18F-Fluorodeoxyglucose Positron Emission Tomography Parameters can Predict Long-Term Outcome Following Trimodality Treatment for Oesophageal Cancer

AIMS

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG-PET/CT) is routinely used for the pre-treatment staging of oesophageal or gastro-oesophageal junction cancers (EGEJC). The aim of this study was to identify objective ¹⁸FDG-PET/CT-derived parameters that can aid in predicting the patterns of recurrence and prognostication in patients with EGEJC.

PATIENTS AND METHODS

EGEJC patients referred for consideration of preoperative chemoradiation therapy were identified and clinicopathological data were collected. ¹⁸FDG-PET/CT imaging data were reviewed and correlated with treatment outcomes. Maximum standardised uptake value (SUV_max), metabolic tumour volume (MTV) and total lesion glycolysis were assessed and association with recurrence-free survival (RFS), locoregional recurrence-free survival (LR-RFS), oesophageal cancer-specific survival (ECSS) and overall survival were evaluated using receiver operating characteristic curves, as well as Cox regression and Kaplan-Meier models.

RESULTS

In total, 191 EGEJC patients completed trimodality treatment and 164 with ¹⁸FDG-PET/CT data were included in this analysis. At the time of analysis, 15 (9.1%), 70 (42.7%) and two (1.2%) patients were noted to have locoregional, distant and both locoregional and distant metastases, respectively. The median RFS was 30 months (9.6-50.4) and the 5-year RFS was 31.1%. The 5-year overall survival and ECSS were both noted to be 34.8%. Pre-treatment MTV₂₅ > 28.5 cm³ (P = 0.029), MTV₄₀ > 12.4 cm³ (P = 0.018) and MTV₅₀ > 10.2 cm³ (P = 0.005) predicted for worse LR-RFS, ECSS and overall survival for MTV definition of voxels ≥25%, 40% and 50% of SUV_max.

CONCLUSION

¹⁸FDG-PET/CT parameters MTV and total lesion glycolysis are useful prognostic tools to predict for LR-RFS, ECSS and overall survival in EGEJC. MTV had the highest accuracy in predicting clinical outcomes. The volume cut-off points we identified for different MTV thresholds predicted outcomes with significant accuracy and may potentially be used for decision making in clinical practice.

Does Loosening the Inclusion Criteria of the CROSS Trial Impact Outcomes in the Curative-Intent Trimodality Treatment of Oesophageal and Gastroesophageal Cancer Patients?

AIM

To determine the efficacy of preoperative chemoradiotherapy as per the CROSS protocol for oesophageal/gastroesophageal junction cancer (OEGEJC), when expanded to patients outside of the inclusion/exclusion criteria defined in the original clinical trial.

MATERIALS AND METHODS

Data were collected retrospectively on 229 OEGEJC patients referred for curative-intent preoperative chemoradiotherapy. Outcomes including pathological complete response (pCR), overall survival (OS), cancer-specific survival and recurrence-free survival (RFS) of patients who met CROSS inclusion criteria (MIC) versus those who failed to meet criteria (FMIC) were determined.

RESULTS

In total, 42.8% of patients MIC, whereas 57.2% FMIC; 16.6% of patients did not complete definitive surgery. The MIC cohort had higher rates of pCR, when compared with the FMIC cohort (33.3% versus 20.6%, P = 0.039). The MIC cohort had a better RFS, cancer-specific survival and OS compared with the FMIC cohort (P = 0.006, P = 0.004 and P = 0.009, respectively). Age >75 years and pretreatment weight loss >10% were not associated with a poorer RFS (P = 0.541 and 0.458, respectively). Compared with stage I-III patients, stage IVa was associated with a poorer RFS (hazard ratio (HR) = 2.158; 95% confidence interval (CI) = 1.339-3.480, P = 0.001). Tumours >8 cm in length or >5 cm in width had a trend towards worse RFS (HR = 2.060; 95% CI = 0.993-4.274, P = 0.052).

CONCLUSION

Our study showed that the robust requirements of the CROSS trial may limit treatment for patients with potentially curable OEGEJC and can be adapted to include patients with a good performance status who are older than 75 years or have >10% pretreatment weight loss. However, the inclusion of patients with celiac nodal metastases or tumours >8 cm in length or >5 cm in width may be associated with poor outcomes.

The effect of missing data and imputation on the detection of bias in cognitive testing using differential item functioning methods

Background

Item response theory (IRT) methods for addressing differential item functioning (DIF) can detect group differences in responses to individual items (e.g., bias). IRT and DIF-detection methods have been used increasingly often to identify bias in cognitive test performance by characteristics (DIF grouping variables) such as hearing impairment, race, and educational attainment. Previous analyses have not considered the effect of missing data on inferences, although levels of missing cognitive data can be substantial in epidemiologic studies.

