Bactericidal efficiency and mode of action: a comparative study of photochemistry and photocatalysis.

In order to compare the disinfection potential of photocatalysis and photochemistry, the effects of these two processes on bacteria in water were investigated under exposure to UV-A and UV-C. The well-known bacterial model Escherichia coli (E. coli) was used as the experimental organism. Radiation exposure was produced with an HPK 125 W lamp and the standard TiO(2) Degussa P-25 was used as the photocatalyst. Firstly, the impact of photocatalysis and photochemistry on the cultivability of bacterial cells was investigated. UV-A radiation resulted in low deleterious effects on bacterial cultivability but generated colonies of size smaller than average. UV-C photocatalysis demonstrated a greater efficiency than UV-A photocatalysis in altering bacterial cultivability. From a cultivability point of view only, UV-C radiation appeared to be the most deleterious treatment. A rapid epifluorescence staining method using the LIVE/DEAD Bacterial Viability Kit was then used to assess the modifications in bacterial membrane permeability. UV-A radiation did not induce any alterations in bacterial permeability for 420 min of exposure whereas only a few minutes of exposure to UV-C radiation, with the same total radiance intensity, induced total loss of permeability. Moreover, after 20 and 60 min of exposure to UV-C and UV-A photocatalysis respectively, all bacteria lost their membrane integrity, suggesting that the bacterial envelope is the primary target of reactive oxygen species (ROS) generated at the surface of TiO(2) photocatalyst. These results were further confirmed by the formation of malondialdehyde (MDA) during the photocatalytic inactivation of bacterial cells and suggest that destruction of the cell envelope is a key step in the bactericidal action of photocatalysis. The oxidation of bacterial membrane lipids was also correlated with the monitoring of carboxylic acids, which can be considered as representatives of lipid peroxidation by-products. Finally, damages to bacterial morphology induced by UV-C photocatalysis and photochemistry were investigated through Scanning electron microscopy (SEM). Bacterial cells were observed on microscopy pictures at exposure durations corresponding to a loss of cultivability. After 90 min of exposure to UV-C radiation, bacterial cells showed little alteration of their outer membrane whereas they suffered deep deleterious damages under UV-C photocatalysis exposure.

Atypical citrate-fermenting Lactococcus lactis strains isolated from dromedary's milk.

AIM: The aim was to isolate and characterize Lactococcus strains with new properties compared to those of usual Lactococcus dairy starters derived from cow's milk. METHODS AND RESULTS: Algerian dromedary's milk was screened for proteolytic isolates able to grow rapidly on agar milk medium. PCR experiments revealed that 74 proteolytic isolates belonged to the genus Lactococcus and harboured the prtP gene encoding the lactococcal cell-surface proteinase. Among these, 85% were able to ferment citrate (Cit(+) phenotype) and were classified as Lactococcus lactis ssp. lactis biovar. diacetylactis. This classification was confirmed after sequencing of the 16S rDNA gene of five Cit(+) isolates. In contrast to dairy lactococci described in the literature, several Cit(+) isolates exhibited a tolerance to 50 degrees C (Ther(+)) and alkaline pH. Two genetic approaches allowed to show the presence of four independent plasmids (so-called pTher, pPrt, pLac, pCit) associated with the four respective phenotypes: Ther(+), cell-surface proteinase activity PrtP (PrtP(+)), lactose catabolism (Lac(+)) and citrate utilization (Cit(+)). Two types of pCit plasmid were amplified by inverse PCR: class 1 was characterized by a 9-kb plasmid harbouring the expected lactococcal citQRP operon and class 2 by a 23-kb plasmid harbouring the Leuconostoc cit cluster (citI-CitMCDEFGRP). CONCLUSIONS: This work enlarges knowledge of the biovariety diacetylactis by far mainly limited to the citrate-fermenting ability and suggests that the cit plasmid system of some lactococcal strains could have been acquired from another lactic acid bacteria (Leuconostoc spp.). SIGNIFICANCE AND IMPACT OF THE STUDY: This study reveals new potential dairy lactococci starters of the biovariety diacetylactis able to grow rapidly in milk at a higher temperature in addition to their casein, lactose and citrate-utilizing abilities.

Peptidases specific for proline-containing peptides and their unusual peptide-dependent regulation in Oenococcus oeni.

