Evoked response activity eigenmode analysis in a convoluted cortex via neural field theory.

Neural field theory of the corticothalamic system is used to explore evoked response potentials (ERPs) caused by spatially localized impulse stimuli on the convoluted cortex and on a spherical cortex. Eigenfunctions are calculated analytically on the spherical cortex and numerically on the convoluted cortex via eigenfunction expansions. Eigenmodes on a convoluted cortex are similar to those of the spherical cortex, and a few such modes are found to be sufficient to reproduce the main ERP features. It is found that the ERP peak is stronger in spherical cortex than convoluted cortex, but in both cases the peak decreases monotonically with increasing distance from the stimulus point. In the convoluted case, cortical folding causes ERPs to differ between locations at the same distance from the stimulus point and spherical symmetries are only approximately preserved.

Neural field theory of perceptual echo and implications for estimating brain connectivity.

Neural field theory is used to predict and analyze the phenomenon of perceptual echo in which random input stimuli at one location are correlated with electroencephalographic responses at other locations. It is shown that this echo correlation (EC) yields an estimate of the transfer function from the stimulated point to other locations. Modal analysis then explains the observed spatiotemporal structure of visually driven EC and the dominance of the alpha frequency; two eigenmodes of similar amplitude dominate the response, leading to temporal beating and a line of low correlation that runs from the crown of the head toward the ears. These effects result from mode splitting and symmetry breaking caused by interhemispheric coupling and cortical folding. It is shown how eigenmodes obtained from functional magnetic resonance imaging experiments can be combined with temporal dynamics from EC or other evoked responses to estimate the spatiotemporal transfer function between any two points and hence their effective connectivity.

Predictors of disease-free survival in colorectal cancer with microsatellite instability: An AGEO multicentre study.

BACKGROUND: A microsatellite instability (MSI) phenotype is found in about 12% of colorectal cancers (CRCs) and is associated with a low recurrence rate after curative surgery. Several studies have identified clinical and pathological factors predictive of recurrence in resected CRC, but not in the MSI subgroup. PATIENTS AND METHODS: This multicentre retrospective study included patients with stage I, II or III MSI CRCs. Disease-free survival (DFS) was calculated with the Kaplan-Meier method. Factors associated with DFS were identified in univariate and multivariate Cox analyses. RESULTS: We studied 521 patients with MSI CRC. Respectively 11%, 51% and 38% of patients were at stage I, II and III. Mean age was 68.7years and 36% of the patients received adjuvant chemotherapy. Median follow-up was 32.8months. The disease recurrence rates were 6% and 21% in stage II and III patients, respectively. The 3-year DFS rate was 77%. In univariate analysis, age, bowel obstruction, lymph node invasion, stage T4, vascular emboli, lymphatic invasion and perinervous invasion were associated with poorer DFS (P<0.05). Three relevant independent predictors of poor DFS were identified in multivariate analysis, namely bowel obstruction (HR=2.46; 95%CI 1.31-4.62, P=0.005), vascular emboli (HR=2.79; 95%CI 1.74-4.47, P<0.001) and stage T4 (HR=2.16; 95%CI 1.31-3.56, P=0.002). CONCLUSIONS: Bowel obstruction, vascular emboli and stage T4 are independently associated with MSI CRC recurrence, suggesting that screening for vascular emboli in routine clinical practice may assist with adjuvant chemotherapy decision-making.

Effect of low-frequency KRAS mutations on the response to anti-EGFR therapy in metastatic colorectal cancer.