Methods

We used data from Visit 6 (2016–2017) of the Atherosclerosis Risk in Communities Neurocognitive Study (N = 3,580) to explicate the effect of artificially imposed missing data patterns and imputation on DIF detection.

Results

When missing data was imposed among individuals in a specific DIF group but was unrelated to cognitive test performance, there was no systematic error. However, when missing data was related to cognitive test performance and DIF group membership, there was systematic error in DIF detection. Given this missing data pattern, the median DIF detection error associated with 10%, 30%, and 50% missingness was -0.03, -0.08, and -0.14 standard deviation (SD) units without imputation, but this decreased to -0.02, -0.04, and -0.08 SD units with multiple imputation.

Conclusions

Incorrect inferences in DIF testing have downstream consequences for the use of cognitive tests in research. It is therefore crucial to consider the effect and reasons behind missing data when evaluating bias in cognitive testing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01572-2.

Report from the Western Canadian Gastrointestinal Consensus Cancer Conference—Management of Total Neoadjuvant Therapy in Rectal Cancer

An educational session related to the Western Canadian Gastrointestinal Cancer Consensus Conference (WCGCCC) was held virtually on 14 October 2020. The WCGCCC is an interactive multidisciplinary conference attended by health care professionals from across Western Canada (British Columbia, Alberta, Saskatchewan, and Manitoba), who are involved in the care of patients with gastrointestinal cancer. Surgical, medical, and radiation oncologists; pathologists, radiologists, and allied health care professionals participated in presentation and discussion sessions for the purpose of developing the recommendations presented here. This consensus statement addresses current issues in the management of total neoadjuvant therapy in rectal cancer.

Are two too many when it comes to the treatment of anal canal cancer with concurrent radiation and mitomycin C?

3

Background: Concurrent chemoradiation (CRT) with 2 doses of 5-fluorouracil (5-FU) and mitomycin C (MMC) is the standard of care for anal canal cancer (ACC) in North America while 1 dose of MMC is an acceptable practice. Given the lack of randomized data of 1 vs 2 doses of MMC on disease outcomes, we have conducted a population-based study to elucidate the impact of 1 vs. 2 doses of MMC on patterns of treatment failure (POF) and outcomes in ACC treatment. Zainab Al Habsi, Aswin Abraham, Mustafa Al Balushi, Gabriella Tankel, Karen Mulder, Heather Warkentin, Dan Schiller, Keith Tankel, Nawaid Usmani, Diane Severin, Kim Paulson, Hatim Karachiwala, Clarence Wong, Tirath Nijjar, Kurian Joseph. Methods: Data was collected from the provincial cancer registry of patients with stage I-III ACC who were treated with concurrent CRT from 2000 to 2018. Recurrence free survival (RFS), overall survival (OS), and ACC specific survival were calculated. Results: 428 patients with a median age of 58 years (29-88 years) were included in this analysis. 234 (54.7%) patients received 1 dose of MMC and 194 (45.3%) received 2 doses of MMC. At a median follow-up of 78.5 months (5-252 months), 89 (20.8%) patients developed disease recurrence: 44 (10.3%) loco-regionally, 39 (9.1%) distally and 6 (1.4%) had both local and distant recurrences. Cox Regression analysis showed that the dosage of MMC did not have an impact on overall recurrence (HR = 0.883, p = 0.561), whereas stage III was associated with increased risk for recurrence (HR = 5.238, p = 0.021). Subgroup analysis showed an association of stage IIIb and IIIc with recurrence (HR = 13.33, p = 0.008 and HR = 6.933, p = 0.011 respectively), but was not impacted by the use of 1 vs. 2 doses of MMC. The dosage of MMC did not show any association with local recurrence (HR = 1.136, p = 0.655) or distant recurrence (HR = 0.743, p = 0.267). However, in Stage IIIc patients, 2 doses of MMC showed a trend towards improved distant RFS (HR = 0.626,p = 0.084). Conclusions: Our analysis showed that the patterns of failure and the risk of loco-regional and distant failures were similar between patients who received 1 vs. 2 doses of MMC for stage groups I to IIIc. These finding support routine use of single dose of MMC along with 5FU and radiotherapy for definite chemoradiation. However, a trend towards better RFS was demonstrated with a second dose of MMC in patients with stage IIIc disease.

