Nitrofurantoin retains antimicrobial activity against multidrug-resistant urinary Escherichia coli from US outpatients.

OBJECTIVES: To examine the prevalence of multidrug-resistant (MDR) urinary Escherichia coli among US outpatients and to assess the antimicrobial activity of oral antibiotics commonly used to treat urinary tract infections (UTIs) against MDR isolates. METHODS: Antimicrobial susceptibility testing data from outpatient urine cultures in The Surveillance Network (TSN) Database USA were analysed. Six antimicrobial agents from six separate drug classes were included: ampicillin, cefalotin, ciprofloxacin, nitrofurantoin, trimethoprim/sulfamethoxazole and amoxicillin/clavulanate. Isolates were categorized as resistant to one, two, three, four, five and six agents and compared for the years 2001 and 2010. Phenotypes of MDR isolates were assessed to determine antimicrobial activity of recommended therapy for UTIs. RESULTS: Prevalence of MDR E. coli increased from 9.1% in 2001 (n = 29,198) to 17.0% in 2010 (n = 32,742) (P < 0.0001). In isolates that demonstrated resistance to three, four or five antimicrobial agents in 2010, resistance to nitrofurantoin was observed in only 2.1%, 7.5% and 24.1% of isolates, respectively. Conversely, widespread resistance was observed for trimethoprim/sulfamethoxazole (62.6%, 88.6% and 97.9% for isolates resistant to three, four and five agents, respectively) and ciprofloxacin (48.9%, 84.3% and 98.2% for isolates resistant to three, four and five agents, respectively). CONCLUSIONS: Because of its consistent antimicrobial activity against MDR E. coli, nitrofurantoin remains a reliable first-line agent for the empirical treatment of acute uncomplicated cystitis.

Interleukin 7 receptor control of T cell receptor gamma gene rearrangement: role of receptor-associated chains and locus accessibility.

VDJ recombination of T cell receptor and immunoglobulin loci occurs in immature lymphoid cells. Although the molecular mechanisms of DNA cleavage and ligation have become more clear, it is not understood what controls which target loci undergo rearrangement. In interleukin 7 receptor (IL-7R)alpha-/- murine thymocytes, it has been shown that rearrangement of the T cell receptor (TCR)-gamma locus is virtually abrogated, whereas other rearranging loci are less severely affected. By examining different strains of mice with targeted mutations, we now observe that the signaling pathway leading from IL-7Ralpha to rearrangement of the TCR-gamma locus requires the gammac receptor chain and the gammac-associated Janus kinase Jak3. Production of sterile transcripts from the TCR-gamma locus, a process that generally precedes rearrangement of a locus, was greatly repressed in IL-7Ralpha-/- thymocytes. The repressed transcription was not due to a lack in transcription factors since the three transcription factors known to regulate this locus were readily detected in IL-7Ralpha-/- thymocytes. Instead, the TCR-gamma locus was shown to be methylated in IL-7Ralpha-/- thymocytes. Treatment of IL-7Ralpha-/- precursor T cells with the specific histone deacetylase inhibitor trichostatin A released the block of TCR-gamma gene rearrangement. This data supports the model that IL-7R promotes TCR-gamma gene rearrangement by regulating accessibility of the locus via demethylation and histone acetylation of the locus.

The role of cytokine receptor signaling in lymphocyte development.

Cytokine receptor signaling plays an essential role in the early stages of lymphocyte development. Signals through various cytokine receptors - such as c-kit, flt3/flk2, CXCR4, the IL-7 receptor and the IL-15 receptor - are known to promote the expansion and survival of uncommitted progenitor cells as well as their migration to the appropriate microenvironment and subsequent differentiation into B, T or natural killer cells. The recent generation of mice deficient in one or more of these signaling pathways has revealed which cytokines play unique and/or redundant roles in each of these lymphocyte lineages during this developmental process.

CD28 and the tyrosine kinase lck stimulate mitogen-activated protein kinase activity in T cells via inhibition of the small G protein Rap1.

Proliferation of T cells via activation of the T-cell receptor (TCR) requires concurrent engagement of accessory costimulatory molecules to achieve full activation. The best-studied costimulatory molecule, CD28, achieves these effects, in part, by augmenting signals from the TCR to the mitogen-activated protein (MAP) kinase cascade. We show here that TCR-mediated stimulation of MAP kinase extracellular-signal-regulated kinases (ERKs) is limited by activation of the Ras antagonist Rap1. CD28 increases ERK signaling by blocking Rap1 action. CD28 inhibits Rap1 activation because it selectively stimulates an extrinsic Rap1 GTPase activity. The ability of CD28 to stimulate Rap1 GTPase activity was dependent on the tyrosine kinase Lck. Our results suggest that CD28-mediated Rap1 GTPase-activating protein activation can help explain the augmentation of ERKs during CD28 costimulation.

T cell development and activation in Jak3-deficient mice.

