Quinolone use as a risk factor for nosocomial Clostridium difficile-associated diarrhea

OBJECTIVE

To determine modifiable risk factors for nosocomial Clostridium difficile-associated diarrhea (CDAD).

DESIGN

Case-control study.

SETTING

300-bed tertiary-care hospital.

PARTICIPANTS

Hospital inpatients present during the 3-month study period.

METHODS

Case-patients identified with nosocomial CDAD over the study period were compared to two sets of control patients: inpatients matched by age, gender, and date of admission; and inpatients matched by duration of hospital stay. Variables including demographic data, comorbid illnesses, antibiotic exposure, and use of gastrointestinal medications were assessed for case- and control-patients. Conditional logistic regression was performed to identify risk factors for nosocomial CDAD.

RESULTS

27 case-patients were identified and were compared to the two sets of controls (1:1 match for each comparison set). For the first set of controls, use of ciprofloxacin (odds ratio [OR], 5.5; 95% confidence interval [CI 95], 1.2-24.8; P=.03) was the only variable that remained significant in the multivariable model. For the second set of controls, prior exposure to cephalosporins (OR, 6.7; CI 95, 1.3-33.7; P=.02) and to ciprofloxacin (OR, 9.5; CI 95, 1.01-88.4; P=.05) were kept in the final model.

CONCLUSIONS

Along with cephalosporins, prior quinolone use predisposed hospitalized patients to nosocomial CDAD. Quinolones should be used judiciously in acute-care hospitals, particularly in those where CDAD is endemic.

Assessment of changes in tumor heterogeneity following neoadjuvant chemotherapy in primary esophageal cancer

To assess the changes in computed tomography (CT) tumor heterogeneity following neoadjuvant chemotherapy in esophageal cancer. Thirty-one consecutive patients who received neoadjuvant chemotherapy for esophageal cancer were identified. Analysis of primary tumor heterogeneity (texture) was performed on staging and post-chemotherapy CT scans. Image texture parameters (mean grey-level intensity, entropy, uniformity, kurtosis, skewness, standard deviation of histogram) were derived for different levels of image filtration (0-2.5). Proportional changes in each parameter following treatment were obtained. Comparison between pathological tumor response and texture parameters was analyzed using Mann-Whitney U-test. The relationship between CT texture and overall survival) was estimated using the Kaplan-Meier method. Tumor texture became more homogeneous after treatment with a significant decrease in entropy and increase in uniformity (filter 1.0 and 2.5). Pretreatment (filter 1.5, P = 0.006) and posttreatment standard deviation of histogram (filter 1.0, P = 0.009) showed a borderline association with pathological tumor response. A proportional change in skewness <0.39 (filter 1.0) was associated with improved survival (median overall survival 36.1 vs. 11.1 months; P < 0.001). CT tumor heterogeneity decreased following neoadjuvant chemotherapy and has the potential to provide additional information in primary esophageal cancer.

A functional assessment of insulin/insulin-like growth factor-I hybrid receptors

Insulin/insulin-like growth factor-I (IGF-I) hybrid receptors are composed of an alpha beta-heterodimer from an insulin receptor and an alpha beta-heterodimer from an IGF-I receptor. In this study, we evaluate the effect of insulin receptor overexpression on hybrid formation. The more human insulin receptors expressed in rodent fibroblasts, the greater the percentage of endogenous rat IGF-I receptors that form hybrid receptors. The IGF-I receptor in rodent fibroblasts has two receptor isoforms, one with a 95-kilodalton (kDa) beta-subunit and one with an 105 kDa beta-subunit. A truncated mutant insulin receptor was used to demonstrate that only activated IGF-I receptors with the 105-kDa beta-subunit form hybrid receptors with the insulin receptor. Insulin/IGF-I hybrid receptors with a kinase-defective insulin heterodimer undergo trans and a small amount of cis autophosphorylation, but overall autophosphorylation is markedly decreased from that seen in hybrids with a kinase-competent insulin receptor. The kinase-defective insulin receptor heterodimer functions as a dominant-negative, inhibiting phosphorylation by the kinase-competent IGF-I receptor heterodimer. The kinase-defective hybrid receptors are, however, able to undergo internalization. Despite an increasing percentage of insulin/IGF-I hybrid receptors in the three cell lines studied, the rates of IGF-I internalization and degradation remain similar to those mediated by the IGF-I receptor and distinct from those of insulin receptor heterotetramers. In conclusion, IGF-I-stimulated insulin/IGF-I hybrid receptors function like IGF-I receptors, rather than like insulin receptors.