Assessing Bias in Cognitive Testing for Older Adults with Sensory Impairment: An Analysis of Differential Item Functioning in the Baltimore Longitudinal Study on Aging (BLSA) and the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

OBJECTIVES

Vision and hearing impairments affect 55% of people aged 60+ years and are associated with lower cognitive test performance; however, tests rely on vision, hearing, or both. We hypothesized that scores on tests that depend on vision or hearing are different among those with vision or hearing impairments, respectively, controlling for underlying cognition.

METHODS

Leveraging cross-sectional data from the Baltimore Longitudinal Study of Aging (BLSA) and the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS), we used item response theory to test for differential item functioning (DIF) by vision impairment (better eye presenting visual acuity worse than 20/40) and hearing impairment (better ear .5-4 kHz pure-tone average > 25 decibels).

RESULTS

We identified DIF by vision impairment for tests whose administrations do not rely on vision [e.g., Delayed Word Recall both in ARIC-NCS: .50 logit difference between impaired and unimpaired (p = .04) and in BLSA: .62 logits (p = .02)] and DIF by hearing impairment for tests whose administrations do not rely on hearing [Digit Symbol Substitution test in BLSA: 1.25 logits (p = .001) and Incidental Learning test in ARIC-NCS: .35 logits (p = .001)]. However, no individuals had differences between unadjusted and DIF-adjusted measures of greater than the standard error of measurement.

CONCLUSIONS

DIF by sensory impairment in cognitive tests was independent of administration characteristics, which could indicate that elevated cognitive load among persons with sensory impairment plays a larger role in test performance than previously acknowledged. While these results were unexpected, neither of these samples are nationally representative and each has unique selection factors; thus, replication is critical.

Hippocampal avoidance in prophylactic cranial irradiation for small cell lung cancer: benefits and pitfalls

Small cell lung cancers (SCLC) are a group of cancers that are clinically and pathologically different from other lung cancers. They are associated with high recurrence rates and mortality, and many patients present with metastatic disease. Approximately ten percent of SCLC patients have brain metastases at time of diagnosis, and the cumulative incidence of brain metastases increases to more than fifty percent at two years, even with optimal treatment. Hence, in patients without brain metastases at presentation, prophylactic cranial irradiation (PCI) is an important component of treatment along with systemic chemotherapy and radiotherapy. The goal of PCI is to decrease the incidence of subsequent symptomatic brain metastases in patients who show an initial response to the systemic treatment. Various clinical trials have evaluated the utility of PCI and found substantial benefit. Unfortunately, the long-term toxicity associated with PCI, namely the neuro-cognitive impairment that may develop in patients as a result of the radiation toxicity to the hippocampal areas of the brain, has raised concern both for patients and their treating physicians. Various techniques have been tried to ameliorate the neuro-cognitive impairment associated with PCI, including pharmacological agents and highly conformal hippocampal avoidance radiation. All of these have shown promise, but there is a lack of clarity about the optimal way forward. Hippocampal avoidance PCI appears to be an excellent option and a number of groups are currently evaluating this technique. Although there is clear benefit with this specialized radiation treatment, there are also concerns about the risk of disease recurrence in the undertreated hippocampal areas. This review attempts to compile the available data regarding the benefits and pitfalls associated with hippocampal avoidance PCI in the setting of SCLC.

Dosimetric Parameters Predicting Late Small Bowel Toxicity in Patients With Rectal Cancer Receiving Neoadjuvant Chemoradiation

PURPOSE

The aim of this study was to identify dosimetric parameters that predict late small bowel (SB) toxicity after neoadjuvant long course chemoradiation (CRT) for rectal cancer.

METHODS AND MATERIALS

Four hundred eighty-six consecutive patients with locally advanced rectal cancers (clinical T3/T4 or N1/N2) who received CRT followed by surgery and had dosimetric data available for analysis were included in this study. The dose-volume relationship between small bowel irradiation and late small bowel toxicity was evaluated and a mathematical model to predict for late SB toxicity was derived.

RESULTS

Among the 486 patients with a median follow-up of 60 months from completion of radiation, 36 (7.4%) patients experienced ≥ grade 2 and 21 (4.3%) developed ≥ grade 3 late SB toxicity. A statistically significant association between the development of grade ≥3 late small bowel toxicity and the volume of small bowel irradiated was found at each dose level from 5 to 40 Gy (P < .001 for all dose volumes) in 5 Gy intervals. The average SB volume for patients who experienced grade ≥2 SB toxicity was 2149.9 cm³ and the average SB volume for patients who experienced grade ≥3 SB toxicity was 2179.9 cm³. The predicted V30 for a 5% risk for grade ≥2 SB toxicity was 101.5 cm³ and for grade ≥3 SB toxicity was 201.5 cm³. The volume of small bowel receiving at least 30 Gy (V30) was most strongly associated with grade ≥3 SB toxicity.