AIMS: Growth of the lactic acid bacterium (LAB) Oenococcus oeni, which is involved in malolactic fermentation during the winemaking process, is stimulated by peptides originating from yeast. In this study, we investigated the impact of peptides on O. oeni growth, peptidase activity and the expression of genes encoding the studied peptidases. METHODS AND RESULTS: Low levels of PepN activity and very high levels of PepI activity were observed in O. oeni, whereas levels of PepX activity were intermediate. The level of biosynthesis of these O. oeni peptidases was shown to depend on peptides present in the culture medium. These results were confirmed by transcriptional analyses of putative pep genes. The mechanism of repression by peptides did not involve a CodY-like regulator. CONCLUSIONS: Peptides from yeast decrease the levels of enzymatic activity and relative gene expression of O. oeni peptidases. Peptidases specific for proline-containing peptides are important for O. oeni nitrogen metabolism. SIGNIFICANCE AND IMPACT OF THE STUDY: We report here for the first time that the enzymes involved in the assimilation of proline-containing peptides by O. oeni differ from the well-described proteolytic system of milk LAB. This may reflect a specific adaptation to the wine environment.

Comparative analysis of the exopolysaccharide biosynthesis gene clusters from four strains of Lactobacillus rhamnosus.

The exopolysaccharide (EPS) biosynthesis gene clusters of four Lactobacillus rhamnosus strains consist of chromosomal DNA regions of 18.5 kb encoding 17 ORFs that are highly similar among the strains. However, under identical conditions, EPS production varies considerably among these strains, from 61 to 1611 mg l(-1). Fifteen genes are co-transcribed starting from the first promoter upstream of wzd. Nevertheless, five transcription start sites were identified by 5'-RACE PCR analysis, and these were associated with promoter sequences upstream of wzd, rmlA, welE, wzr and wzb. Six potential glycosyltransferase genes were identified that account for the assembly of the heptasaccharide repeat unit containing an unusually high proportion of rhamnose. Four genes involved in the biosynthesis of the sugar nucleotide precursor dTDP-L-rhamnose were identified in the EPS biosynthesis locus, which is unusual for lactic acid bacteria. These four genes are expressed from their own promoter (P2), as well as co-transcribed with the upstream EPS genes, resulting in coordinated production of the rhamnose precursor with the enzymes involved in EPS biosynthesis. This is believed to be the first report demonstrating that the sequence, original organization and transcription of genes encoding EPS production are highly similar among four strains of Lb. rhamnosus, and do not vary with the amount of EPS produced.

Impact of EGFR expression on colorectal cancer patient prognosis and survival.

BACKGROUND: Epidermal growth factor receptor (EGFR) is overexpressed in many types of cancers, especially colorectal cancer (CRC), and seems to reflect more aggressive histological and clinical behaviors. The aim of this study was to evaluate EGFR immunohistochemical reactivity in CRC biopsies, and to analyze its relationship with various histological and clinical characteristics and survival. PATIENTS AND METHODS: A composite EGFR score, obtained by multiplying the grade (% positive cells) by the intensity of labeling (0-9) was used to define patients with low or high EGFR expression whose clinicopathological features were then compared. Univariate tests and multivariate Cox proportional hazards model were applied for data analysis. RESULTS: Tissue sections from 150 CRC patients with a median follow-up of 40 months were examined. Median patient age at diagnosis was 70 years (range 38-89 years). EGFR reactivity was positive for 143 patients (97%) and high for 118 (80%). According to multivariate analysis, EGFR overexpression was significantly associated with tumor stage, with a higher percentage of EGFR overexpression in T3 than T4 (P=0.003) and not with overall survival. CONCLUSIONS: EGFR was overexpressed in this CRC patient population and was significantly associated with TNM (tumor-node-metastasis) stage T3. In the context of a new therapeutic strategy using EGFR-targeted therapies, although EGFR remains a controversial prognostic factor, this expression-stage association may play a crucial role in a decision to initiate an adjuvant treatment.

[Long term results of exclusive chemotherapy for glottic squamous cell carcinoma complete clinical responders after induction chemotherapy]. / Résultats à long-terme de la chimiothérapie exclusive des cancers épidermoïdes glottiques.

OBJECTIVES: To evaluate the long-term results of exclusive chemotherapy for T1-T3N0M0 glottic squamous cell carcinoma complete clinical responders after induction chemotherapy. MATERIAL AND METHODS: Between 1985 and 2000, 69 patients with glottic squamous cell carcinoma complete clinical responders after induction chemotherapy were managed with exclusive chemotherapy at our department. Chemotherapy associated platinum and fluorouracil. This retrospective analysis evaluated actuarial survival, treatment morbidity, oncologic events and laryngeal preservation. Various independent factors were tested for potential correlation with survival and local recurrence. RESULTS: The 5-year Kaplan-Meier actuarial survival, local control, lymph node control estimate were 83,6%, 64,8%, 98,6% respectively. Chemotherapy never resulted in death. The 10-year actuarial metachronous second primary tumors estimate was 32%. The overall laryngeal preservation rate was 98,6%. CONCLUSION: Altogether our data and the review of the literature suggest that in patients achieving a complete clinical response after and induction based chemotherapy regimen, the completion of an exclusive chemotherapy regimen appears to be a valid alternative to the conventional use of radiotherapy or chemo-radiation protocols.

