Interim estimates of 2013/14 influenza clinical severity and vaccine effectiveness in the prevention of laboratory-confirmed influenza-related hospitalisation, Canada, February 2014.

During the 2013/14 influenza season in Canada, 631 of 654 hospitalisations for laboratory-confirmed influenza enrolled in sentinel hospitals were due to Influenza A. Of the 375 with known subtype, influenza A(H1N1) accounted for 357. Interim unmatched vaccine effectiveness adjusted for age and presence of one or more medical comorbidities was determined by test-negative case-control design to be 58.5% (90% confidence interval (CI): 43.9-69.3%) overall and 57.9% (90% CI: 37.7-71.5) for confirmed influenza A(H1N1).

Effects of arachidonic acid metabolites in a murine model of squamous cell carcinoma.

BACKGROUND: A murine model (C3H mice) of squamous cell carcinoma (SCCVII) has been used to investigate the role of arachidonic acid (AA) metabolites in head and neck cancer. Inhibition of tumor growth by cyclooxygenase (COX) and lipoxygenase (LOX) inhibitors of AA metabolism has been associated with changes in levels of AA metabolites in tumor tissues and inflammatory cell infiltrates. To characterize this model further, the effects of exogenous AA metabolites on tumor growth in vitro and in vivo were investigated. METHODS: Following subcutaneous inoculation with SCCVII tumor cells, control (16 mice) and treatment (24 mice) groups were injected with peritumoral vehicle or AA metabolite. Peritumoral injections of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and 12-hydroxyeicosatetraenoic acid (12-HETE) were performed for 16-21 days, and final excised tumor weights were measured. In vitro production of PGE2 and LTB4 was assayed in 2-5 day cultures of SCCVII. Exogenous PGE2 effects on tumor cell growth was assessed with the MTT assay in vitro. RESULTS: Tumor growth was significantly inhibited (p =.03) following peritumoral injection of PGE2. Final tumor weights were not affected by LTB4 or 12-HETE. Tumor inhibition by PGE2 was associated with increased tumor tissue levels of LTB4 (p =.04). In vitro, SCCVII produced minimal amounts of PGE2 and LTB4, and PGE2 had minimal effect on growth. CONCLUSIONS: In this model, tumor inhibition by exogenous PGE2 is primarily mediated by affecting host-tumor interactions, although there may be some direct effect on tumor cells. Changes in tumor tissue levels of LTB4 following peritumoral PGE2 administration may be attributable to negative feedback inhibition of the COX pathway with shunting into the LOX pathway. SCCVII cells are probably not a significant source of prostaglandins and leukotrienes in vivo. These data provide insight into the mechanism of action of inhibitors of AA metabolism on tumor growth.

Mycobacteriocidal action of exogenous nitric oxide.

We tested the hypothesis that exposure of extracellular Mycobacterium tuberculosis to low concentrations (< 100 ppm) of nitric oxide (NO) for short periods (24 h or less) will result in microbial killing. We observed that NO had both dose- and time-dependent cidal effects that were very significant by two-way analysis of variance (F ratios of 13.4 [P < 0.001] and 98.1 [P < 0.0001], respectively). Conceivably, extracellular bacilli in patients with pulmonary tuberculosis might be vulnerable to exogenous NO.

Potentiation of cisplatin antitumor activity using a vitamin D analogue in a murine squamous cell carcinoma model system.