BACKGROUND: Only patients with wild-type (WT) KRAS tumors benefit from anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (Mabs) in metastatic colorectal cancer (mCRC). Pyrosequencing is now widely used for the determination of KRAS mutation burden and a conservative cut-off point of 10% has been defined. Up until now, the impact of low-frequency KRAS mutations (<10%) on the response to anti-EGFR Mabs has yet to be evaluated. PATIENTS AND METHODS: Tumors from patients receiving anti-EGFR Mabs based on a WT genotype for KRAS, as determined using direct sequencing, have been retrospectively analyzed by pyrosequencing. Patients were categorized as WT (no KRAS mutation) or low-frequency mutation when KRAS mutation was <10% (KRAS low MT). RESULTS: A total of 168 patients treated by anti-EGFR Mabs for mCRC were analyzed. According to pyrosequencing, 138 tumors remained KRAS WT, while 30 tumors were KRAS low MT. In the KRAS low MT and KRAS WT groups, the response rates were 6.7% and 37.0%, respectively, while stabilization amounted to 23.3% versus 32.6% and progression to 70% versus 29% (P < 0.01). Progression-free survival (PFS) was 2.7 ± 0.5 months for KRAS low MT and was 6.0 ± 0.3 months for KRAS WT (P < 0.01). CONCLUSIONS: These results appear to validate consideration of low-frequency KRAS mutation tumors as positive, and justify a large-scale prospective study.

[Improvement of carbohydrate deficient transferrin measurement by capillary zone electrophoresis using immunosubtraction of immunoglobulins and transferrin]. / Intérêt de l'immunosoustraction des immunoglobulines et de la transferrine dans le dosage de la transferrine désialylée en électrophorèse capillaire.

CDT (Carbohydrate Deficient Transferrin) is considered as the most efficient biomarker of alcohol abuse available for routine use. Among the various methods developed for its measurement, capillary zone electrophoresis (CZE) on the multicapillary analyzer Capillarys2 provides high quality results at high throughput. However, the non CDT specific measurement of protein absorbance at 200 nm may bring abnormal profiles in samples from patients with high polyclonal immunoglobulin level or monoclonal component. We evaluated the automated immunosubtraction procedure developed by the manufacturer in 48 samples with abnormal electrophoretic profiles that potentially could interfere with CZE measurement of CDT. Elimination of the serum immunoglobulins raised the number of interpretable profiles from 19 (40%) to 37 (77%). The immunosubtraction procedure failed in samples with a monoclonal component present at a concentration > 60 g/L and in some samples harbouring a partially degraded C3 fraction. Six samples identified as genetic BC transferrin variants were also included in the study and submitted to an automated transferrin subtraction procedure to ascertain whether the additional peak were actually transferrin glycoforms. After treatment, two samples were classified as homozygote C for transferrin due to the persistence of one of the supposed transferrin peak. In conclusion, immunoglobulin and transferrin subtraction allow a better CDT measurement in most samples with interfering monoclonal components and avoid misclassification of suspected transferrin BC or CD variants.

[Lentiviral vectors]. / Lentivecteur: l'anti-vecteur rétroviral ?

The recent advent of RNA interference has strongly stimulated the growing interest toward lentiviral vectors. This, plus the occurrence of several adverse effects in a clinical trial in which oncoretroviral vectors were employed, refocused the need for efficient tools allowing a stable in vivo gene transfer. The lentivectors were first developed in 1996 to address the poor efficiency of murine retroviral vectors to transduce arrested cells. Taking advantage of the accumulated experience in retroviral vector design, a rapid evolution of the structural form of the lentivectors converted this gene transfer agent into a very simple and popular tool. This rapidly led to several commercially available solutions. In the present review, more than a simple comparison to oncoretroviral vectors, we aimed at emphasizing the specific points that distinguish lentiviral vectors and confirm them as good and safe candidates for the clinical delivery of therapeutic genes.

[Alphavirus derived vector, still a relevant system through new mobilisation procedure]. / Les vecteurs dérivés des alphavirus, un système toujours pertinent grâce à de nouveaux modes de vectorisation.

Among eukaryotic cell-expression-systems, the one derived from alphaviruses, including Semliki forest virus (SFV), offers an efficient method for protein production in mammalian cells. Despite this efficacy, twenty years after their discovery alphaviruses vectors remain poorly used. Alphavirus vectors exist as naked RNA vectors or as recombinant particles. The use of costly RNA-based replicons, and the fact that production of recombinant particles is a complex process to carry out, have hampered the attractiveness of the methods. Lastly, the apoptotic signals induced by alphavirus vectors replication leads to a rapid death of the producing cells. This feature, which can be detrimental in vitro, is advantageously exploited for in vivo applications. Besides laboratory applications, alphavirus vectors have been explored in rare phase I clinical trials, for vaccine development and cancer gene therapy, therefore, alphavirus vector will benefit from the advent of new, biosafety-efficient, methods for particles production. Most of the recent advances in the field proposed an heterologous mobilisation of alphavirus replicon. While increasing biosafety aspects, new methods are also simpler regarding the genesis of recombinant particles. In the present review, we overview the alphavirus life cycle with a special attention to the features influencing vector design and utility.

