Radiofrequency Ablation of Symptomatic but Benign Ventricular Arrhythmias

Two cases are presented where ablation of severely symptomatic ventricular arrhythmias not responding to medical therapy was accomplished with radiofrequency current application. After a routine programmed stimulation protocol, a quadripolar ablation catheter with a 4-mm tip was advanced percutaneously into the left ventricle in one case and into the right ventricle in the second case; and after precise pace mapping, the arrhythmogenic focus was successfully ablated using radiofrequency current. The postablation ambulatory recording revealed virtual eradication of ventricular ectopy in both cases. In conclusion, in severely symptomatic cases of "benign" ventricular arrhythmias, radiofrequency ablation offers an effective therapeutic alternative.     

Firing behaviour in nerve cell models with a two-state pore system

The firing behaviour of simple nerve cell models with a two-state pore system was investigated by computer simulation. The pores were assumed to open and close randomly, with the probabilities for opening and closing calculated from the equations found by Hodgkin and Huxley for the squid giant axon. The cell models had a cell body and an axon with an initial segment with a smaller diameter. Both the case of a uniform membrane with constant pore densities all over the cell, and the case of a cell body membrane with only a leakage conductance (a ‘passive’ membrane) were investigated. The results indicate that the firing behaviour of a small nerve cell may be significantly influenced by the finite number of pores in the initial segment. In contrast to the original Hodgkin-Huxley equations which give a very non-linear frequency-current relationship in such nerve cell models, a fairly linear relationship over a large current range was found in many cases. It was estimated that the diameter of the initial segment must be less than approximately 1μm and the length larger than half a space constant, in order to obtain a current frequency relationship significantly different from that predicted by the original Hodgkin-Huxley equations.     

Unexpected lability of cysteine acetamidomethyl thiol protecting group Tyrosine ring alkylation and disulfide bond formation upon acidolysis

Cleavage and deprotection of the peptidyl resin H-Asn-Gly-Gly-Cys(Acm)-Glu(OBu^t)-Gln-Tyr(Bu^t)-Cys(Acm)-Ser(Bu^t)-Asp(OBu^t)-[(p-alkoxy)benzyloxy polystyrene resin] using standard conditions with various trifluoroacetic acid-containing mixtures were found to result in partial removal of ordinarily acid-stable S-Acm groups. Thus, apart from the desired peptide H-Asn-Gly-Gly-Cys(Acm)-Glu-Gln-Tyr-Cys(Acm)-Ser-Asp-OH, a disulfide-cyclic peptide derivative was also isolated. Furthermore, it was found that in another major by-product of the peptide resin cleavage the tyrosine side chain had been alkylated with an Acm group in a position ortho to the phenolic function. The formation of both by-products could be suppressed by carrying out the cleavage/deprotection reaction at higher dilution and by inclusion of scavengers such as phenol. An authentic sample of the disulfide-cyclic peptide was obtained by oxidation of H-Asn-Gly-Gly-Cys-Glu-Gln-Tyr-Cys-Ser-Asp-OH using Ellman's reagent. © Munksgaard 1997.     

Human odontogenic keratocyst transplants in nude mice

Abstract – Specimens from human odontogenic keratocysts were subcutaneously transplanted to nude mice. The transplants were harvested after 14–66 d with a rate of successful recovery of 87%. The histologic epithelial features in the original odontogenic keratocyst and their transplants were essentially similar. This included a well-defined basal cell layer composed of columnar and cuboidal cells, the number of cell layers and die keratinization pattern. Epithelial outgrowths from the transplants were found in 19 of 26 cases. The outgrowths over murine connective tissue in the majority of cases were keratinized, but the phenotypic expression differed with respect to the shape of basal cells and number of cell layers.     

INCREASED EXPRESSION OF IL-15 IN THE SYNOVIUM OF PATIENTS WITH RHEUMATOID ARTHRITIS COMPARED WITH PATIENTS WITH YERSINIA-INDUCED ARTHRITIS AND OSTEOARTHRITIS

Recently, a new player in the cytokine network has been described that is produced by monocytes and can be detected in the rheumatoid synovium: interleukin-15 (IL-15). Since this cytokine may play a role in the accumulation and activation of T-cells, B-cells, and natural killer (NK) cells characteristic of synovial tissue (ST) from patients with rheumatoid arthritis (RA), the expression of IL-15 was studied in ST from RA patients in comparison with ST from patients with reactive arthritis (ReA) and osteoarthritis (OA) and the phenotype of IL-15-positive cells was determined. IL-15 expression was investigated by immunohistochemical analysis of ST from ten patients with RA, ten patients with Yersinia enterocolitica-induced ReA, and nine patients with OA. The immunohistological findings were quantified and the results obtained in the different patient groups were compared. To determine the phenotype of IL-15-expressing cells, double-labelling immunofluorescence was performed. The expression of IL-15 was significantly higher in ST from patients with RA than in ST from patients with ReA or OA. In double-label experiments, co-expression was observed with markers for macrophages, T-cells, and NK cells. The composition of the cellular infiltrate in the synovium of patients with RA might be partly explained by the specific increase in expression of IL-15 in rheumatoid ST. It can be speculated that IL-15 production by inflammatory cells other than macrophages may occur in the rheumatoid synovium. © 1997 by John Wiley & Sons, Ltd.     

Emergence of fluoroquinolone‐resistant clonal group A: clonal analysis of Norwegian and Russian E. coli isolates

Strand L, Jenkins A, Grude N, Allum A‐G, Mykland H‐C, Nowrouzian FL, Kristiansen B‐E. Emergence of fluoroquinolone‐resistant clonal group A: clonal analysis of Norwegian and Russian E. coli isolates. APMIS 2010; 118: 571–77. We describe a study of urinary tract and intestinal isolates of Escherichia coli from Norway and Russia using automated ribotyping, single nucleotide polymorphism analysis for clonal group A (CgA) supplemented with phylogrouping, virulence gene profiling and resistance profiling. CgA comprised 19% of the Norwegian UTI isolates from 2001. Two highly multiresistant fluoroquinolone‐resistant CgA isolates were found. Ribotypes clustered into four major and six minor groups (ribogroups). Fluoroquinolone‐resistant isolates and phylogroups A and B1 were associated with ribogroup ^RA. Ribogroup ^RB predominated among Russian UTI isolates and was predominantly phylogroup A and depleted in P‐fimbriae. Ribogroup ^RC predominated among Norwegian UTI isolates and was rich in virulence factors (S‐fimbriae, haemagglutinin and haemolysin) and predominantly phylogroup B2 and D. Ribogroup ^RG was associated with CgA and predominantly phylogroup D. Ribogroups ^RD, ^RE and ^RF had too few members for statistical analysis. The correlation between ribotype and phylogenetic group was not as strong as reported in other studies.     

Sibling sex ratio of individuals diagnosed with autism spectrum disorder as children

Aim To study the sex ratio (proportion of males) in siblings of individuals diagnosed with autism spectrum disorders (ASDs) as children. Method In the current study, we extended previous studies dealing with the androgen theory of autism and examined sex ratios in the siblings of 326 individuals with ASD (245 males, 81 females) who had been consecutively assessed at two Danish university clinics of child psychiatry during the 25‐year period from 1960 to 1985. Results Among the 513 siblings, 300 were males and 213 females. This yields a sex ratio of 0.585, which is significantly higher than the Danish live‐birth sex ratio over the same period (0.514, p=0.001). The sibling sex ratio was not associated with the IQ in the autistic probands. Interpretation Our findings suggest a potential indirect confirmation of the androgen theory of autism.