In a murine squamous cell carcinoma (SCC) model, we have demonstrated that both 1,25-dihydroxycholecalciferol (1,25-D3) and the analogue 1,25-dihydroxy-16-ene-23-yne-cholecalciferol (Ro23-7553) have significant in vitro and in vivo antitumor activity. We have examined here the cell cycle effect of 1,25-D3 and Ro23-7553 on SCCVII/SF tumor cells by quantitating nuclear DNA using a detergent-trypsin method via flow cytometry analysis. Both 1,25-D3 and Ro23-7553 resulted in a significant increase of cells in G0-G1, with an accompanying decrease of cells in S phase. The ability to arrest cells in G0-G1 has been exploited by combining Ro23-7553 with the cytotoxic agent cisplatin (cis-diamminodichloroplatinum; cDDP). Using the in vitro clonogenic assay, pretreatment with Ro23-7553 for 24-48 h significantly enhanced cDDP-mediated tumor cell kill as compared to concurrent treatment with Ro23-7553 and cDDP or cDDP alone. To examine the effect of Ro23-7553 and cDDP in vivo, C3H/HeJ mice with 9-14-day SCC tumors were treated either for 3 days with varying i.p. doses of Ro23-7553 or for 7 days continuously through the use of Alzet pumps, and on the last day of Ro23-7553 treatment, cDDP (1-6 mg/kg) was administered. Using the in vivo excision tumor cell clonogenic assay, in which tumors were removed from animals 24 h after cDDP treatment and plated in a clonogenic assay, pretreatment with Ro23-7553 markedly enhanced cDDP-mediated clonogenic tumor cell kill, even at low doses of cDDP as compared to cDDP treatment alone. Similarly, a significant decrease in fractional tumor volume and increase in tumor regrowth delay was observed when animals were pretreated before cDDP with Ro23-7553 as compared to either agent alone. These results demonstrate a significant enhanced antitumor effect with Ro23-7553 pretreatment before cDDP both in vitro and in vivo and suggest that Ro23-7553 may potentiate cDDP cytotoxicity through effects on cell cycle progression.

Vitamin D inhibition of prostate adenocarcinoma growth and metastasis in the Dunning rat prostate model system.

OBJECTIVES: Risk factors for prostate cancer (PCa)-related mortality include old age, black race, and residence in northern latitudes. The objectives of this study are to examine the in vitro and in vivo effects of 1,25-dihydroxycholecalciferol (1,25-D3) and less-hypercalcemic analogues on the Dunning rat prostate adenocarcinoma model. METHODS: To evaluate the effect of 1,25-D3 on PCa in vitro, we used the highly metastatic Mat-lylu (MLL) and moderately metastatic R3327-AT-2 (AT-2) Dunning prostate cell lines, and examined effects on growth, clonogenicity, differentiation, and cell cycle. In vivo analysis included examination of the effects of these compounds on tumor growth and metastasis. RESULTS: Using both the 3-day MTT and 7-day clonogenic assay, 1,25-D3 demonstrated a growth inhibitory effect with a concentration for 50% inhibition (IC50) of approximately 20 microM for both MLL and AT-2. Cell cycle analysis of treated MLL cells (10 microM 1,25-D3 for 48 hours) had 25% more cells in the G0/G1 phase than did control cells. To examine the in vivo effect of 1,25-D3 and the less hypercalcemic vitamin D analogue, Ro25-6760 (or 6760), on MLL PCa growth and metastasis, tumors (5 x 10(5) cells) were implanted subcutaneously into the flank of Copenhagen rats on the same day that treatment was initiated with 1,25-D3 (1 microgram) or 6760 (1 or 5 micrograms); rats received treatment three times a week. After 3 weeks, 1,25-D3 and 6760 (5 micrograms dosing) resulted in an inhibition of tumor volume and a reduction in the number and size of lung metastases. CONCLUSIONS: These preclinical studies demonstrate the profound in vitro, or in vivo, or both antiproliferative and differentiating effects of 1,25-D3 and 6760 on PCa and suggest that these drugs may have potential beneficial effects in the treatment of advanced PCa.

Refractive-index measurements in freezing sea-ice and sodium chloride brines.