Jak3, a member of the Janus family of tyrosine kinases, participates in signaling through cytokine receptors that contain the common gamma-chain, including the receptors for interleukin (IL)-2, IL-4, IL-7, IL-9, and IL-15. Jak3- and gamma c-deficient mice have pleiotropic defects that can be attributed to their inability to respond to multiple specific cytokines. A great deal of recent work has focused on the T cell defects in these mutant mice. Specifically, Jak3- and gamma c-deficient mice have small thymuses revealing a defect in T cell development, and in addition, have functionally unresponsive peripheral T cells with an activated/memory cell phenotype. The thymic defect in these mutant mice strongly resembles that seen in IL-7 and IL-7 receptor knockout mice, suggesting that the lack of IL-7 receptor signaling accounts for this defect in Jak3-/- and gamma c- mice. To characterize this defect further, we have examined the earliest stages of T cell development in adult and fetal Jak3-/- thymuses. These studies identify two discrete developmental defects at the CD4-CD8- stage of T cell maturation. Analyses of peripheral T cells in Jak3-/- and gamma c- mice have also revealed a number of abnormalities. All of the T cells in these mutant mice have an activated phenotype and a large fraction of them are proliferating in vivo. In addition, Jak3-/- and gamma c- T cells are more prone to undergo apoptosis than wild-type T cells. Together, these features account for the decreased IL-2 secretion by in vitro-stimulated Jak3-/- T cells. Overall, many of the lymphoid defects of Jak3- and gamma c-deficient mice can be accounted for by the lack of IL-7R and IL-2R signaling; however, other cytokine systems must also be involved in maintaining peripheral T cell homeostasis.

Bronchocentric mycosis occurring in transplant recipients.

Although a variety of long-term, probably immunologically induced pulmonary changes have been described in recipients of both combined heart-lung and bone marrow transplantation, pulmonary infections continue to remain causes of significant morbidity and mortality as well. Herein we describe three patients (two heart-lung and one bone marrow transplant recipient) who had bronchocentric granulomatous mycosis, a tissue manifestation of fungal infection not previously described in the setting of a transplant host. Although one patient was being treated successfully with antifungal agents for his mucormycosis, two other patients eventually died of invasive aspergillosis. This emphasizes that although this process is histologically somewhat similar to bronchocentric granulomatosis, a high index of suspicion for infection needs to be maintained when this pathologic process is identified in a transplant host.

Effect of spinal construct stiffness on early fusion mass incorporation. Experimental study.

The relationship between initial spinal construct stiffness and the stiffness of the resulting fusion mass was studied by performing standardized 10-segment posterior spinal fusions in goats. Animals were divided into 5 groups based on type of spinal construct, using rods of different diameters (3.2 mm, 4.8 mm, 6.4 mm) with or without rigid crosslinking to produce constructs of different stiffnesses. Stiffness data on 28 animals were obtained by removing the spines en bloc, at 6 or 12 weeks postoperatively, and performing load-deformation testing in axial and torsional loading to determine the stiffness of the fusion masses (rods removed). The initial construct stiffnesses were also compared by ex vivo testing on spine specimens to correlate initial construct stiffness with eventual fusion mass stiffness. In axial testing, results showed stiffer fusion masses from larger diameter rod constructs compared with smaller rod constructs. This was similar to results of control testing on spine specimens ex vivo. Rigid crosslinking did not produce stiffer fusions in axial testing, due to a technical limitation of the button-wire implants used to segmentally fix the rods at each vertebra. In torsional testing, stiffer fusion masses resulted from using larger rods, and rigid Crosslinking also produced the stiffest fusion masses, which was consistent with ex vivo testing. In general, larger diameter (stiffer) rods produced stiffer fusion masses, and no evidence of stress shielding was found.

Targeting nuclear factor-kappa B to overcome resistance to chemotherapy.

Intrinsic or acquired resistance to chemotherapeutic agents is a common phenomenon and a major challenge in the treatment of cancer patients. Chemoresistance is defined by a complex network of factors including multi-drug resistance proteins, reduced cellular uptake of the drug, enhanced DNA repair, intracellular drug inactivation, and evasion of apoptosis. Pre-clinical models have demonstrated that many chemotherapy drugs, such as platinum-based agents, antracyclines, and taxanes, promote the activation of the NF-κB pathway. NF-κB is a key transcription factor, playing a role in the development and progression of cancer and chemoresistance through the activation of a multitude of mediators including anti-apoptotic genes. Consequently, NF-κB has emerged as a promising anti-cancer target. Here, we describe the role of NF-κB in cancer and in the development of resistance, particularly cisplatin. Additionally, the potential benefits and disadvantages of targeting NF-κB signaling by pharmacological intervention will be addressed.

Analysis of low zone tolerance induction in normal and B cell-deficient mice.