[An anicteric cholectasis and nephrotic syndrome: AL amyloïdosis in a 51 years-old man]. / Une cholestase anictérique associée à un syndrome néphrotique chez un homme de 51 ans: découverte d'une amylose AL.

Amyloidosis is a multiple-organ disease for which the diagnosis is often confusing and thereby delayed. Here, we present an archetypal case illustrating such difficulties. A 51 years-old man presented a mixed dyslipemia in November 2002, in June 2004 he has finally been diagnosed with a primary AL-amyloidosis. Within these two years, the arising of a non-icteric cholestasis and a nephrotic syndrome have triggered the search for a disease related to a multiple-organ protein deposition. Confirmation of the AL-amyloidosis was obtained through an histological examination, including direct immuno-fluorescence. Amyloidosis is a life threatening disease that need to be diagnosed at an early stage, in order to maximise the therapeutic expectations. The average survival after the diagnosis of AL-amyloidosis is 5% at 10 years. Often, treatments are initiated late in the course of the disease, at a time when organ lesion are constituted, severely affecting the prognosis.

Semliki Forest virus-derived virus-like particles: characterization of their production and transduction pathways.

A procedure for the mobilization of Semliki Forest virus (SFV)-derived replicons using virus-like particles (VLPs) has been recently proposed. VLPs were obtained from 293T cells co-expressing the vesicular stomatitis virus glycoprotein (VSV-G) and a modified SFV replicon. Advantages of SFV VLPs include improved safety with a lack of sequence homology between components and reducing the risk of recombination events that could lead to the formation of autonomous particles. Characterization of SFV VLPs reveals a discrepancy in their ability to infect cells reported to be permissive. Furthermore, it was noted that not all viral envelopes were able to promote VLP release equally from transfected cells. These observations encouraged the examination of the molecular mechanisms supporting the different steps of VLP assembly and transduction. The use of a VSV-G related pathway for VLP entry into target cells was demonstrated; it was also observed that an internal ribosome entry site may not be adapted to control transgene expression in all cells. Finally, the need for a membrane-binding domain to obtain a fully active SFV replication complex and VLP formation was documented.

Cellular factors influencing Semliki Forest Virus vector biology.

Viral vectors are currently the best tools for gene delivery in a therapeutic setting, especially for in vivo use. Alphaviruses, a family of positive singlestranded RNA viruses, have been engineered to allow the formation of a highly efficient replicon. Using these replicons, it is possible to generate recombinant particles. Parental viruses and recombinant vectors share certain pathways while interacting with their target cells. In this review, we describe the consecutive events leading to transduction, and transgene expression, in view of the cellular factors that affect each individual step. Classical virology will benefit from the knowledge accumulated studying vectors, and such work will shed light on crosstalk between intruding viruses and their hosts. Ultimately, these data should help the design of vectors adapted to specific target cells.

Toolbox for retrovectorologists.

Retroviral vectors have actively contributed to the advent of gene therapy as a realistic approach in human therapeutics. At the beginning, the use of retroviral vectors was thought to be as simple as the collection of a viral supernatant that was applied to the desired cell. Rapidly, target resistance to transduction appeared in various conditions, ex vivo as well as in vivo. At that time, retrovectorologists entered an active "back to the bench" era. This phase was thought to have reached its conclusion with the generation of theoretically safe lentiviral vectors and when, in 2000, a first clinical trial using retroviral vectors proved to be successful. Unfortunately, recent developments have shown that we still need to improve our knowledge of several steps in the retroviral life cycle before we can accurately adapt vectors to target specific cells. In this review we will first briefly detail key features of the life cycle of wild-type retroviruses. Thereafter, an overview of the minimal requirements needed to generate retroviral vectors will be followed by the relevant developments in this rapidly moving field. Of note, we have highlighted the crucial biosafety issues in a specific section.

