Cross-protective effect of acid-adapted Salmonella enterica on resistance to lethal acid and cold stress conditions

AIMS

To evaluate the cross-protected Salmonella enterica cells under acid and cold stress conditions.

METHODS AND RESULTS

The acid-adapted S. enterica cells were exposed to pH 4.0 at 4 and 20 degrees C. Recovery of sublethally injured cells was estimated by the difference between the counts obtained on trypticase soy agar (TSA) and xylose lysine desoxycholate (XLD) agar. The survival curves of nonadapted and acid-adapted S. enterica cells at pH 4.0 were fitted with Weibull distribution model. The recovery behaviour of injured S. enterica cells was estimated by the modified Gompertz parameters. Acid-adapted S. enterica were more resistant to subsequent acid shock than the nonadapted cells. The numbers of nonadapted S. enterica cells were decreased by 457 and 755 log CFU ml(-1) at 4 and 20 degrees C after 12-day acid challenge, respectively. The acid adaptation induced cross-protection and viable nonculturable (VBNC) state against low acid and cold stresses. The 7-h adaptation showed the least recovery of injured cells.

CONCLUSION

The results suggest that acid-adapted S. enterica cells induced acid tolerance response and VBNC state.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results provide useful information for understanding the induction of cross-protected and VBNC pathogens under various stresses, which might be needed in designing new food preservation strategies.

Do stem cell markers have significant implication in breast cancer? Immunohistochemical study for CD44 and CD24

Abstract #5058

Background: We reported that breast cancer expressing CD44+CD24-/low showed a favorable prognosis in contrary to the in vitro/in vivo studies. We further followed this data up to 99 months and analyzed it according to CD44 expression, CD24 expression and hormone expression.
 Design: immunohistochemical stainings for CD44s and CD24 as well as prognostic markers including estrogen receptor, progesterone receptor, p53, and Her2/neu were done using tissue microarray blocks containing 645 consecutive cases of invasive breast carcinomas from 1993 to 1998. Mean follow up periods were 99.5 months. Cases were categorized into four subgroups (CD44-/CD24+, CD44+/CD24+, CD44-/CD24-, CD44+/CD24-) based on the immunohistochemical staining results and compared them with clinicopathologic parameters. Immunostainings for CD44s and CD24 interpreted as positive if at least 1% of tumor cells show distinct membranous and/or cytoplasmic stainings. In the positive group of CD24, we categorized it as three subgroups according to the degree of positivity.
 Results: CD44+CD24-/low group showed inversely associated with lymph node metastasis and the tumor stage than other subgroups (p=0.001 and p=0.018, respectively). And CD44+CD24-/low group was showed an increase in disease free survival and overall survival (p=0.003, p=0.002) In the subgroup analysis of CD24 expression (0, grade 1, grade 2, grade 3), the incidence of metastasis and death was more frequently observed in the cases with the higher expression of CD24. (DFS: p=0.03, OS: p=0.001). With respect to the CD44, CD44- group showed frequent metastasis and death (p=0.01, both) however, for the receptor positive groups, not CD44 but CD24 expression resulted negatively to the overall survival significantly(p=0.01, Relative risk=1.90) on multivariate analysis. For the receptor negative groups, especially triple negative group, lack of CD44 expression made overall decreased to 50%(p=0.03, hazard ratio=0.5)
 Conclusion: In contrast to cell line studies, CD44+CD24-/low phenotype is considered a favorable prognostic subgroup of breast cancer associated with less frequent nodal metastasis, lower tumor stage and infrequent distant metastasis. For receptor positive breast caner, CD24 expression effect DFS, OS significantly, and For receptor negative group, especially triple negative breast cancer, Lack of CD44 expression made and effect OS inversely.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5058.

Remarkable complete pathologic response rate after preoperative paclitaxel, gemcitabine, and trastuzumab chemotherapy in HER2 positive stage II/III breast cancer: a phase II multicenter study

