Preservation of global cardiac function in the rabbit following protracted ischemia/reperfusion using monophosphoryl lipid A (MLA)

Monophosphoryl lipid A (MLA), a derivative of the minimal substructure of lipopolysaccharide (lipid A) possesses immunomodulatory activity of the parent lipid A yet enjoys reduced toxicity. It has previously been reported that pretreatment with MLA reduces myocardial infarct size and stunning in dogs following ischemia and reperfusion. The aim of this study was to evaluate the ability of monophosphoryl lipid A (MLA) to preserve global cardiac function and peripheral hemodynamics in a rabbit model of prolonged regional ischemia (90 min), and reperfusion (6 h). An evaluation of potential mechanisms by which MLA may preserve cardiac function was also undertaken. Single dose pretreatment with MLA (35 micrograms/kg i.v.) 24 h prior to ischemia resulted in significant improvement in left ventricular developed pressure, dP/dt, rate-pressure product and mean arterial pressure during reperfusion (P < 0.05 v control). Although in this model of prolonged ischemia MLA pretreatment did not reduce infarct size (54.5 +/- 11.4% in control v 63.3 +/- 8.3% in MLA, P = N.S.), evaluation of myocardial adenylate and adenosine catabolite pools at the end of ischemia indicated a preservation of ATP and ADP and a decreased production of downstream adenosine catabolites including inosine, xanthine and uric acid. Adenosine kinase, but not 5'-nucleotidase (5'-NTase) or adenosine deaminase activity determined following reperfusion was 76% and 60% higher (P < 0.05) in non-risk and post-ischemic myocardium of MLA pretreated rabbits compared with controls. Although there was a trend toward lower tissue myeloperoxidase activity in post-ischemic myocardium from treated rabbits, the results were not significantly different from control animals. These results suggest that a 24-h pretreatment with MLA, without further treatment during ischemia or reperfusion was associated with: (1) preservation of global myocardial function during reperfusion; (2) preservation of myocardial high energy adenylates and reduced formation of adenosine catabolites during ischemia; (3) elevated myocardial adenosine kinase activity. Increased recycling of adenosine to phosphorylated nucleotides may result from MLA's affect on adenosine kinase, which could explain the drugs effect on adenylate and adenosine metabolite pools.     

Transcrystalline morphology of nylon 6 on the surface of aramid fibers

In this paper, the isothermal crystallization of nylon 6 in the presence of Kevlar 129 fiber was investigated by polarized optical microscopy (POM). The formation of a transcrystalline domain was found to be mainly controlled by crystallization conditions, such as the temperature of the isothermal crystallization, residual time at melting temperature and the cooling rate of the melt. The nucleation rate of nylon 6 on the fibers was mainly affected by the crystallization temperature. The interfacial transcrystallinity of nylon 6 occurred on the surface of Kevlar 129 fiber in the temperature range 130–190 °C. The reason for the formation of interfacial transcrystalline morphology is discussed from the molecular level, based on the understanding of the packing mode of nylon 6 chains around fibers and the interaction between matrix and fibers. It was found that the lattice matching and hydrogen‐bonding between nylon 6 and poly(p‐phenylene terephthalamide) (PPTA) crystals play an important role in the epitaxial crystallization. Copyright © 2004 Society of Chemical Industry     

Comparison of two oral evacuants (Citromag and Golytely) for bowel preparation before barium enema

Oral regimens for bowel preparation before barium enema examination are routinely used because of their convenience and simplicity, rather than the traditional method of colonic wash-out. We performed a prospective study comparing the side-effects and efficacy of two commonly used oral bowel evacuants (Citromag and Golytely) for bowel preparation before barium enema examination in 102 patients. The side-effects associated with the agents were assessed by analysing a questionnaire completed by the patients. There was no significant difference in the side-effects between the two agents although more patients taking Golytely (45.5%) deemed its taste unacceptable than those taking Citromag (25.9%). The results of the bowel preparation were assessed by two independent radiologists giving scores on the amount of faecal residue and the quality of mucosal coating. The amount of faecal residue was less in the Golytely group (p < 0.05). The quality of mucosal coating by barium was also better in the Golytely group than the Citromag group (p < 0.05).     

Effect of osteoarthritis in the lumbar spine and hip on bone mineral density and diagnosis of osteoporosis in elderly men and women

To select for bacterial strains with enhanced phenotypes, random fragments of a whole genome, or a defined region of the genome, are cloned in a nonreplicating vector. The resulting plasmids are integrated by recombination into the homologous DNA region of the original strain. Integration gives rise to a nontandem direct duplication of the corresponding DNA region separated by the vector moiety of the plasmid. Recombination between the direct repeats leads to tandem duplication and further amplification of the entire integrated DNA, including the vector. Bacteria harboring the amplified DNA are selected by increasing the dosage of an antibiotic corresponding to a resistance marker of the integrated vector. Pooled strains carrying amplifications are then challenged with a selective pressure for the desired phenotype. After repeated selection cycles, the most fit strains are isolated. We used this process, which we called random DNA amplification, to select Rhizobium strains with increased competitiveness for nodule formation. Derivatives containing randomly amplified DNA regions of the symbiotic plasmid of Rhizobium tropici CFN299 strain were generated. Pools of amplified strains were inoculated onto various tropical legumes. After several cycles of selection through plants, amplified derivatives showing an increased competitiveness for nodule formation with the leguminous plant Macroptilium atropurpureum were obtained.     

Homologous recombination of a flanking repeat gene cluster is a mechanism for a common contiguous gene deletion syndrome

Smith-Magenis syndrome (SMS), caused by del(17)p11.2, represents one of the most frequently observed human microdeletion syndromes. We have identified three copies of a low-copy-number repeat (SMS-REPs) located within and flanking the SMS common deletion region and show that SMS-REP represents a repeated gene cluster. We have isolated a corresponding cDNA clone that identifies a novel junction fragment from 29 unrelated SMS patients and a different-sized junction fragment from a patient with dup(17)p11.2. Our results suggest that homologous recombination of a flanking repeat gene cluster is a mechanism for this common microdeletion syndrome.     

A patient with Graves' disease, thrombocytopenia and chronic hepatitis B

A 22-year-old Chinese man, a HBsAg carrier, presented with relapse of thyrotoxic Graves' disease complicated by thrombocytopenia and hepatitis. Platelet count and liver enzymes gradually improved following successful treatment of the thyrotoxicosis with radioactive iodine. Possible pathogenetic links and therapeutic implications are discussed.