[Volume-effect and radiotherapy [II]. Part II: volume-effect and normal tissue]. / Effet volume en radiothérapie [II]. Deuxième partie : volume et tolérance des tissus sains.

The first part of our work has focused on the relationship between tumor volume and tumor control. Indeed, it is well known that the importance of irradiated volume could be a main parameter of radiation-induced complications. Numerous mathematical models have described the correlation between the irradiated volume and the risk of adverse effects. These models should predict the complication rate of each treatment planning. At the present time late effects have been the most studied. In this report we firstly propose a review of different mathematical models described for volume effect. Secondly, we will discuss whether these theoretical considerations can influence our view of radiation treatment planning optimization.

Nasopharyngeal carcinomas: an update.

Among the group of head and neck cancers, nasopharyngeal carcinomas (NPC) represent a distinct entity in terms of their epidemiology, clinical presentation, biological markers, carcinogenic risk factors, prognostic factors, treatment and outcome. Undifferentiated NPC (UCNT), the most frequent histological type, is endemic in certain regions, especially in South East Asia. The disease has also been associated with the presence of the Epstein-Barr Virus (EBV). Although NPC is a radiosensitive and chemosensitive tumour, a substantial number of patients develop local recurrence or distant metastases. For patients with locoregional advanced disease, it is well known that conventional radiotherapy is insufficient in terms of both the local control rates and distant metastases. New techniques of radiation and new combined radiotherapy and chemotherapy modalities have been evaluated in numerous clinical trials in recent years. The purpose of this article is to review the current knowledge in terms of the epidemiology, biology, prognosis, management and outcome of patients with NPC.

[Operable stage IB and II cancer of the uterine neck: retrospective comparison between preoperative utero-vaginal curietherapy and initial surgery followed by radiotherapy]. / Cancer du col utérin stades IB et II opérable: comparaison rétrospective entre curiethérapie utérovaginale préopératoire et chirurgie première suivies d'une radiothérapie.

PURPOSE: To identify prognostic factors and treatment toxicity in a series of operable stages IB and II cervical carcinomas. PATIENTS AND METHODS: Between May 1972 and January 1994, 414 patients (pts) with cervical carcinoma staged according to the 1995 FIGO staging system underwent radical hysterectomy with (n = 380) or without (n = 34) bilateral pelvic lymph node dissection. Lateral ovarian transposition to preserve ovarian function was performed on 12 pts. The methods of radiation therapy (RT) were not randomised and depended on the usual practices of the surgical teams. Group I: 168 pts received postoperative RT (64 pts received vaginal brachytherapy alone [mean total dose (MD): 50 Gy], 93 pts had external beam pelvis RT (EBPRT) [MD: 45 Gy over 5 weeks] followed by vaginal brachytherapy [MD: 20 Gy], and 11 pts had EBPRT alone [MD: 50 Gy over 6 weeks]. Group II: 246 pts received preoperative utero-vaginal brachytherapy [MD: 65 Gy], and 32 of theses 246 pts also received postoperative EBPRT [MD: 45 Gy over 5 weeks] delivered to the parametric and the pelvic lymph nodes with a midline pelvic shield. The mean follow-up was 106 months. RESULTS: The 10-year disease-free survival (DFS) rate was 80%. From 75 recurrences, 35 were isolated locoregional. Multivariate analysis showed that independent factors decreasing the probability of DFS were: both exo and endocervical tumour site (p = 0.047), lymph-vascular space invasion (p = 0.041), age < or = 51 yr (p = 0.013), 1995 FIGO staging system (stage IB1 vs stage IIA, p = 0.004, stage IB1 vs stage IB2, p = 0.0009, and stage IB1 vs stage IIB with 1/3 proximal parametrical infiltration, p = 0.00002), and histological pelvic involved lymph nodes (p = 0.00009). Methods of adjuvant RT did not influence the probability of DFS (group I vs group II, p = 0.10). The postoperative complication rate was 10.2% in group I and 8.9% in group II (p = 0.7) but the postoperative urethral complication rate necessitating surgical intervention with reimplantation was lower in group I than in group II (0.6% vs 2.3%, respectively, p = 0.03). The 10-year rate for grade 3 and 4 late radiation complications according to the LENT-SOMA scoring system was 10.4%. EPRT significantly increased the 10-year rate for grade 3 and 4 late radiation complications (yes vs no: 22% vs 7%, respectively, p = 0.0002). CONCLUSION: In our series, the methods of adjuvant RT (primary surgery vs preoperative uterovaginal brachytherapy) do not seem to influence the prognosis of the stage IB, IIA, and IIB (with 1/3 proximal parametrical involvement only) cervical carcinomas. The postoperative EPRT applied according to histopathological risk factors after surgical treatment increases the risk of late radiation complications.