A yeast gene essential for regulation of spindle pole duplication

In eucaryotic cells, duplication of spindle poles must be coordinated with other cell cycle functions. We report here the identification in Saccharomyces cerevisiae of a temperature-sensitive lethal mutation, esp1, that deregulates spindle pole duplication. Mutant cells transferred to the nonpermissive temperature became unable to continue DNA synthesis and cell division but displayed repeated duplication of their spindle pole bodies. Although entry into this state after transient challenge by the nonpermissive temperature was largely lethal, rare survivors were recovered and found to have become increased in ploidy. If the mutant cells were held in G0 or G1 during exposure to the elevated temperature, they remained viable and maintained normal numbers of spindle poles. These results suggest dual regulation of spindle pole duplication, including a mechanism that promotes duplication as cells enter the division cycle and a negative regulatory mechanism, controlled by ESP1, that limits duplication to a single occurrence in each cell division cycle. Tetrad analysis has revealed that ESP1 resides at a previously undescribed locus on the right arm of chromosome VII.

Intramolecular 1,3-dipolar cycloadditions of norbornadiene-tethered nitrile oxides

Efficient routes to the synthesis of norbornadiene-tethered nitrile oxides have been developed, and their intramolecular 1,3-dipolar cycloadditions were studied. The cycloadditions occurred in good yields for a variety of substrates and were found to be highly regio- and stereoselective, giving single regio- and stereoisomers in most cases.

Highly Regio- and Stereoselective Intramolecular 1,3-Dipolar Cycloadditions of Norbornadiene-Tethered Nitrile Oxides

[reaction: see text] Intramolecular cycloadditions with high regio- and stereocontrol are important methods for the efficient assembly of complex molecular structures. Efficient routes to the synthesis of norbornadiene-tethered nitrile oxides have been developed, and their intramolecular 1,3-dipolar cycloadditions were studied. The cycloadditions occurred in good yields for a variety of substrates and were found to be highly regio- and stereoselective.

Characterization of two epitopes on insulin using monoclonal antibodies

Three monoclonal antibodies (MAb), 21 (IgG1), I10 (IgG1) and H38 (IgG2b), to insulin have been tested for cross-reactivity with 11 species variants of insulin and three of proinsulin. Correlations of differences of reactivities between the MAb and the species variants of insulin with the respective amino acid sequences of the latter have permitted the identification of two epitopes recognized by the MAb which encompass the regions in the A- and B-chains of insulin subject to frequent evolutionary amino acid substitutions. MAb 21 and H38 are directed to an epitope which includes residues B27-30 and A1 or A4 and can discriminate between human and pig insulins which differ only at B30. MAb 21 reacts with human (B30 thr) but not with pig (B30 ala) insulins, whereas MAb H38 exhibits a reciprocal specificity. Neither MAb 21 nor MAb H38 react with human or pig proinsulins respectively indicating that the presence of the C-peptide joining A1 to B30 masks the epitope. MAb 21 reacts with human insulin 125I-labeled at tyr A14 but not B26 suggesting that incorporation of the I atom at B26 also masks the epitope. MAb I10 is directed to an epitope which includes A8-10 and A4 or B3 with a specificity for the human A8-10 sequence. MAb I10 reacts with human proinsulin and human insulin 125I-labeled at either tyr A14 or B26.