[Adenocarcinomas of the ethmoid sinuses. Epidemiological data]. / Les adénocarcinomes de l'ethmoïde.

OBJECTIVE: The relationship between adenocarcinomas of the ethmoid (ADKE) and wood-dust exposure has been well established. Sino-nasal cancer in wood-workers has been added to the list of occupational disorders in France, as prescribed disease number 47-Bq. PATIENTS AND METHODS: Our data set consisted of 207 cases with sino-nasal cancer (from January 1985 to January 2001). Among these cases, 67.1% were adenocarcinoma. A wood dust exposure has been reported in 96.4% cases. The mean duration of wood dust exposure was 30 years. The mean latency between the end of the exposure and the diagnostic was 10.6 years. RESULTS: Our epidemiological data confirmed those from the biomedical literature. The occupations at greatest risk are furniture workers, sawmill workers, carpentry workers, and other wood product workers. Two components of exposure - duration and average level - contributed independently to the overall elevated risk. The risk is greater among men who were employed in jobs with the highest wood dust exposure and increases with the duration of exposure. CONCLUSIONS: The preinvasive stages of ADKE (mucostasis/cuboïd metaplasia/dysplasia) are still an unverified hypothesis. ADKE were observed in workers who use "hard" woods. The chemical nature of the carcinogenic factor(s) in wood dust is not known. The factors responsible for induction of ADKE in hard wood-workers probably exist in the wood-dust itself. Tannins were suggested as possible contributing agents to induction of ADKE. In addition to wood dust, exposures may include formaldehyde. Given these facts, it should be possible to define preventive measures, so that incidence of ADKE in professional wood and leather workers should decrease.

[Drainage after thyroid surgery: 264 patients]. / Drainage dans la chirurgie thyroïdienne.

OBJECTIVES: A prospective study was conducted in 1996-1997 in 100 patients who underwent thyroid surgery and who were randomly assigned to receive drainage or not. No statistical difference in complication rate was observed. The aim of the present retrospective study was to assess the consequences of this attitude in patients undergoing surgery since that time and to determine the number of postoperative complications, length of hospital stay, and type of thyroidectomy where cervical drains still appear to be indicated. PATIENTS AND METHODS: Total or partial thyroid surgery was performed in 264 patients between June 1997 and October 2000. Neck dissection was associated with 24 patients. RESULTS: Cervical drains were used in 29 patients (10.9%). Postoperative complications were comparable to those commonly reported. CONCLUSION: Except for neck dissection and mediastinal extension, thyroidectomy can be safely performed without drainage. This attitude reduces the overall hospital stay.

A prospective, multicentre study of moxifloxacin concentrations in the sinus mucosa tissue of patients undergoing elective surgery of the sinus.

A pharmacokinetic study was carried out to determine moxifloxacin concentrations in sinus tissue, after oral moxifloxacin 400 mg once daily for 5 days to patients with chronic sinusitis, undergoing elective sinus surgery. Patients were randomly allocated to one of seven treatment groups, in which tissues were sampled 2, 3, 4, 6, 12, 24 or 36 h post-dose. A control group with non-infected nasal polyps was also included. Forty-eight patients (13 female, 35 male, mean age 47.1 years) were allocated to one of each active treatment group (n = 42) or to the control group (n = 6). Tissue and plasma samples were taken simultaneously and stored frozen until assayed by HPLC. Thirty-nine patients were fully valid for pharmacokinetic analysis. The geometric mean moxifloxacin plasma concentration increased from 2.32 mg/L at 2 h to a maximum of 3.37 mg/L at 4 h post-dose, decreasing to 0.37 mg/L at 36 h post-dose. The moxifloxacin concentration in sinus mucosa was consistently greater than that in plasma being 4.56-5.73 mg/kg from 2 to 6 h and 2.81-1.25 mg/kg from 12 to 36 h post-dose. The elimination rates in plasma and sinus tissues were similar. The tissue/plasma ratio was c. 200% between 2 and 6 h, and up to 328.9% at 36 h. Results were similar whatever the site of tissue sampling (maxillary sinus, anterior ethmoid sinus or nasal polyps). Tissue levels exceeded the MIC(90) of all pathogens commonly causing acute sinusitis (e.g. 5-30 x MIC for Streptococcus pneumoniae: 0.25 mg/L). These results sup-port the use of moxifloxacin 400 mg once daily as a regimen for the treatment of sinus infections.

