Prognostic factors associated with clear cell sarcoma in 14 Chinese patients.

PURPOSE. To identify prognostic factors associated with clear cell sarcomas in 14 Chinese patients. METHODS. Medical records of 7 men and 7 women (mean age, 36 years) with histologically confirmed clear cell sarcoma of tendons and aponeuroses were reviewed. Patient demographics, tumour characteristics, and treatment modalities were retrieved. Prognostic factors associated with favourable 5-year survival were determined. RESULTS. The most affected sites were the thigh (n=5) and the foot (n=4); the mean time from symptom onset to diagnosis was 9.5 months. The tumour stage at diagnosis was IIA in 8 patients, IIB in 2, and III in 4. The mean tumour size was 4.5 cm in diameter. One patient was lost to follow-up. For the remaining 13 patients, the mean time to disease-related mortality was 2.5 years. Nine patients had distant metastases; the most common sites were lungs and pleura (n=7), followed by distant lymph nodes (n=4), bone (n=2), pericardium (n=2), and brain (n=1). All patients underwent surgical excision. Three women and one man (mean age, 27 years) attained 5-year disease-free survival. All had stage IIA tumours at diagnosis. Their mean tumour size was 1.75 cm in diameter, which was significantly smaller than that of all patients (4.5 cm). Tumour size of ≤ 2.5 cm in diameter (p=0.004) and stage IIA tumour at diagnosis (p=0.04) were significant prognostic factors for 5-year survival. CONCLUSION. Tumour size of ≤ 2.5 cm and early stage tumour are associated with 5-year disease-free survival. Early detection is crucial for the prognosis of clear cell sarcomas.

A modified periungual approach for treatment of subungual glomus tumour.

Subungal glomus tumours are uncommon; the only treatment is complete surgical excision. Transungual approach is often preferred; however, secondary nail deformity may occur. Lateral periungual approach is used to avoid this complication, but this approach provides limited exposure and is used for peripheral lesion only. We describe a modified periungual approach which can be applied to central lesions. This approach can provide adequate exposure for complete excision of the subungual tumour while avoiding incision of the nail bed.

Loss of function of the homeobox gene Hoxa-9 perturbs early T-cell development and induces apoptosis in primitive thymocytes.

Hox homeobox genes play a crucial role in specifying the embryonic body pattern. However, a role for Hox genes in T-cell development has not been explored. The Hoxa-9 gene is expressed in normal adult and fetal thymuses. Fetal thymuses of mice homozygous for an interruption of the Hoxa-9 gene are one eighth normal size and have a 25-fold decrease in the number of primitive thymocytes expressing the interleukin-2 receptor (IL-2R, CD25). Progression to the double positive (CD4+CD8+) stage is dramatically retarded in fetal thymic organ cultures. This aberrant development is associated with decreased amounts of intracellular CD3 and T-cell receptor beta (TCRbeta) and reduced surface expression of IL-7R and E-cadherin. Mutant thymocytes show a significant increase in apoptotic cell death and premature downregulation of bcl-2 expression. A similar phenotype is seen in primitive thymocytes from adult Hoxa-9-/- mice and from mice transplanted with Hoxa-9-/- marrow. Hoxa-9 appears to play a previously unsuspected role in T-cell ontogeny by modulating cell survival of early thymocytes and by regulating their subsequent differentiation.

Direct selection of tetracycline-sensitive Escherichia coli cells using nickel salts.

In this report, a new method for the selection of tetracycline-sensitive Escherichia coli cells from a mixed population is described. This method is simpler and more effective than previous methods, does not utilize toxic reagents, and allows selection in liquid as well as solid media. This method should be of considerable aid in molecular cloning procedures involving inactivation of the tetracycline-resistance genes encoding the energy-dependent efflux of the antibiotic, as well as in the study of the function of tetracycline-resistance elements such as transposons and integrons.

Molecular genetics of a chromosomal locus involved in copper tolerance in Escherichia coli K-12.

The cutA locus, presumably involved in copper tolerance in Escherichia coli, was characterized by a mutation leading to copper sensitivity. Copper-accumulation measurements with radioactive 64Cu2+ showed increased uptake by cutA copper-sensitive mutant cells, and reduced uptake when the cutA mutation was complemented in trans. The locus was mapped using complementation of the cutA mutant to partial copper tolerance with wild-type chromosomal fragments. The 3.2 kb DNA region involved in cutA was sequenced and analysed, revealing three significant open reading frames, none of which had been previously published. The products of all three open reading frames were identified, when synthesized with the T7 phage promoter expression system, as polypeptides of about 50 kDa, 24 kDa, and 13 kDa, consistent with the sizes predicted from the DNA sequences. The 50 kDa and 24 kDa polypeptides were found in the bacterial inner membrane, and the 13 kDa polypeptide with the cytoplasmic fraction. In addition to being required for copper tolerance, cutA affects tolerance levels to zinc, nickel, cobalt and cadmium salts. Transcriptional fusions of cutA with the lux operon showed induction by copper, zinc, nickel, cobalt and, to a lesser extent, cadmium, manganese and silver salts.

Identification and characterization of RP1 Tra1 cistrons involved in pilus function and plasmid mobilization.

Transfer-defective mutants of the Tra1 region of RP1 were isolated. Complementation studies involving stable heterozygotes combined with the mapping of Tn5 insertion mutations revealed two pilus cistrons, pilA and pilB, at positions 46.9 to 48.2 kb and 46.0 to 46.4 kb, respectively. All pilB mutants were Dps- (i.e., resistant to donor-specific phages PR4 and PRR1), whereas pilA mutants were Dps- (promoter-proximal mutations), Dps+/- (sensitive only to PR4 [more centrally located mutations]), or Dps+ (sensitive to both phages [promoter-distal mutations]). The correlation between the site mutated and the Dps phenotype, together with the finding that certain Dps+ pilA mutants continued to mobilize nonconjugative plasmids, suggested that pilA is bifunctional, contributing both to pilus function (at the promoter-proximal end) and to RP1 mobilization. It was also shown that the 43.5- to 49.5-kb region that includes pilA and pilB encodes all of the Tra1 pilus functions required for propagation of donor-specific phages and hence, probably, for pili that are active in conjugation. Finally, three cistrons that specifically affect RP1 mobilization were identified. Two of these, mobA and mobB, occur immediately anticlockwise to oriT and probably correspond to the traJ and traI genes characterized by other workers. The third cistron, mobC, occurs clockwise to oriT and may be a new mobilization gene, since its function can be substituted by IncP beta plasmids, a feature different from that of the traK mobilization gene which occurs in the same region but is RP1 specific. None of the mob cistrons was required for mobilization of nonconjugative plasmids, except for mobB, which was required by pVS99.

Location and characterization of two functions on RP1 that inhibit the fertility of the IncW plasmid R388.

Two fertility-inhibition functions which reduce R388 (IncW) transfer were detected on RP1 (60 kb, IncP). The respective genes, fiwA and fiwB, were mapped by transposon insertion mutagenesis to the regions between coordinates 32.8 to 31.7 kb (fiwA), and 59.8 to 0.8 kb (fiwB). The fiwA function occurs in a non-essential region of RP1 whereas fiwB is straddled by essential plasmid-maintenance and host-range determinants and apparently coincides (or overlaps) with the gene for tellurite-resistance.