Y-1 adrenocortical tumor cells contain atrial natriuretic peptide receptors which regulate cyclic nucleotide metabolism and steroidogenesis

The effects of atrial natriuretic peptide (ANP) on adrenocortical fasciculata cells were examined in the ACTH-responsive Y-1 mouse adrenocortical tumor cell line. Y-1 cell membranes rapidly bound [125I]ANP, with equilibrium binding (22 C) reached within 45 min. Binding of [125I]ANP was inhibited in a concentration-dependent manner by unlabeled ANP and atriopeptin-I (IC50, approximately 1.2 X 10(-9) and 1.6 X 10(-8) M, respectively), but not by C- or N-terminal-deleted ANP fragments, ACTH, or arginine vasopressin (up to 10(-6) M). Scatchard analysis revealed a single class of high affinity binding sites with a Kd of 1.6 X 10(-10) M and a binding capacity of 560 fmol/mg protein. Photo-affinity labeling demonstrated the specific binding of ANP to two protein entities of 130 and 63 kDa. ANP stimulated both cGMP synthesis and secretion from Y-1 cells (EC50, approximately 3.5 X 10(-9) M). Release of the nucleotide was inhibited by probenecid (IC50, approximately 5 X 10(-5) M). The atrial peptide partially inhibited ACTH-stimulated cAMP formation (IC50, approximately 10(-8) M) and partially antagonized basal and ACTH-stimulated steroidogenesis. The data demonstrate the presence in Y-1 cells of specific and saturable ANP receptors, activation of which leads to changes in cyclic nucleotide metabolism and inhibition of steroidogenesis.

Becker expander implants: truly a long term single stage reconstruction?

Despite being more expensive than conventional tissue expanders, Becker expanders offer the advantage of single stage breast reconstruction. However, the large series in published literature which report good outcomes of Becker expanders in breast reconstruction have a mean follow up period of less than three years. This does not allow for definitive conclusions as to whether the Becker expander truly meets its design goal of a lasting single stage breast reconstruction. This study is a retrospective case note review of all patients who underwent breast reconstruction using a Becker expander at our unit from 1993 to 1998, with a mean follow up of 12.5 years. Sixty-eight Becker-only breast reconstructions were carried out following oncological and risk-reducing mastectomies, and for congenital hypoplasias. There was a high premature overall explantation rate with 68% of expanders removed by 5 years due to complications which included poor aesthetics, capsular contracture and infection. The mean time to explantation for these patients was only 23 months, and time to 50% overall expander removal ('half life') was just 30 months. On subgroup analysis, patients in the congenital hypoplasias group had a significantly better rate of expander retention with 67% remaining in situ at 10 years. In comparison, patients in the oncological and risk-reducing mastectomy groups had implant retention rates of 2% and 7% respectively. The Becker expander does not appear to meet its design purpose of lasting single stage breast reconstruction in post-mastectomy cases. In contrast, it appears to have significantly better longevity when used for congenital hypoplasias.

Production and secretion of porcine urokinase in Saccharomyces cerevisiae: characterization of the secreted gene product

The properties of porcine urokinase plasminogen activator (u-PA), produced and secreted by Saccharomyces cerevisiae, were studied to evaluate processing of the enzyme by yeast. Porcine u-PA cDNA was positioned behind the triosephosphate isomerase promoter and the yeast alpha-mating factor secretion signal sequences in a yeast expression vector, pZV125. Greater than 99% of the secreted PA activity was found to be single chain (pro-urokinase). The secreted gene product could be converted to two-chain (tc) with plasmin and then purified to homogeneity on benzamidine sepharose. Plasmin cleavage resulted in the formation of high Mr (HMW) and low Mr moieties representing HMW tc and free catalytic domain, respectively, as detected by N-terminal amino acid sequence analysis. Approximately 60-70% of the secreted activity was found to be associated with hyperglycosylated fractions from G-75 sizing columns. Approximately 30% of the total activity was secreted into the culture medium, where levels of activity approached 200 I.U./ml.

Synthesis of albumin and malic enzyme in wheat-germ lysates and Xenopus laevis oocytes programmed with chicken-liver messenger RNA

Undegraded, biologically-active, polyadenylated RNA was isolated from chicken liver by a rapid, simple procedure. Liver cells were dispersed mechanically and then broken gently by controlled Dounce homogenization in the absence of detergent or ribonuclease inhibitors. After removing lysosomes and mitochondria by centrifugation, RNA was precipitated at pH 5.2. Polyadenylated mRNA was isolated directly from the detergent-solubilized precipitate by oligo(dT)-cellulose chromatography. The resulting RNA was translated into liver-specific peptides in both the wheat germ lysate and Xenopus laevis oocytes. Translatable albumin mRNA was detected in the liver cytoplasm of both fed 3-week-old chicks and unfed, day-old chicks. Translatable malic enzyme mRNA was only detected in the livers from the fed chicks.