Sea ice contains numerous pockets of brine and precipitated salts whose size and number distributions change dramatically with temperature. Theoretical treatment of scattering produced by these inclusions requires information on refractive-index differences among the brine, salts, and surrounding ice. Lacking specific data on refractive-index variations in the brine, we carried out laboratory measurements in freezing-equilibrium solutions between -2 and -32 °C. Index values at 589 nm increased from 1.341 to 1.397 over this temperature range, corresponding to salinities of 35 and 240 parts per thousand (ppt). Spectral data were also taken at 50-nm intervals between 400 and 700 nm in nonequilibrium solutions with salinities ranging up to 300 ppt. Spectral gradients increased slightly with salinity but showed no measurable dependence on temperature between +12 and -16 °C. The Lorentz-Lorenz equation, combined with data on density, molar refractivities, and brine composition, yielded temperature-dependent index predictions in excellent agreement with the experimental data. Similar index and density measurements in freezing sodium chloride brines yielded values nearly identical to those in the sea-ice brines. The absence of mirabilite crystals in sodium chloride ice, however, will cause it to have higher transmissivity and lower reflectivity than sea ice above -22 °C.

In vitro sensitivity of human hematopoietic progenitor cells to 4-hydroperoxycyclophosphamide.

Protracted engraftment and prolonged thrombocytopenia remain problems when marrow purged with 4-hydroperoxy-cyclophosphamide (4-HC) is employed for autotransplants. Toxic effects of 4-HC on early progenitor and stem cells might play an important causative role. Surprisingly, few investigations have examined the effects of 4-HC on progenitor cells other than colony-forming units-granulocyte/macrophage (CFU-GM) and burst-forming units-erythroid (BFU-E), and only one study could be found where 4-HC exposure was carried out on cells purified beyond the buffy coat stage. Since the cellular milieu, and in particular the red blood cell count, can ameliorate 4-HC toxicity, the suppressive effect of this agent on marrow stem cells might be underestimated. We therefore investigated the relative 4-HC sensitivity of different human bone marrow progenitor cells in vitro using partially purified adherent cell- and T lymphocyte-depleted bone marrow mononuclear cells (A-T-MNC). Cells were exposed to increasing doses (10 to 200 micrograms/mL) of 4-HC using a standard purging protocol established for bone marrow buffy coat cells. Effects on mixed (CFU-Mix), erythroid (CFU-E and BFU-E), granulocyte-macrophage (CFU-GM), and stromal cell (CFU-F) progenitors were determined. In addition, we examined the 4-HC sensitivity of megakaryocyte progenitors (CFU-Meg) since, to our knowledge, this has not been reported before. As expected, increasing doses of 4-HC led to progressive inhibition of hematopoietic colony formation. CFU-F, CFU-Mix, and CFU-Meg appeared most resistant to 4-HC exposure, while CFU-E, BFU-E, and CFU-GM appeared most sensitive. At doses over 100 micrograms/mL, the usual concentration recommended for purging of buffy coat cells, hematopoietic colony formation was completely inhibited. These data suggest that if more highly purified marrow cells are employed for purging, lower 4-HC doses may need to be used. They also suggest that the thrombocytopenia that frequently accompanies 4-HC purging is not likely due to loss of CFU-Meg.

Differential DNA sequence deletions from chromosomes 3, 11, 13, and 17 in squamous-cell carcinoma, large-cell carcinoma, and adenocarcinoma of the human lung.

