Radiofrequency ablation of large renal angiomyolipoma: median-term follow-up.

PURPOSE: To study the feasibility of percutaneous radiofrequency ablation (RFA) of large angiomyolipomas (AMLs) using saline-cooled electrodes. MATERIALS AND METHODS: Institutional Review Board approval for the study was received. Four patients (all female, age range 33-67 years) with large AMLs (maximal axis 6.1-32.4 cm) not suitable for embolotherapy or surgery consented to a trial of RFA. Procedures were performed under computerized tomographic guidance using 14G saline-infused electrodes. Two ablations (diameter 4-7 cm) were undertaken in each patient. Variables studied were technical success, treatment safety, alteration of tumor consistency, tumor size, effect on renal function, and medium-term freedom from haemorrhage. RESULTS: All four patients underwent successful RFA without any intraprocedural complications. There has been no haemorrhage, or new renal specific symptom, during a minimum 48-month period, and normal renal function has been normal. On follow-up radiological imaging, the tumors have become fattier with involution of the soft-tissue elements (soft tissue-to-total tumor ratio decreased mean [range] of 0.26 [0.14-0.48] to 0.17 [0.04-0.34] U; p = 0.04 [paired Student t test]). Further evidence of treatment effect was the development of a capsule around the ablation zone, but there was no change in overall tumor volume (mean [range] 1,120 [118-2,845] to 1150 [90-3,013] ml; p = 1 [paired Student t test]). CONCLUSION: RFA of large AMLs is technically feasible using saline-infused electrodes. The soft-tissue elements decreased in volume; the tumors become fattier; and there has been no renal haemorrhage during a 48-month period.

Deletion of the CSB homolog, RAD26, yields Spt(-) strains with proficient transcription-coupled repair.

It has been previously shown that disruption of RAD26 in yeast strain W303-1B results in a strain that is deficient in transcription-coupled repair (TCR), the preferential repair of the transcribed strand of an expressed gene over the non-transcribed strand and the rest of the genome. RAD26 encodes a protein that is homologous to Cockayne syndrome group B protein (CSB) and is a member of the SWI2/SNF2 family of DNA-dependent ATPases involved in chromatin remodeling. Like the rad26 mutant, cells from Cockayne syndrome patients are defective in TCR. We examined the role of Rad26 in TCR by disrupting RAD26 in two repair-proficient laboratory strains and, remarkably, observed no effect upon TCR. Our results indicate that disruption of RAD26 alone is insufficient to impair TCR. Thus, W303-1B must already possess a mutation that, together with disruption of RAD26, causes a deficiency in TCR. We suggest that other genes are mutated in Cockayne syndrome cells that contribute to the deficiency in TCR. Surprisingly, deletion of RAD26 results in expression of genes that are repressed by flanking transposon delta elements, an Spt(-) phenotype. The delta elements appear to perturb local chromatin structure. Expression of genes flanked by delta elements in rad26Delta mutants is consistent with a role for Rad26 in chromatin remodeling.

Transcription-coupled DNA repair in yeast transcription factor IIE (TFIIE) mutants.

We examined the role of yeast transcription initiation factor IIE (TFIIE) in eukaryotic transcription-coupled repair (TCR), the preferential removal of DNA damage from the transcribed strands of genes over non-transcribed sequences. TFIIE can recruit the transcription initiation/repair factor TFIIH to the RNA polymerase II (RNA pol II) initiation complex to facilitate promoter clearance. Following exposure to UV radiation, the RNA pol II elongation complex is blocked at sites of UV-induced DNA damage, and may be recognized by nucleotide excision repair proteins, thus enabling TCR. The TFA1 gene encodes the large subunit of TFIIE. We determined how DNA repair is affected by TFA1 conditional mutations. In particular, we find proficient TCR in a heat-sensitive tfa1 mutant at the non-permissive temperature during which growth is inhibited and overall RNA pol II transcription is reported to be inhibited. We demonstrate that transcription of the RPB2 gene was reduced, but readily detectable, in the heat-sensitive tfa1 mutant at the non-permissive temperature and thereby prove that TCR does occur in an expressed gene in the absence of TFIIE in vivo. We demonstrate that TCR occurs even at low levels of transcription.

The shock attenuation characteristics of four different insoles when worn in a military boot during running and marching.

A study was undertaken to determine if placing shock absorbing insoles in the boots of Royal Marine recruits would attenuate the peak pressure at the foot-boot interface, when marching at 4.8 kph carrying a 32 kg (70 lb) Bergen and running at 12.8 kph in loose order plus webbing weighing 10 kg (22 lb). Four types of insoles were assessed: viscoelastic polymetric insole (Cambion(R)) polymetric foam insole (PPT(R)) Saran insole (military issue) and Sorbothane(R). There was a fifth control condition in which no insoles were used. Pressure measurements during heel strike and forefoot loading were taken using Paratec equipment with pressure measuring insoles placed in the boots. Data were obtained from eleven subjects and indicated that all the insoles significantly (P<0.05) attenuated the peak pressures generated during heel strike and forefoot loading. The performance of the four insoles in terms of peak pressure attenuation ranked in order with the best first were: Sorbothane Cambion PPT Saran. The Sorbothane insole was substantially and significantly (P<0.05) better than the other insoles in terms of attenuating peak pressures during heel strike. During running, mean peak pressure at heel strike was 494 kPa in the control condition, this was reduced to 377 kPa when wearing Sorbothane insoles (a reduction of 27%). When marching the Sorbothane insoles reduced the mean peak pressure at heel strike from 395 kPa (control) to 303 kPa (23% reduction). During forefoot loading the peak pressure attenuation of all four insoles was similar, although on average the Sorbothane insole performed slightly better than the others and was significantly different (P<0. 05) to the Cambion insole. Mean peak forefoot loading pressure in the control condition when running was 413 kPa, with the Sorbothane insole it was 367 kPa, during marching the respective mean peak pressures were 397 and 323 kPa. It is concluded that of the four types of insoles assessed the Sorbothane insoles attenuated the greatest amounts of the peak pressure generated at heel strike and during forefoot loading when running and marching wearing military boots.