To investigate the role of B cells as APCs in acquired tolerance induced by low dose soluble protein Ags, normal and B cell-deficient adult mice were injected i.v. with repeated low doses (10 microgram) of deaggregated OVA, then challenged with OVA in CFA. In animals treated with deaggregated OVA, the in vitro proliferative responses of lymph node T cells to OVA were significantly reduced, and production of the Th1 cytokine, IFN-gamma, in response to OVA was reduced to undetectable levels. This occurred in both normal and B cell-deficient treated animals. B cells were also unnecessary for self tolerance of T cells to the transgenic self Ag, hen egg lysozyme, in a strain with a very low serum lysozyme concentration. Partial low zone tolerance induced by deaggregated, low dose OVA was selective for T cell responses as measured by in vitro proliferation and IL-2 and IFN-gamma production, because Ab responses of B cell-sufficient mice to this T cell-dependent Ag were largely unaffected. Both treated and untreated animals produced equivalent titers of anti-OVA Abs, predominantly of the IgG1 and IgG2b isotypes, following challenge with OVA in CFA.

A profound deficiency in thymic progenitor cells in mice lacking Jak3.

Humans and mice with genetic deficiencies that lead to loss of signaling through common gamma-chain (gammac)-containing cytokine receptors have severe defects in B and T lymphocytes. In humans, these deficiencies lead to a complete absence of T cells, whereas in mice, small thymuses give rise to normal numbers of peripheral T cells. We have examined the first wave of developing T cells in Jak3-/-, IL-7-/-, and IL-7Ralpha-/- fetal mice, and have found a near absence of thymic progenitor cells. This deficiency is highlighted by the complete inability of Jak3-/- progenitor cells to reconstitute T cell development in the presence of competing wild-type cells. These data clearly demonstrate a strong common basis for the T cell deficiencies in mice and humans lacking gammac/Jak3 signaling pathways.

The ultrasound diagnosis of hydatidiform mole.

Experience with ultrasound compound 'B' scanning in 18 cases of hydatidiform mole is presented. The scan appearances are analysed with respect to the presence or absence of transonic areas, and to the uniformity of echogenicity elsewhere in the uterus. The differential diagnosis is discussed. The commonest appearance seen in a hydatidiform mole is the combination of multiple small transonic areas with uneven echogenicity in the remainder of the uterine cavity. The condition most likely to cause diagnostic confusion is early normal pregnancy with a bulky decidua, but incomplete abortion and uterine fibroid may also be confused with hydatidiform mole.

Adrenal medullary tumors and iris proliferation in a transgenic mouse model of neurofibromatosis.

The expression of the human T-cell lymphotropic virus type 1 (HTLV-1) tax gene in transgenic mice has been shown to result in the development of neurofibromas. Further characterization of these transgenic mice has revealed other significant pathologic similarities between this transgenic mouse model and human neurofibromatosis (NF). Pheochromocytomas of the adrenal medulla and hamartomas of the iris are well-recognized manifestations of human NF. Adrenal medullary tumors have been found in 68% of transgenic animals that were studied. They appear, however, not to be pheochromocytomas, but rather composed of undifferentiated spindle cells. Proliferation of fibroblastlike cells in the iris also occurs in one-half of the transgenic animals surviving more than 6 months. Melanocytes, however, have not been found in the transgenic iris lesion, although they are characteristically found in the Lisch nodules of human NF. The similarities between human neurofibromatosis and this transgenic mouse model (in which the overexpression of a single gene results in neoplasia) are discussed. This transgenic system may provide further insights into molecular mechanisms involved in the pathogenesis of neurofibromatosis.

A monoclonal antibody reactive with a 40-kDa molecule on fetal thymocytes and tumor cells blocks proliferation and stimulates aggregation and apoptosis.

E710.2.3 is a murine thymic lymphoma cell line with an immature phenotype (CD4-CD8-) that proliferates in response to thymocytes or PMA when cultured at low density and proliferates spontaneously when grown at high density. To identify functional molecules on this cell line, we screened for mAbs that could block its proliferation. A hamster mAb, DMF10.62.3, inhibited the spontaneous, thymocyte-induced, and PMA-stimulated proliferation of E710.2.3 in vitro and induced these cells to undergo apoptosis. The mAb also caused homotypic aggregation of E710.2.3, which was inhibited by cytochalasin B, trifluoperazine, a combination of sodium azide and 2-deoxyglucose, EDTA, incubation at 4 degrees C, or treatment with paraformaldehyde. The DMF10 62.3 mAb stained a number of immortalized murine and human cell lines and, where tested, blocked their proliferation and caused death to varying extents by apoptosis. The molecule recognized by the mAb DMF10.62.3 was expressed on day 14 fetal thymus Thy1.2-positive cells. However, it was not detected on adult murine thymocytes, splenocytes, or bone marrow cells or on splenic LPS-activated B cells or Con A-activated T cells. The Ab immunoprecipitated a 40-kDa molecule from E710.2.3 that was not glycosylphosphatidylinositol linked. The data suggest that the molecule recognized by DMF62.3 is a novel cell surface molecule that may be involved in cell proliferation and/or cell death.