Carcinogenicity of dextran sulfate sodium in relation to its molecular weight

The carcinogenicity of dextran and 3 kinds of dextran sulfate sodium with different molecular weights and almost the same sulfur content were compared in ACI rats. Dextran sulfate sodium of molecular weight 54,000 showed a strong carcinogenic activity when it was given orally as 2.5% diet, whereas dextran sulfate sodium of molecular weight 520,000 and 9500 and dextran showed no significant carcinogenicity, i.e. the peak of carcinogenic activity of dextran sulfate sodium appeared at molecular weight 54,000, and dextran sulfates with larger or smaller molecular weights had no carcinogenic activity.     

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.     

Tc-99m HMPAO SPECT imaging of the central nervous system in tuberous sclerosis

Tc-99m HMPAO was used to evaluate cerebral perfusion in a patient with tuberous sclerosis. The SPECT images demonstrated reduced HMPAO uptake in regions corresponding with MRI-confirmed locations of cortical tubers. These results indicate that the lesions are characterized by vascular perfusion deficits and support the hypothesis that cortical tubers result from developmental abnormalities of the embryonic central nervous system.     

Epilation of hair-bearing urethral grafts using the neodymium:YAG surgical laser

Nonhair-bearing skin should be used when grafting is necessary during urethroplasty for stricture or hypospadias repair. Occasionally, this is not possible or hair-bearing skin is used inadvertently. Traditionally, electrocoagulation has been the method used for epilation when intraluminal hair has become a problem, such as interfering with flow, as a focus for recurrent urinary tract infection or acting as a nidus for calculus formation. Electrocautery also is performed during grafting in an attempt to prevent the growth of hair when hair-bearing skin is used. Unfortunately, due to lack of penetration the hair follicles are not destroyed and the epilating procedure fails or is only partially successful. The neodymium:YAG surgical laser can photocoagulate tissue to a depth up to 5.0 mm, and thus, has the ability to destroy hair follicles. We report 4 cases presenting with clinical problems directly related to hair-bearing urethral grafts successfully treated by neodymium:YAG laser epilation.