Progress toward re‐engineering non‐ribosomal peptide synthetase proteins: a potential new source of pharmacological agents

Many important pharmaceutical agents, including vancomycin, bleomycin, cyclosporin, and several antibiotics, are produced by non‐ribosomal peptide synthetase (NRPS) enzymes in microorganisms. The NRPS pathway produces an extensive library of products using multienzyme complexes acting in an assembly‐line fashion. Engineering an NRPS system to produce an even greater variety of products, some of which may also have beneficial therapeutic value, would be an enormous advantage. Several approaches have been successful in generating novel NRPS products: mutational biosynthesis during which nonnatural substrates are fed to an organism; domain and module swapping between different species to generate hybrid enzymes; and rational site‐directed mutagenesis, based either on phylogeny or computational prediction, intended to switch substrate specificity and produce altered products. This review will highlight the progress in these areas and describe research in the future that will extend the capacity for re‐engineering NRPS systems. Drug Dev. Res. 66:9–18, 2006. © 2006 Wiley‐Liss, Inc.     

The effect of optical design on micromanipulator spot size using CO2 laser irradiation

Objective: The study goal was to compare the laser spot size created using reflective and refractive micromanipulators with a CO₂ laser and to determine the sensitivity of spot size to laser power. Study Design and Setting: A CO₂ laser and operating microscope (400-mm focal length) was coupled to either a reflective (Cassegrain-like) or refractive micromanipulator. Laser spot size was determined by measuring the region of ablation created by laser irradiation of wood (dry tongue depressors), exposed photographic film, and agar gel using optical micrometry. Laser power varied from 0.5 to 20 W with pulse durations of 0.1 and 0.5 second. Results: The reflective micromanipulator demonstrated overall smaller spot sizes for a given laser power and lower incremental change in spot size with increasing power. The reflective design demonstrated less sensitivity to increases in laser power. Conclusions: Micromanipulator optical design can result in significant differences in laser spot size. The reflective device used in this study demonstrated less sensitivity to increasing laser power. (Otolaryngol Head Neck Surg 2002;126:593-597.)     

The contemporary role of antioxidant therapy in attenuating liver ischemia-reperfusion injury: a review.

Oxidative stress is an important factor in many pathological conditions such as inflammation, cancer, ageing and organ response to ischemia-reperfusion. Humans have developed a complex antioxidant system to eliminate or attenuate oxidative stress. Liver ischemia-reperfusion injury occurs in a number of clinical settings, including liver surgery, transplantation, and hemorrhagic shock with subsequent fluid resuscitation, leading to significant morbidity and mortality. It is characterized by significant oxidative stress but accompanied with depletion of endogenous antioxidants. This review has 2 aims: firstly, to highlight the clinical significance of liver ischemia-reperfusion injury, the underlying mechanisms and the main pathways by which the antioxidants function, and secondly, to describe the new developments that are ongoing in antioxidant therapy and to present the experimental and clinical evidence about the role of antioxidants in modulating hepatic ischemia-reperfusion injury.     

A new transthyretin variant (Glu61Gly) associated with cardiomyopathy.

We report the identification of a new transthyretin (TTR) gene mutation and variant protein, Glu61Gly, in a 55-year-old man with progressive cardiomyopathy, mild peripheral neuropathy and bilateral carpal tunnel syndrome. A diagnosis of TTR-associated familial amyloidosis (ATTR) was considered after an endomyocardial biopsy revealed amyloid deposits in the heart of a patient who had no family history of amyloidosis and no evidence of a plasma cell dyscrasia. Serum screening for a TTR variant by isoelectric focusing (IEF) was positive and prompted further studies to identify the genetic abnormality and to characterize the amyloidogenic protein. Direct DNA sequence analysis of all four coding regions in the TTR gene demonstrated heterozygosity in exon 3. Near equal amounts of guanine (G) and adenine (A) were observed at the second base position of codon 61. The wild-type (GAG) and mutated (GGG) sequences found in codon 61 correspond to glutamic acid (Glu) and glycine (Gly) residues, amino acids which differ in mass by -72 Da. Mass spectrometric analyses of TTR immunoprecipitated from serum showed the presence of both wild-type and variant proteins. The observed mass results for the wild-type and variant proteins were consistent with the predicted values calculated from the genetic analysis data.     

Perceptions and attitudes of Canadian orthodontists regarding digital and electronic technology.

INTRODUCTION: To plan for future acceptance and implementation of computer-related technology, it is necessary to understand orthodontists' current perceptions and attitudes toward emerging technologies. METHODS: An anonymous, self-administered, mail-out survey of Canadian orthodontists was conducted. The response rate was 45.6% (304/667). RESULTS: Most orthodontists indicated that computer technology could improve current practice efficiency and quality of patient care. Only 15% reported that digital models are quite or very useful; 73.6%, 69.1%, 55%, and 37.4% agreed or strongly agreed with using digital and electronic technology to consult with other dental specialists, other orthodontists, general dentists, and the public, respectively. Cost of the technology was reported as a significant or insurmountable obstacle by 54% of the respondents. Interprovincial legislation, unclear consultation remuneration guidelines, and lack of comfort with the technology were not perceived as significant obstacles. Only 36% reported security or privacy issues as a significant or insurmountable obstacle. CONCLUSIONS: Canadian orthodontists seem to view digital and electronic technology as useful and capable of improving their offices' efficiency and production. Although they are sensitive to some potential obstacles, they are willing to overcome these and incorporate the technology into their practices.     

Noninvasive tests for arterial structure, function, and compliance: do they identify risk or diagnose disease?

BACKGROUND: Brachial artery reactivity (BAR), carotid intima-media thickness (IMT), and applanation tonometry for evaluation of total arterial compliance may provide information about preclinical vascular disease. We sought to determine whether these tests could be used to identify patients with coronary artery disease (CAD) without being influenced by their ability to identify those at risk for CAD developing. METHODS: We studied 100 patients and compared 3 groups: 35 patients with known CAD; 34 patients with symptoms and risk factors but no CAD identified by stress echocardiography (risk group); and 31 control subjects. BAR and IMT were measured using standard methods, and total arterial compliance was calculated by the pulse-pressure method from simultaneous radial applanation tonometry and pulsed wave Doppler of the left ventricular outflow. Ischemia was identified as a new or worsening wall-motion abnormality induced by stress. RESULTS: In a comparison between the control subjects and patients either at risk for developing CAD or with CAD, the predictors of risk for CAD were: age (P =.01); smoking history (P =.002); hypercholesterolemia (P =.002); and hypertension (P =.004) (model R = 0.82; P =.0001). The independent predictors of CAD were: IMT (P =.001); BAR (P =.04); sex (P =.005); and hypertension (P =.005) (model R = 0.80; P =.0001). CONCLUSION: IMT, BAR, and traditional cardiovascular risk factors appear to identify patients at risk for CAD developing. However, only IMT was significantly different between patients at risk for developing CAD and those with overt CAD.