induce cell cycle arrest in mitosis. These facts indicate that cancer cell growth inhibition by these compounds is based on the same mechanistic underpinnings as those for natural epothilones. Interestingly, the 9,10-dehydro analog of 40 is significantly less active than the saturated parent compound, which is contrary to observations for natural epothilones B or D. This may point to differences in the bioactive conformations of N-acyl-12-aza-epothilones like 40 and natural epothilones. In light of their distinct structural features, combined with an epothilone-like (and taxol-like) in vitro biological profile, 30 and 40 can be considered as representative examples of new chemotypes for microtubule stabilization. As such, they may offer the same potential for pharmacological differentiation from the original epothilone leads as various newly discovered microtubule-stabilizing natural products with macrolactone structures, such as laulimalide, peloruside, or dictyostatin.

Alloys of Lead and Tellurium

Prior to the last few years little practical use was made of the element tellurium, which is obtained from gold and silver tellurides and from the slimes of electro­lytic copper refineries. Lately, however, more study has been made of its properties when alloyed with other metals. It was the purpose of this thesis to study the effects of the addition of tellurium to lead, particularly in small amounts.

The Effects of Zinc Sulphate, Manganese Sulphate, and Iron Sulphate on the Lead Storage Cell.

The lead storage battery as it is used today is made up of the pasted type plates of lead dioxide, the anode, and sponge lead, the cathode, and wooden or hard rubber separators, which serve to insulate these from one another. In manufacturing these, it is desirable to keep them free from impurities.

A Rapid Determination of Small Amounts of Lead in Zinc

This investigation, carried on in the metallur­gical laboratories at the Montana School of Mines, was undertaken with the desire to work out a rapid method for the estimation, or the determination, of the amount of lead in zinc.

Electrolysis of Molten Mixtures of Galena and Lead Chloride.

Electrolysis of molten mixtures of lead chloride and galena was carried out under various conditions of temperature, time, composition, and current densities; without a diaphram, and with various diaphrams. Continuous runs, with necessary additions of lead sulfide and lead chloride to maintain a melt of the proper composition, were attempted on a small scale.