CONCLUSIONS

This study demonstrates the significant dose-volume relationship between volume of small bowel receiving 30 Gy (V30 Gy) and late grade ≥3 SB toxicity. When planning CRT for patients with rectal cancer, restricting V30 to <200 cm³ will be a useful guideline to minimize the 5 year grade ≥3 late SB toxicity to <5%.

Translational analysis from SCALOP trial: CCL5 as a prognostic biomarker and a potentially actionable target in locally advanced pancreatic cancer (LAPC)

740

Background: SCALOP was a multi-centre phase II RCT where 114 patients with LAPC were received 3 cycles of Gemcitabine and Capecitabine (GEMCAP) and those with stable/responding disease (n = 74) were randomised to Gem-RT or Cap-RT. The trial showed superiority of Cap-RT. Baseline blood samples of randomised patients were analysed for 35 circulating biomarkers. In vivo study was undertaken with candidate biomarker (CCL5) to test actionability. Methods: Patient bloods were tested using R&D multiplexed magnetic Luminex assays and IGF-1, TGF-b1 and b-NGF DuoSet ELISA. Orthotropic KrasG12D;P53R172H;PDXcre (KPC) tumors were implanted in Bl6-mice and treated with Gem, CCR5-inhibitor (CCR5i) maraviroc (MV), PD1 inhibitor (PD1i), PD1i+MV alone and in combination with MRI guided small animal Radiotherapy (RT). Immunophenotyping was performed by IHC and Aurora Cytek spectral flow cytometry. Results: Baseline biomarker data was available on 63/74 randomised patients. Of the 35 biomarkers tested, only CCL5 was found to be significantly associated with OS with a median OS of 18.5 (95% CI: 11.76-21.32) vs 11.3 (9.86-15.51) months (low vs high), and HR 1.37 (95% CI:1.04-3.65; p = 0.037) in the Cox multivariable model. Treatment of orthotopic KPC tumors revealed that combination of MV+PD1i+RT resulted in tumour growth inhibition and a switch of tumour macrophages from M2 to M1 accompanied by increase in infiltration of cytotoxic CD8+ Tcells and NK cells. Conclusions: Previous pre-clinical studies reported CCL5-CCR5 axis as a poor prognostic marker and a possible cause of immune-resistance in pancreatic cancer. Herein we have demonstrated in prospectively collected clinical trial blood samples that high circulating CCL5 is associated with poor prognosis in LAPC. CCR5 inhibitor in combination with RT+PD1i may overcome immune-resistance, and should be tested in clinical trials. Clinical trial information: 96169987 .

Urologic care and progression to end-stage kidney disease: a Chronic Kidney Disease in Children (CKiD) nested case-control study

INTRODUCTION

Children with chronic kidney disease (CKD) risk progressing to end-stage kidney disease (ESKD). The majority of CKD causes in children are related to congenital anomalies of the kidney and urinary tract, which may be treated by urologic care.

OBJECTIVE

To examine the association of ESKD with urologic care in children with CKD.

STUDY DESIGN

This was a nested case-control study within the Chronic Kidney Disease in Children (CKiD) prospective cohort study that included children aged 1-16 years with non-glomerular causes of CKD. The primary exposure was prior urologic referral with or without surgical intervention. Incidence density sampling matched each case of ESKD to up to three controls on duration of time from CKD onset, sex, race, age at baseline visit, and history of low birth weight. Conditional logistic regression analysis was performed to estimate rate ratios (RRs) for the incidence of ESKD.

RESULTS

Sixty-six cases of ESKD were matched to 153 controls. Median age at baseline study visit was 12 years; 67% were male, and 7% were black. Median follow-up time from CKD onset was 14.9 years. Seventy percent received urologic care, including 100% of obstructive uropathy and 96% of reflux nephropathy diagnoses. Cases had worse renal function at their baseline visit and were less likely to have received prior urologic care. After adjusting for income, education, and insurance status, urology referral with surgery was associated with 50% lower risk of ESKD (RR 0.50 [95% confidence interval [CI] 0.26-0.997), compared to no prior urologic care (Figure). After excluding obstructive uropathy and reflux nephropathy diagnoses, which were highly correlated with urologic surgery, the association was attenuated (RR 0.72, 95% CI 0.24-2.18).

