Is section of the sympathetic rami communicantes by laparoscopy in patients with refractory low back pain efficient?

OBJECTIVE: The objective of this prospective innovative treatment is to section the pain pathways carried by sympathetic lumbar rami communicantes to achieve lasting pain relief of refractory low back pain. METHODS: From December 2005 to September 2008, nine patients were operated by bilateral section of rami communicantes for a refractory low back pain. As a diagnostic and predictive test, all patients had, before surgery, a local anaesthetic infiltration of the sympathetic trunk at L2 performed with computed tomography guidance. Surgery is indicated if the tests lead to a reduction in pain of at least 50 %. The procedure, using a retroperitoneal laparoscopic approach, consisted to identify the sympathetic trunk and to section all lumbar rami communicantes from L1 to L2. RESULTS: No intraoperative complications were observed. The mean postoperative follow-up was 29 ± 15 months. At the last follow-up, only 22 % (2/9) patients had an improvement of their low back pain with this surgery but with a minimal effect (30 and 50 % reduction of pain). An improvement of quality of life was observed in 33 % (3/9) of cases. Due to persistent pain, four patients had a spinal cord stimulation after this surgery. CONCLUSIONS: Section the pain pathways carried by sympathetic lumbar rami communicantes for refractory low back pain improved 22 % of patients at the last follow-up of 29 months.

Functional results after tape removal for chronic pelvic pain following tension-free vaginal tape or transobturator tape.

PURPOSE: The incidence of pelvic pain after placement of a suburethral sling for incontinence ranges between 0% and 30%. The management of this chronic pain after suburethral sling placement is complex and to our knowledge no consensus has been reached. We evaluated the functional results after removal of the suburethral tape responsible for chronic pelvic pain. MATERIALS AND METHODS: From November 2004 to August 2009, 32 patients undergoing removal of suburethral tape causing chronic pelvic and perineal pain at our department were prospectively followed. Patients were divided according to the type of suburethral sling into the transobturator tape group (15 patients) and the tension-free vaginal (retropubic) tape group (17 patients). In the TVT group tape removal was performed using transperitoneal laparoscopy in every patient. In the TOT group tape removal was performed via a transvaginal approach possibly associated with a unilateral or bilateral incision in the proximal part of the thigh. Pain was evaluated by a visual analogue scale from 0-no pain to 10-maximal pain. RESULTS: The surgical exploration of suburethral tape responsible for chronic, treatment refractory pelvic pain revealed in most cases an abnormal tape position or excessive tape traction. In the overall population tape removal provided improvement of pain (at least 50% improvement of the visual analogue scale score) in 68% with a mean followup of 10 months. Mean visual analogue scale score was 7.3 +/- 1.5 before surgery and 3.4 +/- 3 after surgery. However, recurrence of incontinence was observed in 22% of cases. No significant difference was demonstrated in terms of functional results according to the type of tape insertion. CONCLUSIONS: The surgical removal of suburethral tape improved pain in 68% of patients but with a risk of recurrence of urinary incontinence in 22%.

Intraspecific variability of the terminal inverted repeats of the linear chromosome of Streptomyces ambofaciens.

The sequences of the terminal inverted repeats (TIRs) ending the linear chromosomal DNA of two Streptomyces ambofaciens strains, ATCC23877 and DSM40697 (198 kb and 213 kb, respectively), were determined from two sets of recombinant cosmids. Among the 215 coding DNA sequences (CDSs) predicted in the TIRs of strain DSM40697, 65 are absent in the TIRs of strain ATCC23877. Reciprocally, 45 of the 194 predicted CDSs are specific to the ATCC23877 strain. The strain-specific CDSs are located mainly at the terminal end of the TIRs. Indeed, although TIRs appear almost identical over 150 kb (99% nucleotide identity), large regions of DNA of 60 kb (DSM40697) and 48 kb (ATCC23877), mostly spanning the ends of the chromosome, are strain specific. These regions are rich in plasmid-associated genes, including genes encoding putative conjugal transfer functions. The strain-specific regions also share a G+C content (68%) lower than that of the rest of the genome (from 71% to 73%), a percentage that is more typical of Streptomyces plasmids and mobile elements. These data suggest that exchanges of replicon extremities have occurred, thereby contributing to the terminal variability observed at the intraspecific level. In addition, the terminal regions include many mobile genetic element-related genes, pseudogenes, and genes related to adaptation. The results give insight into the mechanisms of evolution of the TIRs: integration of new information and/or loss of DNA fragments and subsequent homogenization of the two chromosomal extremities.