Activation of protooncogenes and inactivation of putative tumor suppressor genes are genetic lesions considered to be important in lung carcinogenesis. Fifty-four cases of non-small-cell lung cancer (23 adenocarcinomas, 23 squamous-cell carcinomas, and 8 large-cell carcinomas) were examined for loss of DNA sequences at 13 polymorphic genetic loci. Loss of heterozygosity was seen more frequently in squamous-cell carcinoma than in adenocarcinoma. The loss of DNA sequences from the short arm of chromosome 17 (D17S1 locus) was detected in 8 of 9 heterozygous cases of squamous-cell carcinoma and in only 2 of 11 heterozygous cases of adenocarcinomas. Furthermore, in 7 of these 8 squamous-cell carcinomas, loss of heterozygosity from chromosome 17 was accompanied by loss of DNA sequences from chromosome 11. The spectrum of allelic sequences lost from chromosome 11 was, however, similar in every type of carcinoma studied, and the data show two regions commonly deleted from chromosome 11 (11pter-p15.5 and 11p13-q13) that may have a role in the pathogenesis of all these types of non-small-cell bronchogenic carcinoma. Loss of DNA sequences from chromosome 3 was seen in 16 of 31 cases where the constitutive DNA was heterozygous-i.e., informative. These data included only 6 of 16 cases where loss of heterozygosity involved a chromosomal locus previously shown to be lost consistently in small-cell lung cancer (DNF15S2). Loss of heterozygosity at the chromosome 13q locus, D13S3, was seen in 9 of 21 informative cases, and in 2 cases, both adenocarcinomas, duplication of the intact DNA sequences suggested the possibility that mitotic recombination had occurred. Frequent DNA sequence deletions, including those from chromosome 17, in squamous-cell carcinomas may reflect the extensive mutagenic and clastogenic effects of tobacco smoke that may lead to inactivation of putative tumor-suppressor genes.

Detection and characterization of human serum antibodies to polycyclic aromatic hydrocarbon diol-epoxide DNA adducts.

The presence of serum antibodies to the diol-epoxide DNA adducts of representative polycyclic aromatic hydrocarbons (PAH), chrysene, benz[a]anthracene and benzo[a]pyrene, was determined by ELISA using serum samples obtained from normal healthy individuals. Antibodies that reacted against PAH adducted-DNA, but not against PAH-adducted protein, were found in the serum of approximately 40% of the test individuals. Specificity analysis of the antibodies demonstrated that serological cross-reactions between the benzo[a]pyrene and the chrysene diol-epoxide adducts were present. Similar cross-reactivity between the benz[a]anthracene and the chrysene adducts was observed. Sera containing antibodies that were apparently specific for each of the three PAH-DNA adducts were also identified. The presence of antibodies to PAH-DNA adducts indicates both past exposure to these carcinogenic PAH and their metabolic activation to the DNA damaging metabolites. These antibodies may prove to be useful in both retrospective and prospective epidemiological studies of various diseases associated with PAH exposure.

The effect of triethylenetetramine dihydrochloride on the in vivo susceptibility of Pseudomonas aeruginosa to gentamicin.

A chelating agent, triethylenetetramine dihydrochloride (TRIEN dihydrochloride) increased the efficacy of gentamicin in vivo against a clinical isolate of P. aeruginosa, designated Ps 15. Mice which were inoculated with 10 X LD50 of Ps 15 and treated with doses of 2 approximately 16 mg of gentamicin per kg per day all died. However, treatment with 8 mg of gentamicin per kg body weight per day plus 30 mg of Trien dihydrochloride per day markedly reduced the mortality. The combined therapy also reduced the number of viable organisms that accumulated in the kidney during a 24-hour period post inoculation. When a dosage level of 8 mg of gentamicin was exceeded in the combined treatment regimen, all of the infected mice died, and a high concentration of endotoxin could be detected in the mouse sera by the limulus assay.

Effect of triethylenetetramine dihydrochloride on the antibiotic susceptibility of Pseudomonas aeruginosa.

A chelating agent, triethylenetetramine dihydrochloride, interacted synergistically in vitro with both gentamicin and carbenicillin against a clinical isolate of Pseudomonas aeruginosa designated Ps 15. The minimal inhibitory concentrations of carbenicillin and gentamicin for Ps 15 in a 50% serum-Trypticase soy broth were 250 and 72.9 mug/ml, respectively. However, addition of triethylenetetramine dihydrochloride to the 50% serum-Trypticase soy broth reduced the minimal inhibitory concentration of both antibiotics approximately 10-fold. A comparison of the growth of Ps 15 in 50% serum-Trypticase soy broth containing either of the antibiotics showed that a rapid decrease in the percentage of survivors only occurred when the chelating agent was present.