In vitro activity of Bay 12-8039, a new 8-methoxyquinolone, compared to the activities of 11 other oral antimicrobial agents against 390 aerobic and anaerobic bacteria isolated from human and animal bite wound skin and soft tissue infections in humans

The in vitro activity of Bay 12-8039, a new oral 8-methoxyquinolone, was compared to the activities of 11 other oral antimicrobial agents (ciprofloxacin, levofloxacin, ofloxacin, sparfloxacin, azithromycin, clarithromycin, amoxicillin clavulanate, penicillin, cefuroxime, cefpodoxime, and doxycycline) against 250 aerobic and 140 anaerobic bacteria recently isolated from animal and human bite wound infections. Bay 12-8039 was active against all aerobic isolates, both gram-positive and gram-negative isolates, at < or = 1.0 microg/ml (MICs at which 90% of isolates are inhibited [MIC90s < or = 0.25 microg/ml) and was active against most anaerobes at < or = 0.5 microg/ml; the exceptions were Fusobacterium nucleatum and other Fusobacterium species (MIC90s, > or = 4.0 microg/ml) and one strain of Prevotella loeschii (MICs, 2.0 microg/ml). In comparison, the other quinolones tested had similar in vitro activities against the aerobic strains but were less active against the anaerobes, including peptostreptococci, Porphyromonas species, and Prevotella species. The fusobacteria were relatively resistant to all the antimicrobial agents tested except penicillin G (one penicillinase-producing strain of F. nucleatum was found) and amoxicillin clavulanate.     

Phenotypic heterogeneity of mutational changes at a conserved nucleotide in 16 S ribosomal RNA

RNA sites that contain unpaired or mismatched nucleotides can be interaction sites for other macromolecules. C1054, a virtually universally conserved nucleotide in the 16 S (small subunit) ribosomal RNA of Escherichia coli, is part of a highly conserved bulge in helix 34, which has been located at the decoding site of the ribosome. This helix has been implicated in several translational events, including peptide chain termination and decoding accuracy. Here, we observed interesting differences in phenotype associated with the three base substitutions at, and the deletion of, nucleotide C1054. The phenotypes examined include suppression of nonsense codons on different media and at different temperatures, lethality conditioned by temperature and level of expression of the mutant rRNA, ribosome profiles upon centrifugation through sucrose density gradients, association of mutant 30 S subunits with 50 S subunits, and effects on the action of tRNA suppressor mutants. Some of our findings contradict previously reported properties of individual mutants. Particularly notable is our finding that the first reported 16 S rRNA suppressor of UGA mutations was not a C1054 deletion but rather the base substitution C1054A. After constructing deltaC1054 by site-directed mutagenesis, we observed, among other differences, that it does not suppress any of the trpA mutations previously reported to be suppressed by the original UGA suppressor. In general, our results are consistent with the suggestion that the termination codon readthrough effects of mutations at nucleotide 1054 are the result of defects in peptide chain termination rather than of decreases in general translational accuracy. The phenotypic heterogeneity associated with different mutations at this one nucleotide position may be related to the mechanisms of involvement of this nucleotide, the two-nucleotide bulge, and/or helix 34 in particular translational events. In particular, previous indications from other laboratories of conformational changes associated with this region are consistent with differential effects of 1054 mutations on RNA-RNA or RNA-protein interactions. Finally, the association of a variety of phenotypes with different changes at the same nucleotide may eventually shed light on speculations about the coevolution of parts of ribosomal RNA with other translational macromolecules.     

Unilateral vs. bilateral carpal tunnel: challenges and approaches

Conditions affecting either or both extremities offer unique opportunities and challenges for investigators and clinicians. When the condition is purely unilateral, observations on the unaffected extremity may be used as a within-patient control, and thereby strengthen the ability to identify changes in the affected limb. However, such use presumes that the condition will not subsequently develop in the unaffected extremity. Bilateral presentations or subsequent development of disease in the unaffected extremity is common in conditions such as the carpal tunnel syndrome (CTS). Treatment of one extremity may lead to development or aggravation of CTS in the other extremity. Since both extremities may be necessary to perform certain activities, it can be difficult to clearly identify treatment effects when looking at functional outcomes. In an effort to avoid these complexities, investigators have used one of two approaches in studying CTS: either selecting only those patients with unilateral disease, or analyzing results by extremity, often avoiding any outcome measures that might depend upon both extremities (such as driving). We illustrate some of the shortcomings of this approach, such as loss of patients and data, with preliminary information from our ongoing prospective study of carpal tunnel surgery outcomes. We develop a dynamic model that incorporates etiologic factors and treatment effects to describe changes in CTS over time. This model accounts for extremity-specific and systemic factors, as well as possible interaction of the disease process in both hands. The advantages of this model include a more rational approach to research and care of extremity disorders, and research strategies which address a wider scope of patients and outcomes; however, its application is limited by the need for more extensive data collection.     