DISCUSSION

In this study, urologic care was commonly but not uniformly provided to children with non-glomerular causes of CKD. Underlying specific diagnoses play an important role in both the risk of ESKD and potential benefits of urologic surgery.

CONCLUSION

Within the CKiD cohort, children with non-glomerular causes of CKD often received urologic care. Urology referral with surgery was associated with lower risk of ESKD compared to no prior urologic care but depended on specific underlying diagnoses.

Association Between Depressive Symptom Patterns and Clinical Profiles Among Persons Living with HIV

To describe patterns of depressive symptoms across 10-years by HIV status and to determine the associations between depressive symptom patterns, HIV status, and clinical profiles of persons living with HIV from the Multicenter AIDS Cohort Study (N = 980) and Women's Interagency HIV Study (N = 1744). Group-based trajectory models were used to identify depressive symptoms patterns between 2004 and 2013. Multinomial logistic regressions were conducted to determine associations of depression risk patterns. A 3-group model emerged among HIV-negative women (low: 58%; moderate: 31%; severe: 11%); 5-groups emerged among HIV-positive women (low: 28%; moderate: 31%; high: 25%; decreased: 7%; severe: 9%). A 4-group model emerged among HIV-negative (low: 52%; moderate: 15%; high: 23%; severe: 10%) and HIV-positive men (low: 34%; moderate: 34%; high: 22%; severe: 10%). HIV+ women had higher odds for moderate (adjusted odds ratio [AOR] 2.10, 95% CI 1.63-2.70) and severe (AOR 1.96, 95% CI 1.33-2.91) depression risk groups, compared to low depression risk. HIV+ men had higher odds for moderate depression risk (AOR 3.23, 95% CI 2.22-4.69), compared to low risk. The Framingham Risk Score, ART use, and unsuppressed viral load were associated with depressive symptom patterns. Clinicians should consider the impact that depressive symptoms may have on HIV prognosis and clinical indicators of comorbid illnesses.

Selected Lactobacillus strains isolated from sugary and milk kefir reduce Salmonella infection of epithelial cells in vitro

The isolation of potentially probiotic strains and the subsequent study of their properties are very important steps to gain insight in the health benefits ascribed to sugary and milk kefir. The aim of the present study was to characterise fifteen Lactobacillus strains isolated from these beverages by determining some surface properties and their ability to antagonise enterocyte cell damage after Salmonella infection in vitro. Lactobacillus surface properties were determined by hydrophobicity, autoaggregation, and coaggregation assays with Salmonella. In addition, lactobacilli adhesion to Caco-2/TC-7 cells and the effect on Salmonella invasion were evaluated. Finally, the disassembly of F-actin cytoskeleton on intestinal epithelial cells was assayed in vitro when Salmonella infection was performed in the presence of selected Lactobacillus strains. Ten out of the 15 strains showed a high adhesion capacity to Caco-2/TC-7 cells. Most of the strains were hydrophilic and non-autoaggregating. Strains isolated from sugary kefir were non-coaggregating with Salmonella, while strains Lactobacillus paracasei CIDCA 83120, 83121, 83123, 83124, 8339, 83102 isolated from milk kefir were able to coaggregate after 1 h. L. paracasei CIDCA 8339 and Lactobacillus kefiri CIDCA 83102 were able to diminish Salmonella invasion to the enterocytes. An antagonistic effect on cytoskeleton disruption elicited by the pathogen was also demonstrated. Our results suggest that both strains isolated from milk kefir could be considered as appropriate probiotic candidates.

Targeting radiation resistance in p53 mutant tumors with AKT inhibitors

11115

Background: Increasing our understanding of how resistance to radiation occurs, helps us develop more efficient and personalised radiotherapy treatments for cancer patients. Through molecular dissection of events that drive tumour initiation and progression, we have uncovered a functional connection between the most frequent oncogenic mutations that are likely to contribute to therapeutic resistance in 30% of all human tumours. Mutations activating the "AKT" signalling pathway and inactivation of the “TP53” tumour suppressor gene are common mechanisms that cancer cells require to proliferate and escape pre-programmed cell death. We find that in combination these events lead to therapeutic resistance that is reversible by the AKT clinical candidate, MK-2206 and the PI3K inhibitor PI-103. Methods: Using a combination of in vivo and in vitro techniques we have tracked the molecular mechanism for AKT mediated resistance to treatment in solid tumours. This has helped us to simultaneously derive potential biomarkers that could highlight where the greatest efficacy may be achieved in clinical practise. Results: Tumours employ many strategies to inactivate p53; however sequence mutations that result in mutant p53 protein (p53mut) are most often observed. p53mut tumours not only fail to respond to DNA damaging therapy, but are also described to promote therapeutic resistance by dominant negative suppression of p53 dependent promoter activity. We demonstrate that AKT inhibitors- and as proof of concept, the clinical candidate AKT inhibitor, MK-2206, and PI3K inhibitor, PI-103, are effective in treatment of mice with therapeutically resistant tumours with elevated AKT and carrying p53mut. AKT inhibition promotes reduced cellular levels of p53mut via a novel mechanism and promoted re-engagement of cell cycle arrest, senescence and increased sensitivity to ionising radiation in both in vivo and in vitro systems. Conclusions: We show that AKT inhibitors sensitise xenografts carrying p53 mutations to DNA damaging therapy. We have also been identifying potential molecular markers to select the cohort of patient most likely to benefit from this treatment.

