Chrome congestive heart failure: Radiofrequency ablation of accessory pathways: implications of accumulated experience and time dedicated to procedures

Previous reports on radiofrequency ablation of accessory pathwayshave shown that the experience of the operator is of crucialimportance in reducing fluoroscopy time and achieving highersuccess rates. However, a detailed analysis of this importantissue has not been previously attempted We analysed 71 consecutive ablation procedures undertaken atSt George's Hospital by the same electrophysiology group andalways with the same first operator. Of all procedures, 66 (916%)were successful, as judged by abolition of accessory pathwayconduction without recurrence within the next 24 h. Failuresincluded two out of 38 left-sided pathway procedures (5·3%),one out of 11 intermediate septal (9·1%) and four outof 22 right-sided pathway procedures (18·2%). These differencewere not statistically significant. Average procedure and screeningtimes for all procedures were 162·9±86·0min and 56·8±48·2 mm respectively, whereasthe median of the number of discharges was 12, ranging fromone to 51. There was no significant difference between pathwaygroups or between concealed and non-concealed pathways in respectto procedure and screening time or number of discharges. Therewas a significant tendency towards decreased procedure and screeningtimes with accwnulating experience and this was similar forall pathway groups. There was also a tendency towards improvedcwnulative success rates with time dedicated to procedures. We conclude that a certain amount of ablation experience isrequired, even by experienced electrophysiologists, before arelatively high success rate without long radiation exposurecan be achieved, regardless of the location or the mode of conductionof the pathway. Success rates increase with procedure time,suggesting that early abandonment of the procedure may resultin higher failure rates in diffcult cases.     

Prolonged suppression of spermatogenesis by oestrogen does not preserve the seminiferous epithelium in procarbazine-treated rats

We examined the hypothesis that induction of reversible testicular atrophy, subsequent to withdrawal of gonadotrophin support, would alleviate the testicular toxicity of the anti-cancer drug procarbazine. In rats, severe but reversible testicular atrophy and suppression of spermatogenesis were induced 56 days after the subcutaneous insertion of a silastic implant containing oestradiol-17 beta. The effect of this treatment upon the testicular toxicity of four weekly doses of procarbazine (200 mg kg-1) was examined 56 days after the termination of procarbazine/oestrogen treatment. At this time the testicular endocrine and spermatogenic functions were close to normal in rats which has received only oestradiol-17 beta. Procarbazine produced severe testicular atrophy which was associated with azoospermia and destruction of the germinal epithelium. Serum LH and FSH concentrations were raised and were associated with low serum concentrations of both testosterone and androgen-binding protein. The combination of procarbazine with the oestrogen treatment did not change any of the testicular toxicity and in some cases it appeared to be exacerbated. In contrast to these experiments other studies have indicated that the testis can be protected if spermatogenesis is reversibly suppressed by other agents which are also active via the pituitary endocrine system. The data would therefore suggest that protection is achieved either by some testicular change other than withdrawal of pituitary gonadotrophin support or that oestradiol-17 beta has additional activity which is permissive for the development of the testicular toxicity of procarbazine.     

Subgroups of smokers with different success rates after use of transdermal nicotine

To identify subgroups of smokers with different success rates, we applied "tree-structured survival analysis" (TSSA) to data from a previously published trial of transdermal nicotine. The subjects who received active treatment (14 mg patch, n 275, or the 21 mg patch, n 262) constituted the sample for this analysis. Using age, gender, the Fagerstrom Tolerance Questionnaire (FTQ), motivation to quit, number of cigarettes smoked at baseline, and body mass index (BMI) as classification variables, TSSA identified two subgroups within the 14 mg patch group and four subgroups of smokers within the 21 mg patch group. Among those receiving the 14 mg patch, individuals with a BMI greater than 26.4 kg/m relapsed sooner than did those with a BMI less than or equal to this value. Within the 21 mg patch group, the survival curve for males was significantly different from that observed in females, with males experiencing a longer time to relapse after treatment than did females. Among males, those who were less dependent relapsed significantly later than did those men who were more dependent. Among females, those with a higher motivation to quit relapsed more slowly than did those women with less motivation to quit. This information may be helpful to clinicians seeking to match specific patients to specific treatments with transdermal nicotine in order to maximize treatment outcomes.     

Progress in Rhesus Histocompatibility Typing Resulting from the Second International Nonhuman Primate Histocompatibility Workshop (1973)

The Second International Nonhuman Primate Histocompatibility Workshop permitted comparison of rhesus monkey alloantisera developd in various laboratories on a single common panel of related and unrelated monkeys. Analysis of the data permits the conclusion that at least nine specificities are recognized by more than one laboratory, including six at the first locus and three at the second locus.     

Mouse Liver Carcinogenesis: Mechanisms and Relevance

Symposium Overview: Mouse Liver Carcinogenesis: Mechanisms andRelevance. GOODMAN, J. I., WARD, J. M., POPP, J. A., KALUNIG,J. E., AND FOX, T. R. (1991). Fundam. Appl. Toxicol. 17, 651–665.