[Radiotherapy of cancers of the pancreas and extrahepatic biliary tree. Gross tumor volume (GTV). Clinical target volume (CTV)]. / Radiothérapie des cancers du pancréas et des cancers des voies biliaires extra-hépatiques. Volume tumoral macroscopique (GTV). Volume-cible anatomoclinique (CTV).

Anatomical data of pancreas, biliary tree, regional lymph nodes is required to define GTV and CTV. In case of postoperative irradiation, CTV is designed in collaboration with radiation oncologist and surgeon oncologist. For exclusive radiotherapy, endodigestive ultrasonography, CT scan and MRI could help radiation oncologist defining GTV. Although, accuracy of all the imaging techniques in past years remains poor. Currently, no available literature is published regarding security margins for the definition of CTV. Therefore, recommendations according to clinical experience are proposed.

Autoregulation of the biosynthesis of the CcpA-like protein, PepR1, in Lactobacillus delbrueckii subsp bulgaricus.

PepR1 from Lactobacillus delbrueckii subsp bulgaricus (Lb. bulgaricus) is involved in biosynthesis regulation of the prolidase PepQ. In this paper, we demonstrated that Lb. bulgaricus PepR1 biosynthesis is not constitutive like those of several bacteria but is auto-regulated and depends on the glucose concentration of the culture medium. We propose a model for PepQ regulation by PepR1.

Hydrolysis of sequenced beta-casein peptides provides new insight into peptidase activity from thermophilic lactic acid bacteria and highlights intrinsic resistance of phosphopeptides.

The peptidases of thermophilic lactic acid bacteria have a key role in the proteolysis of Swiss cheeses during warm room ripening. To compare their peptidase activities toward a dairy substrate, a tryptic/chymotryptic hydrolysate of purified beta-casein was used. Thirty-four peptides from 3 to 35 amino acids, including three phosphorylated peptides, constitute the beta-casein hydrolysate, as shown by tandem mass spectrometry. Cell extracts prepared from Lactobacillus helveticus ITG LH1, ITG LH77, and CNRZ 32, Lactobacillus delbrueckii subsp. lactis ITG LL14 and ITG LL51, L. delbrueckii subsp. bulgaricus CNRZ 397 and NCDO 1489, and Streptococcus thermophilus CNRZ 385, CIP 102303, and TA 060 were standardized in protein. The peptidase activities were assessed with the beta-casein hydrolysate as the substrate at pH 5.5 and 24 degrees C (conditions of warm room ripening) by (i) free amino acid release, (ii) reverse-phase chromatography, and (iii) identification of undigested peptides by mass spectrometry. Regardless of strain, L. helveticus was the most efficient in hydrolyzing beta-casein peptides. Interestingly, cell extracts of S. thermophilus were not able to release a significant level of free proline from the beta-casein hydrolysate, which was consistent with the identification of numerous dipeptides containing proline. With the three lactic acid bacteria tested, the phosphorylated peptides remained undigested or weakly hydrolyzed indicating their high intrinsic resistance to peptidase activities. Finally, several sets of peptides differing by a single amino acid in a C-terminal position revealed the presence of at least one carboxypeptidase in the cell extracts of these species.

Linac radiosurgery for cerebral arteriovenous malformations: results in 169 patients.

PURPOSE: To present the SALT group results using Linac radiosurgery (RS) for AVM in 169 evaluable patients treated from January 1990 thru December 1993. METHODS AND MATERIALS: Median age was 33 years (range 6-68 years). Irradiation was the only treatment in 55% patients. Other treatment modalities had been used prior to RS in 45%: one or more embolizations in 36%, surgery in 6%, and embolization and surgery in 3% patients. Nidus were supratentorial in 94% patients, infratentorial in 6% patients. Circular 15 MV x-ray minibeams (6-20 mm) were delivered in coronal arcs by a GE-CGR Saturne 43 Linac. Patient set-up included a Betti arm-chair, a Talairach frame. Prescribed peripheral dose was 25 Gy on the 60%-70% isodose (max dose 100%). Arteriographic results were reassessed in December 1997 at 48 to 96 months follow-up. RESULTS: The overall obliteration rate (OR) was 64% (108/169). AVM volumes ranged from 280 to 19,920 mm(3), median 2460 mm(3). OR was 70% for AVM