Co-registration of cone beam CT and planning CT in head and neck IMRT dose estimation: a feasible adaptive radiotherapy strategy

OBJECTIVE

To investigate if cone beam CT (CBCT) can be used to estimate the delivered dose in head and neck intensity-modulated radiotherapy (IMRT).

METHODS

15 patients (10 without replan and 5 with replan) were identified retrospectively. Weekly CBCT was co-registered with original planning CT. Original high-dose clinical target volume (CTV1), low-dose CTV (CTV2), brainstem, spinal cord, parotids and external body contours were copied to each CBCT and modified to account for anatomical changes. Corresponding planning target volumes (PTVs) and planning organ-at-risk volumes were created. The original plan was applied and calculated using modified per-treatment volumes on the original CT. Percentage volumetric, cumulative (planned dose delivered prior to CBCT + adaptive dose delivered after CBCT) and actual delivered (summation of weekly adaptive doses) dosimetric differences between each per-treatment and original plan were calculated.

RESULTS

There was greater volumetric change in the parotids with an average weekly difference of between -4.1% and -27.0% compared with the CTVs/PTVs (-1.8% to -5.0%). The average weekly cumulative dosimetric differences were as follows: CTV/PTV (range, -3.0% to 2.2%), ipsilateral parotid volume receiving ≥26 Gy (V26) (range, 0.5-3.2%) and contralateral V26 (range, 1.9-6.3%). In patients who required replan, the average volumetric reductions were greater: CTV1 (-2.5%), CTV2 (-6.9%), PTV1 (-4.7%), PTV2 (-11.5%), ipsilateral (-10.4%) and contralateral parotids (-12.1%), but did not result in significant dosimetric changes.

CONCLUSION

The dosimetric changes during head and neck simultaneous integrated boost IMRT do not necessitate adaptive radiotherapy in most patients.

ADVANCES IN KNOWLEDGE

Our study shows that CBCT could be used for dose estimation during head and neck IMRT.

Pedestrian Fatalities Associated With Halloween in the United States

This study examines 42 years of National Highway Traffic Safety Administration data to establish whether Halloween is associated with an increased rate of pedestrian fatalities.

Basal and stimulated ANF secretion: role of tissue preparation

Our previous results showed that addition of agonists, such as vasopressin and angiotensin, added to incubation medium with freshly excised rat atria caused marked release of atrial natriuretic factor (ANF). This release was in the form of prohormone rather than active peptide. Since others had difficulty reproducing these findings, in the present study we investigated ANF release with and without angiotensin addition in two sets of atrial tissue. In the first, tissue was blotted and carefully cleaned as previously described; in the second, atrial tissue was placed into incubation medium without prior preparation. ANF activity in the medium was measured by radioimmunoassay and receptor assay. Using the immunoassay, basal release of ANF was threefold greater from prepared vs. nonprepared atrial tissue; significant stimulation by angiotensin was seen only in the prepared atria. ANF release measured by radioreceptor assay was 1/5-1/10 of that measured by immunoassay. Taking the difference between the two measurements as an index of prohormone secretion, the results confirm that both basal and stimulated release was primarily in the form of proANF. Scanning electron microscopy revealed that cleaning of the atria had removed the endocardial lining of the tissue. The results thus indicate that an intact endocardium can prevent agonist-induced proANF secretion, suggesting that this tissue may be an important modulator of plasma ANF levels.