Carbohydrate-deficient transferrin (CDT) determination by nephelometry using a commercial kit. Analytical and diagnostic aspects.

Carbohydrate-deficient transferrin (CDT) has been proposed as the most efficient marker of alcohol abuse. Absolute and relative concentrations of CDT were measured with a commercial assay (%CDTTIA from AXIS-Shield, Oslo, Norway) using rate nephelometry for transferrin determination. One hundred eighty-eight alcoholic patients (154 males, 34 females) and 132 control patients (113 males, 19 females) were included in the study. Within-run and day-to-day imprecision were 3.15% and 9.77%, respectively. The calibration curve was stable for more than 4 months with a shift below 5%. The commercial assay lacked sensitivity (Se = 0.48), but was highly specific (Sp = 0.98). Lowering the cut-off from 6% to 4.6% raised the sensitivity of the %CDTTIA test to 0.76 with a specificity of 0.90. We conclude that this adaptation to the Array Protein System (Beckman-Coulter) is suitable for routine use and offers precise results. It, however, requires an adaptation of the cut-off value for patients and of the target value for kit controls.

Efficient DNA transfection mediated by the C-terminal domain of human immunodeficiency virus type 1 viral protein R.

Viral protein R (Vpr) of human immunodeficiency virus type 1 is produced late in the virus life cycle and is assembled into the virion through binding to the Gag protein. It is known to play a significant role early in the viral life cycle by facilitating the nuclear import of the preintegration complex in nondividing cells. Vpr is also able to interact with nucleic acids, and we show here that it induces condensation of plasmid DNA. We have explored the possibility of using these properties in DNA transfection experiments. We report that the C-terminal half of the protein (Vpr(52-96)) mediates DNA transfection in a variety of human and nonhuman cell lines with efficiencies comparable to those of the best-known transfection agents. Compared with polylysine, a standard polycationic transfection reagent, Vpr(52-96) was 10- to 1,000-fold more active. Vpr(52-96)-DNA complexes were able to reach the cell nucleus through a pH-independent mechanism. These observations possibly identify an alternate pathway for DNA transfection.

[Principles of physics and application of the laser in plastic surgery]. / Principes physiques et application du laser en chirurgie esthétique.

Recent advances in laser technology have expanded the surgeon's possibilities to treat various cutaneous lesions, as well as proposing a new tool for skin rejuvenation. Review of the basic physical principles of laser energy then overview of the different lasers used in plastic surgery as well as some of their clinical applications.

LPS challenge in D-galactosamine-sensitized mice accounts for caspase-dependent fulminant hepatitis, not for septic shock.

Experimental models of sepsis using endotoxin challenges, including studies with sensitized animals with D-galactosamine, have largely contributed to the basic rationale for innovative clinical trials in human septic shock, which have, to date, failed. The ability of these models to reproduce human disease has been highly discussed. We report here that the widely used D-galactosamine/LPS model does not account for septic shock. Treatment with YVAD-CMK, a potent tetrapeptide inhibitor of caspases of the interleukin (IL)-1beta converting enzyme (ICE) family, protects from LPS-induced liver apoptosis and mortality in D-galactosamine-sensitized mice when administered either before or up to 2 h after the lethal challenge. This curative effect is related to complete inhibition of caspase-3 activity in the liver. However, YVAD-CMK does not affect LPS-induced release of IL-1beta and does not protect from a lethal dose of LPS in unsensitized mice. These experiments demonstrate the difference between these two widely recognized experimental models of sepsis. LPS toxicity in D-galactosamine-treated mice, leading to blocked gene transcription, results from tumor necrosis factor (TNF)-alpha-induced caspase-3-dependent liver injury, not from the systemic inflammatory response. These results provide evidence that inhibitors of the ICE caspase family can prevent or even overcome the ongoing hepatic injury induced by TNF-alpha during sepsis, ischemia-reperfusion, or severe hepatitis.