Evolution of the terminal regions of the Streptomyces linear chromosome.

Comparative analysis of the Streptomyces chromosome sequences, between Streptomyces coelicolor, Streptomyces avermitilis, and Streptomyces ambofaciens ATCC23877 (whose partial sequence is released in this study), revealed a highly compartmentalized genetic organization of their genome. Indeed, despite the presence of specific genomic islands, the central part of the chromosome appears highly syntenic. In contrast, the chromosome of each species exhibits large species-specific terminal regions (from 753 to 1,393 kb), even when considering closely related species (S. ambofaciens and S. coelicolor). Interestingly, the size of the central conserved region between species decreases as the phylogenetic distance between them increases, whereas the specific terminal fraction reciprocally increases in size. Between highly syntenic central regions and species-specific chromosomal parts, there is a notable degeneration of synteny due to frequent insertions/deletions. This reveals a massive and constant genomic flux (from lateral gene transfer and DNA rearrangements) affecting the terminal contingency regions. We speculate that a gradient of recombination rate (i.e., insertion/deletion events) toward the extremities is the force driving the exclusion of essential genes from the terminal regions (i.e., chromosome compartmentalization) and generating a fast gene turnover for strong adaptation capabilities.

Conjugal immunity of Streptomyces strains carrying the integrative element pSAM2 is due to the pif gene (pSAM2 immunity factor).

Mechanisms of conjugal immunity preventing redundant exchange between two cells harbouring the same conjugative element have been reported in diverse bacteria. Such a system does exist for pSAM2, a conjugative and integrative element of Streptomyces. The apparition of the conjugative free form of pSAM2 in the donor strain during mating can be considered as the initial step of transfer. We analysed the genes involved in transfer inhibition by mating donors harbouring pSAM2 with recipient strains containing different regions of pSAM2. The conjugal immunity was previously thought to be mediated by the transcriptional repressor KorSA. Although the transfer efficiency is reduced by its presence in the recipient, the initiation of the transfer process is not affected. In contrast, the presence in the recipient strain of a single pSAM2 gene, pif (pSAM2 immunity factor), was sufficient to abolish both transfer and initiation of transfer. Thus, the clustered genes korSA and pif act complementarily to maintain pSAM2 in a 'prophage' state under non-conjugal conditions. KorSA is involved in intracellular signalling, whereas Pif participates in intercellular signalling. The Pif nudix motif is essential for its activity. This is the first protein of the nudix family shown to be involved in bacterial conjugation.

Recombinant environmental libraries provide access to microbial diversity for drug discovery from natural products.

To further explore possible avenues for accessing microbial biodiversity for drug discovery from natural products, we constructed and screened a 5,000-clone "shotgun" environmental DNA library by using an Escherichia coli-Streptomyces lividans shuttle cosmid vector and DNA inserts from microbes derived directly (without cultivation) from soil. The library was analyzed by several means to assess diversity, genetic content, and expression of heterologous genes in both expression hosts. We found that the phylogenetic content of the DNA library was extremely diverse, representing mostly microorganisms that have not been described previously. The library was screened by PCR for sequences similar to parts of type I polyketide synthase genes and tested for the expression of new molecules by screening of live colonies and cell extracts. The results revealed new polyketide synthase genes in at least eight clones. In addition, at least five additional clones were confirmed by high-pressure liquid chromatography analysis and/or biological activity to produce heterologous molecules. These data reinforce the idea that exploiting previously unknown or uncultivated microorganisms for the discovery of novel natural products has potential value and, most importantly, suggest a strategy for developing this technology into a realistic and effective drug discovery tool.

Characterization of the attP site of the integrative element pSAM2 from Streptomyces ambofaciens.

pSAM2 is integrated into the Streptomyces ambofaciens chromosome through site-specific recombination between the element (attP) and the chromosomal (attB) site. The 43 kDa integrase protein encoded by pSAM2 catalyses this recombination event. Tools have been developed to study site-specific recombination in Escherichia coli. In vivo studies showed that a 360 bp fragment of attP is required for efficient site-specific recombination and that int can be provided in trans. pSAM2 integrase was purified and overexpressed in E. coli and Int binding at the attP site was studied. DNaseI footprinting revealed two sites that bind integrase strongly and appear to be symmetrical with regard to the core site. These two P1/P2 arm-type sites both contain a 17 bp motif that is identical except at one position, GTCACGCAG(A/T)TAGACAC. P1 and P2 are essential for site-specific recombination.