Drug governs the morphology of polyalkylated block copolymer aggregates

Polyalkylated copolymers based on mPEG-b-(AGE-C_{6,12 or 18})₂₅ have been used to formulate clinically relevant concentrations of doxorubicin (DOX) and the impact of drug incorporation on copolymer aggregation behaviour was examined. The copolymer aggregates were analyzed by various microscopy techniques (TEM, cryo-TEM and AFM) and scattering methods (SANS, DLS). In the absence of the drug, the copolymers formed largely non-spherical aggregates (i.e. cylinders, vesicles). Drug incorporation during copolymer aggregate formation directed the formation of only spherical aggregates. As well, the nature of the core-forming block was found to influence drug release and cytotoxicity of the formulations.

In vitro secretion of atrial natriuretic factor: receptor-mediated release of prohormone

Secretion of atrial natriuretic factor (ANF) in vivo is thought to be mediated by atrial distension. We have shown previously that nonstretched atria can release natriuretic activity in vitro when stimulated by certain agonists. In the present study atrial appendages from freshly excised rat hearts were incubated at 37 degrees C for up to 1 h in the presence of either vasopressin (5 X 10(-9) mol/l) or angiotensin II (2.5 X 10(-7) mol/l). Aliquots of postincubation media were injected intravenously into anesthetized bioassay rats to determine natriuretic activity. Control media, in which atria had been incubated without agonist, did not cause natriuresis. Significant increases in sodium excretion were seen after injection of media in which atria had been incubated in the presence of either agonist. Injection of medium with the same agonist concentration did not result in comparable natriuresis. Radioimmunoassay (RIA) indicated a high concentration of immunoactive ANF in the natriuretic media. However, radioreceptor assay (RRA) of the same media gave apparent ANF concentrations that were lower by about three orders of magnitude. Because the antibody used in the RIA cross reacts with ANF prohormone, whereas the RRA is sensitive only to the active form, we concluded that agonist-induced, stretch-independent release of ANF is in the form of prohormone, which can be converted to the active hormone in the circulation of the bioassay animal. The conclusion of prohormone release was confirmed by liquid chromatography. The data thus suggest that receptor-mediated as well as stretch-induced ANF secretion may be important in regulating the activity of the ANF system.

A large-scale multi-center independent validation study of a panel of seven biomarkers for the detection of ovarian cancer

5057

Background: Previously we discovered seven serum biomarkers: ITIH4, transthyretin, ApoA1, CTAPIII, hepcidin, transferrin, and SAA, for the detection of ovarian cancer. They are fragments, cleavages, or PTMs of circulating proteins that are difficult to measure by conventional immunoassays. Using optimzed mass spectrometry assays, we evaluated these biomarkers in a large-scale multi-center study. Methods: A total of 607 serum samples from five sites were analyzed using SELDI TOF-MS protocols optimized for the seven biomarkers. They included 234 women with benign gynecologic diseases, and 373 patients with invasive epithelial ovarian cancer (101 early stage, 231 late stage, and 40 stage unknown). Among them, 165 benigns and 228 cancers had a CA125 available at time of analysis. The median and quartiles of CA125 for benign, early stage, and late or unknown stage were 26/11/57 IU, 80/22/434 IU, and 234/40/1114 IU, respectively. The biomarkers were assessed individually using the Mann-Whitney U Test. A linear composite index was derived in an unsupervised fashion using data from one site and then calculated for the remaining data using the fixed formula. ROC curve analyses were performed on data from individual sites and all sites combined. Results: All seven biomarkers individually demonstrated statistically significant differentiating power, and the majority had p-value<0.00001. AUCs of the composite index in ROC analyses for the six sites were 0.602, 0.566, 0.821, 0.813, and 0.592 in detecting cancer at all stages from benign. On the combined data, the differences in AUC between the index and CA125 were not statistically significant for the detection of cancer at all stages (AUC=0.706 vs. 0.725) or early stages only (AUC=0.534 vs. 0.653). However, the index did better at the high-sensitivity range. At a fixed sensitivity of 86%, the specificity of the index was 34% (77/226) compared to CA125 at 26% (42/163). For early stage cases, at a fixed sensitivity of 84%, the specificity of the index was 24% (55/226) compared to CA125 at 14%% (22/163). Conclusions: We validated seven previously discovered biomarkers, individually and in combination. Prospective studies and assay development are under way to further characterize their clinical utility.

[Table: see text]