Abstract #5105

Background: Preoperative paclitaxel (P) and gemcitabine (G) combination therapy given on D1/D8 every 3 weeks (wks) for 4 cycles was well tolerated and effective in stage II/III breast cancer (BC) in our previous phase II study, with an 18% pathological complete response (pCR) rate. Adding trastuzumab (H) to the preoperative chemotherapy increases both of the clinical and pathological response rates in HER2 positive BC patients (pts). Thus far, the highest pCR rate reported in the literature was obtained with anthracycline-based regimens in combination with trastuzumab. This study evaluated whether non-anthracycline combination chemotherapy with PGH could improve the pCR rate in HER2 positive BC. Methods: HER2 positive, stage II/III BC pts with cytologically confirmed axillary lymph node (LN), ≥ 18 years of age, with adequate organ function, and good performance status were eligible. No prior therapy was allowed. Pts received H intravenously (iv) at 4 mg/kg on D1 of the first cycle with subsequent weekly doses of 2 mg/kg in combination with P 80 mg/m2 and G 1,200 mg/m2, iv, on D1/D8 every 3 wks for 6 cycles. Within 2 wks postoperatively, patients received H 6 mg/kg every 3 wks for 11 cycles with tamoxifen or an aromatase inhibitor for 5 years if indicated. All pts received postoperative radiation therapy. Initial evaluation included sonogram and MRI of the breast, MUGA scan, or echocardiogram, and PET-CT. Results: All 53 planned pts were enrolled between April 2007 and February 2008. The median age was 43 years (range, 26–61 years), the median primary tumor size by sonogram was 5.3 cm (range, 2.0 to > 12 cm) with 89 % ≥ stage IIIA, 42% T3/T4, and 28% N3. Twenty four tumors (45%) were multiple and 20 tumors (38%) were ER positive. By May 2008, 47 patients completed surgery with a 74% breast conservation rate. Twenty-eight of 47 (60%; 95% CI, 45-72) patients achieved pCR in both the tumor and lymph node, with 68% (32/47; 95% CI, 54-80) pCR in the primary tumor, and 77% (36/47; 95% CI, 63-86) pCR in the axillary LN. Median metastatic focus in 21 positive LNs (n=11 pts) was 1 mm (range, <1–13mm). Grade III/IV adverse events (AE) were neutropenia (53%), febrile neutropenia (4%), and transient elevation of AST/ALT (9%). After 6 cycles of PGH chemotherapy, all patients maintained above normal LVEF. Conclusions: A remarkably high pCR was obtained by non-anthracyline based PGH combination therapy for HER2 positive stage II/III breast cancer. This combination is well tolerated with mild degree of AEs.
 Supported by NCC Grant No 0610240-3. Trastuzumab, paclitaxel, and gemcitabine were supplied by Roche, CJ Cheiljedang CO., and Eli Lilly and CO., respectively.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5105.

Evaluation of response to neoadjuvant chemotherapy in primary breast cancer using PET

Abstract #4019

Purpose
 To estimate the usefulness of PET scan to assess the response of neoadjuvant chemotherapy, PET scan results were compared with conventional imaging modalities(US and MRI).
 Patients and Methods
 Fourty-one patients undergoing neoadjuvant chemotherapy between December 2004 and March 2008 were included. PET scan was performed before and after chemotherapy. Pathologic results were classified into two groups; pathological complete response(pCR) and non-pCR. Clinical responses were assessed with the results of imaging modalities such as post-chemotherapy size or pSUV(postTx), size difference between treatment(delta) and reduction rate(RR) of size or pSUV, and they are compared with postoperative pathologic results.
 Results
 7 out of 41 patients (17.1%) had pCR. The results of US shows that postTx size (1.7±1.5cm) of pCR was not dfferent from those of non-pCR (3.6±3.0cm), and the delta (3.1±1.9cm) and RR (67.7±29.1%) of pCR were higher than those of non-pCR (1.3±1.3cm, 31.0±25.4%), respectively. As a result of MRI, postTx size, delta, RR of pCR was differ from those of non-pCR (1.0±1.7cm vs 2.8±1.7cm p<0.05; 4.5±1.0cm vs 2.3±1.8cm, p<0.05; 88.0±20.8% vs 44.6±24.7%, p<0.01). In PET scan, only postTx pSUV of pCR was differ from that of non-pCR (1.4±1.3 vs 5.3±8.3cm, p<0.05). As a result of receiver operating characteristic curve analyses for the prediction of pathological response of breast cancer, area under curve values (95% confidence interval) of US, MRI, PET for delta were 0.83(0.69∼0.98), 0.91(0.80∼1.01), 0.62(0.38∼0.86), and those of RR were 0.80(0.60∼0.99), 0.90(0.77∼1.02), 0.72(0.47∼0.96), respectively
 Conclusions
 We suggest that MRI is useful method to evaluate the response of neoadjuvant chemotherapy. Although PET scan shows less effective for evaluating the response of chemotherapy than MRI, PET scan with the ability to detect the distant metastatic lesions may be helpful to decide the proper management plans for advanced breast cancer.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4019.

Temperature and excitation density dependent photoluminescence of sputtering-induced GaAs/AlGaAs quantum dots

GaAs/AlGaAs quantum dots (QDs) are fabricated by low-energy ion beam sputtering and molecular beam epitaxy (MBE) re-growth. Temperature (6.5-78 K) and excitation power density (0.49-3.06 W cm(-2)) dependent photoluminescence (PL) are presented and discussed in detail. The low-temperature PL emission at 720 nm is attributed to GaAs QDs with height of ∼6.1 nm and base width of ∼23 nm, calculated based on the quantum box model with infinite potential barrier. The calculated QD dimensions are in good agreement with those obtained from atomic force microscopy (AFM) analysis. Nonradiative recombination and Auger-assisted recombination are found to be the main PL quenching mechanisms at high temperature.