Inhibitory activity of cheese whey fermented with kefir grains

We investigated the chemical and microbiological compositions of three types of whey to be used for kefir fermentation as well as the inhibitory capacity of their subsequent fermentation products against 100 Salmonella sp. and 100 Escherichia coli pathogenic isolates. All the wheys after fermentation with 10% (wt/vol) kefir grains showed inhibition against all 200 isolates. The content of lactic acid bacteria in fermented whey ranged from 1.04 × 10(7) to 1.17 × 10(7) CFU/ml and the level of yeasts from 2.05 × 10(6) to 4.23 × 10(6) CFU/ml. The main changes in the chemical composition during fermentation were a decrease in lactose content by 41 to 48% along with a corresponding lactic acid production to a final level of 0.84 to 1.20% of the total reaction products. The MIC was a 30% dilution of the fermentation products for most of the isolates, while the MBC varied between 40 and 70%, depending on the isolate. The pathogenic isolates Salmonella enterica serovar Enteritidis 2713 and E. coli 2710 in the fermented whey lost their viability after 2 to 7 h of incubation. When pathogens were deliberately inoculated into whey before fermentation, the CFU were reduced by 2 log cycles for E. coli and 4 log cycles for Salmonella sp. after 24 h of incubation. The inhibition was mainly related to lactic acid production. This work demonstrated the possibility of using kefir grains to ferment an industrial by-product in order to obtain a natural acidic preparation with strong bacterial inhibitory properties that also contains potentially probiotic microorganisms.

Exopolysaccharides produced by Lactobacillus and Bifidobacterium strains abrogate in vitro the cytotoxic effect of bacterial toxins on eukaryotic cells

AIMS

To evaluate the capability of the exopolysaccharides (EPS) produced by lactobacilli and bifidobacteria from human and dairy origin to antagonize the cytotoxic effect of bacterial toxins.

METHODS AND RESULTS

The cytotoxicity of Bacillus cereus extracellular factors on Caco-2 colonocytes in the presence/absence of the EPS was determined by measuring the integrity of the tissue monolayer and the damage to the cell membrane (extracellular lactate dehydrogenase activity). Additionally, the protective effect of EPS against the haemolytic activity of the streptolysin-O was evaluated on rabbit erythrocytes. The EPS produced by Bifidobacterium animalis ssp. lactis A1 and IPLA-R1, Bifidobacterium longum NB667 and Lactobacillus rhamnosus GG were able to counteract the toxic effect of bacterial toxins on the eukaryotic cells at 1mg ml(-1) EPS concentration. The EPS A1 was the most effective in counteracting the effect of B. cereus toxins on colonocytes, even at lower doses (0·5mg ml(-1) ), whereas EPS NB667 elicited the highest haemolysis reduction on erythrocytes.

CONCLUSIONS

The production of EPS by lactobacilli and bifidobacteria could antagonize the toxicity of bacterial pathogens, this effect being EPS and biological marker dependent.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work allows gaining insight about the mechanisms that probiotics could exert to improve the host health.

Preservation of probiotic strains isolated from kefir by spray drying

AIMS

This work aims to investigate the survival of Lactobacillus kefir CIDCA 8348, Lactobacillus plantarum CIDCA 83114 and Saccharomyces lipolytica CIDCA 812, all isolated from kefir, during spray drying and subsequent storage.