High-dose chemotherapy with autologous hematopoietic progenitor-cell support as part of combined modality therapy in patients with inflammatory breast cancer

PURPOSE: To evaluate the feasibility of high-dose chemotherapy (HDC) with autologous hematopoietic progenitor-cell support (AHPCS) as part of combined modality therapy (CMT) in patients with inflammatory breast cancer (IBC). PATIENTS AND METHODS: From April 1993 to March 1997, 30 patients with IBC were treated at our program. Twenty-three patients received neoadjuvant chemotherapy (NAC) before HDC; 18 patients also received adjuvant chemotherapy following surgery, but before HDC. All patients received HDC with high-dose cyclophosphamide, cisplatin, and carmustine (BCNU) with AHPCS. Every patient underwent surgery either before (27 patients) or after (three patients) HDC. Patients received radiotherapy after HDC in addition to tamoxifen if their tumors were estrogen receptor-positive. RESULTS: Thirteen patients experienced grade 3 or 4 nonhematologic noninfectious toxicities. In 12 patients (40%), this represented drug-induced lung injury, which in all cases responded to a 10-week course of corticosteroids. The only treatment-related death was secondary to hemolytic-uremic syndrome (HUS). Another patient suffered grade 4 CNS toxicity, which was completely reversible. All patients engrafted promptly. Eight patients relapsed, five of whom had a poor pathologic response to NAC. Relapses were local (five patients), local plus systemic (one), or systemic only (two). Median follow-up time from diagnosis and HDC is 23.5 (range, 7 to 49) and 19 (range, 4 to 44) months, respectively. Twenty-one patients (70%; 95% confidence interval [CI], 51% to 86%) remain alive and free of disease 4 to 44 months after HDC. Median disease-free survival (DFS) and overall survival have not yet been reached. CONCLUSION: HDC as part of CMT is feasible in patients with IBC. The toxicity of this treatment program is significant, but tolerable. Despite the short follow-up duration, the promising DFS observed in this group of patients warrants randomized studies that include a HDC-containing arm in patients with IBC.     

Single-strand breaks, cell cycle arrest and apoptosis in HL-60 and LLCPK1 cells exposed to 1,2-dibromo-3-chloropropane

We investigated 1,2-dibromo-3-chloropropane (DBCP)-induced DNA damage, cell cycle alterations and cell death in two cell lines, the human leukemia HL-60 and the pig kidney LLCPK1, both of which are derived from potential target sites for DBCP-induced toxicity. DBCP (30-300 micromol/L) caused a concentration-dependent increase in the levels of DNA single-strand breaks in both cell lines as well as in cultured human renal proximal tubular cells. After extended DBCP exposure in LLCPK1 cells (100 micromol/L, 30 h), the level of DNA breaks returned almost to control values. Incubation for 48 h showed a clear reduction of growth with DBCP concentrations as low as 10 micromol/L. Flow cytometric analysis showed that DBCP (1-10 micromol/L) exposure for 24 h caused an accumulation of LLCPK1 cells in the G2/M-phase. In HL-60 cells the accumulation in G2/M-phase was less marked, and at higher concentrations the cells accumulated in S-phase. Flow cytometric studies of HL-60 and LLCPK1 cells exposed to 100-500 micromol/L DBCP showed increased number of apoptotic cells/bodies with a lower DNA content than that of the G1 cells. Microscopic studies revealed that there were increased numbers of cells with nuclear condensation and fragmentation, indicating that apoptosis was the dominant mode of death in these cell lines, following exposure to DBCP. The characteristic ladder pattern of apoptotic cells was observed when DNA from DBCP-treated HL-60 cells and LLCPK1 cells was electrophoresed in agarose. The finding that DBCP can cause an accumulation of cells in G2/M-phase and induce apoptosis in vitro may be of importance for the development of DBCP-induced toxicity in vivo.     

Detection of Cryptosporidium oocysts and Giardia cysts in the tissues of eastern oysters (Crassostrea virginica) carrying principal oyster infectious diseases

The potential cross-reactivity of the combined Cryptosporidium/Giardia direct immunofluorescence antibodies (IFA) of MERIFLUOR and HYDROFLUOR-COMBO tests was examined against tissues containing known developmental stages of 12 pathogens causing the principal infectious diseases in oysters. Spores of Haplosporidium nelsoni and Haplosporidium costale produced positive acid-fast stain (AFS) reactions similar in intensity to Cryptosporidium parvum oocysts. Hexamia nelsoni trophozoites produced positive IFA reactions in both IFA tests; however, the intensity of fluorescence was considerably lower and the fluorescein-staining pattern different than those of Giardia cysts. The applicability of AFS for screening oysters for Cryptosporidium oocysts is low, and positive identification of Cryptosporidium oocysts cannot be accomplished based on the AFS. Presumptive IFA identification of the Cryptosporidium oocysts or Giardia cysts in the oyster tissue should fulfill 3 criteria, i.e., bright-green fluorescence of the same intensity as C. parvum oocysts and Giardia cysts in the positive control, correct size and shape of the fluorescein-stained objects, and oocyst or cyst shell clearly visible.