METHODS AND RESULTS

Micro-organisms were grown in De Man, Rogosa, Sharpe (MRS) or yeast medium (YM) medium and harvested in the stationary phase of growth. The thermotolerance in skim milk (D and Z values), the survival of spray drying at different outlet air temperatures and subsequent storage in different conditions during 150 days were studied. The resistance to the heat treatments was higher in Lact. plantarum compared to Lact. kefir and S. lipolytica. The three micro-organisms studied varied considerably in their ability to survive to spray drying processes. Lactobacillus plantarum showed the highest survival rate for all the tested outlet air temperatures and also to the further storage in the dried state. The survival rates of Lact. kefir and S. lipolytica through drying and subsequent storage in the dried state decreased when the drying outlet air temperatures increased.

CONCLUSIONS

Spray drying is a suitable method to preserve micro-organisms isolated from kefir grains. A high proportion of cells were still viable after 80 days of storage at refrigerated temperatures.

SIGNIFICANCE AND IMPACT OF STUDY

It is the first report about spray-dried probiotic strains isolated from kefir grain and contributes to the knowledge about these micro-organisms for their future application in novel dehydrated products.

Protective action of Lactobacillus kefir carrying S-layer protein against Salmonella enterica serovar Enteritidis

Eight Lactobacillus kefir strains isolated from different kefir grains were tested for their ability to antagonize Salmonella enterica serovar Enteritidis (Salmonella enteritidis) interaction with epithelial cells. L. kefir surface properties such as autoaggregation and coaggregation with Salmonella and adhesion to Caco-2/TC-7 cells were evaluated. L. kefir strains showed significantly different adhesion capacities, six strains were able to autoaggregate and four strains coaggregated with Salmonella. Coincubation of Salmonella with coaggregating L. kefir strains significantly decreased its capacity to adhere to and to invade Caco-2/TC-7 cells. This was not observed with non coaggregating L. kefir strains. Spent culture supernatants of L. kefir contain significant amounts of S-layer proteins. Salmonella pretreated with spent culture supernatants (pH 4.5-4.7) from all tested L. kefir strains showed a significant decrease in association and invasion to Caco-2/TC-7 cells. Artificially acidified MRS containing lactic acid to a final concentration and pH equivalent to lactobacilli spent culture supernatants did not show any protective action. Pretreatment of this pathogen with spent culture supernatants reduced microvilli disorganization produced by Salmonella. In addition, Salmonella pretreated with S-layer proteins extracted from coaggregating and non coaggregating L. kefir strains were unable to invade Caco-2/TC-7 cells. After treatment, L. kefir S-layer protein was detected associated with Salmonella, suggesting a protective role of this protein on association and invasion.

Polysaccharide production by kefir grains during whey fermentation

Fermentation of deproteinised whey with kefir grains CIDCA AGK1 was studied focusing on polysaccharide production from lactose. Kefir grains were able to acidify whey at different rates depending on the grain/whey ratio. During fermentation, kefir grains increased their weight and a water-soluble polysaccharide was released to the media. Exopolysaccharide concentration increased with fermentation time, reaching values of 57.2 and 103.4 mg/l after 5 days of fermentation in cultures with 10 and 100 g kefir grains/l, respectively. The polysaccharide fraction quantified after fermentation corresponded to the soluble fraction, because part of the polysaccharide became a component of the grain. Weight of kefir grains varied depending on the time of fermentation. Polysaccharide production was affected by temperature. Although the highest concentration of polysaccharide in the media was observed at 43 degrees C at both grain/whey ratios, the weight of the grains decreased in these conditions. In conclusion, kefir grains were able to acidify deproteinised whey, reducing lactose concentration, increasing their weight and producing a soluble polysaccharide.

Chemical and microbiological characterisation of kefir grains

Chemical and microbiological composition of four Argentinean kefir grains from different sources as well as characteristics of the corresponding fermented milk were studied. Kefir grains CIDCA AGK1, AGK2 and AGK4 did not show significant differences in their chemical and microbiological composition. In contrast, protein and yeast content of AGK3 was higher than in the other grains. Although grain microflora comprised lactobacilli, lactococcus, acetic acid bacteria and yeast, we found an important difference regarding species. Lactococcus lactis subsp. lactis, Lactobacillus kefir, Lactobacillus plantarum, Acetobacter and Saccharomyces were present in all types of kefir grain. While Leuconostoc mesenteroides was only isolated from grains CIDCA AGK1 and Lactococcus lactis subsp. lactis biovar diacetylactis, Lactobacillus parakefir and Kluyveromyces marxianus were only isolated from CIDCA AGK2 grains. All grains produced acid products with pH between 3.5 and 4.0. The apparent viscosity of AGK1 fermented milk was greater than the product obtained with AGK4. All fermented milks had inhibitory power towards Escherichia coli but AGK1 and AGK2 supernatants were able to halt the bacterial growth for at least 25 h. Grain weight increment in AGK1, AGK2 and AGK3 during growth in milk did not show significant differences. Despite their fermenting activity, AGK4 grains did not increase their weight.

Inhibitory power of kefir: the role of organic acids

Milk and MRS broth fermented with kefir grains from different households were examined for inhibitory activity toward gram-negative and gram-positive strains. Fermented milk obtained with 10 g per 100 ml of inoculum (final pH 3.32 to 4.25) and MRS broth fermented with 1 and 10 g per 100 ml of inocula (final pH 4.18 to 5.25) had inhibitory power demonstrated by spot test and agar well diffusion assay. This inhibitory effect could be assigned to the undissociated form of lactic and acetic acid produced during the fermentation process. Kefir supernatants inhibited the growth of Escherichia coli 3 in nutrient broth at 37 degrees C for 24 h. However, supernatants of yogurt or milk artificially acidified with lactic and acetic acids allowed the growth of E. coli 3 in the same conditions. A bacteriostatic effect of milk fermented with kefir grains over E. coli 3 was also demonstrated.

Characterization of kefir grains grown in cows' milk and in soya milk

Kefir is a refreshing fermented milk with a slightly acidic taste obtained by incubating milk with kefir grains (Saloff-Coste, 1996). Kefir grains are a complex mixture of lactic acid bacteria and yeasts in a strong and specific association. They are characterized by an irregular form, a folded and uneven surface and a white or slightly yellow colour. They are tough and resilient and have a characteristic acid taste (Bottazzi et al. 1994). The basic microflora contains lactococci, homofermentative and heterofermentative lactobacilli, yeasts and acetic acid bacteria (Bottazzi et al. 1994; Rea et al. 1996). Among the yeasts isolated from grains and identified are Candida kefir, Saccharomyces cerevisiae, Sac. delbrueckii, Cand. holmii, Sac. unisporus and Sac. lipolytica (Angulo et al. 1993; Marshall, 1993; Garrote et al. 1997). Lactobacillus brevis, Lb. viridescens, Lb. casei, Lb. kefir, Lb. kefiranofaciens, Lb. kefirgranum, Lb. parakefir, Leuconostoc spp. and Lactococcus lactis are among the lactic acid bacteria present in the grains (Marshall et al. 1984; Toba et al. 1991; Takizawa et al. 1994; Garrote et al. 1997). The mixed microflora of yeasts and bacteria is held together by a matrix containing (g/kg dry weight) protein 340, polysaccharide 470 (Ottogalli et al. 1973).

The study of kefir grains in milk has been centred on the characteristics of the polysaccharide produced by lactobacilli within the grain (Yokoi et al. 1991). This polysaccharide, named kefiran, is composed of glucose and galactose (Yokoi et al. 1991). It has been suggested that proteins are incorporated from the growth media (Bassette & Acosta 1988), but no details about structure and composition are available.

Soyabeans are an important component of the diet in many countries and have been used to obtain fermented products such as sogurt (Mann, 1991). Special attention has been given to the growth of, and sugar utilization by, Bifidobacterium spp., Lb. delbrueckii subsp. bulgaricus and Streptococcus thermophilus in soya milk (Buono et al. 1990; Murti et al. 1993; Ankenman Granata & Morr, 1996). To our knowledge, there have been no attempts to ferment soya milk with kefir grains.

The aim of this study was to investigate the growth of kefir grains in soya milk and the composition of these grains, focusing on the matrix proteins.

Remember to consider dermatophyte infection when dealing with recalcitrant dermatoses

BACKGROUND

Superficial fungal infections of the skin are among the most common infections encountered in medicine. The diagnosis is easily confirmed with simple office-based procedures. In certain clinical situations, the diagnosis can be elusive.

METHODS

We analyzed clinical data on five patients who came in referral for treatment of a recalcitrant dermatosis.

RESULTS

All patients had their diagnosis confirmed by a positive potassium hydroxide preparation from skin scrapings or by a skin biopsy positive for fungal elements. All showed clinical improvement and ultimate resolution of their skin lesions with topical and/or systemic antifungal therapy.

CONCLUSIONS

Diagnosis can be complicated by previous use of corticosteroid-containing topical and/or systemic agents, a clinical history closely resembling that of a photosensitive disorder, and a lack of clinical-histopathologic correlation. Laboratory procedures and skin biopsy of an ambiguous appearing lesion can be diagnostic, but an accurate diagnosis is dependent on communication between the clinician and the pathologist. We recommend that office-based procedures be done early in treatment so that subsequent efforts can be directed toward providing appropriate therapies.