Two phase-matching regimes in high-order harmonic generation.

High-order harmonic generation (HHG) provides scalable sources of coherent extreme ultraviolet radiation with pulse duration down to the attosecond time scale. Efficient HHG requires the constructive interplay between microscopic and macroscopic effects in the generation volume, which can be achieved over a large range of experimental parameters from the driving field properties to those of the generating medium. Here, we present a systematic study of the harmonic yield as a function of gas pressure and medium length. Two regimes for optimum yield are identified, supporting the predictions of a recently proposed analytical model. Our observations are independent on the focusing geometry and, to a large extent, on the pulse duration and laser intensity, providing a versatile approach to HHG optimization.

Right colectomy: value of the totally laparoscopic approach.

UNLABELLED: The role of laparoscopy for right colectomy remains controversial - largely because of a lack of standardization of the operative procedure, including a diversity of techniques including laparoscopy-assisted cases with extra-corporeal anastomosis and totally laparoscopic procedures with intra-corporeal anastomosis. METHODS: The charts of all patients who underwent right colectomy by a totally laparoscopic approach in our service since 2004 were reviewed and pre-, intra-, and postoperative data were collected. RESULTS: Eighty-two patients underwent totally laparoscopic right colectomy; of these, 32 had a BMI greater than 20 kg/m2 (39%). The mean operative duration was 113 minutes. In most cases, the operative specimen was extracted through a supra-pubic Pfannenstiel incision measuring 4-6 cm in length. Three cases were converted to a laparoscopy-assisted technique (in order to control the ileo-cecal vascular pedicle because of extensive nodal invasion in two cases, and to evaluate a hepatic flexure polyp in the third case). Overall morbidity was 29.3% and parietal morbidity was only 9.8%; there was no difference in morbidity between obese patients (BMI>30 kg/m2) and non-obese patients (BMI<30 kg/m2). The mean duration of hospitalization was 9 days and two patients developed ventral hernia in the extraction incision in long-term follow-up. CONCLUSION: These satisfactory results show that the totally laparoscopic approach to right colectomy is technically feasible and safe, even in obese patients. In addition, the very low rate of parietal complications is an argument in favor of this approach.

Management of acute diverticulitis in a tertiary care institution.

BACKGROUND: Diverticular disease of the left colon is a common disease, mainly in the population over 50 years of age. The surgical management of acute diverticulitis is remains controversial, especially in severe forms. OBJECTIVE: This study aimed to evaluate the results of laparoscopic surgery for diverticular disease in a tertiary care institution with a specialist interest in minimally invasive surgery. DESIGN: All patients who had elective laparoscopic sigmoidectomy for diverticulitis within eight years at University Hospital of Luxembourg were selected from a retrospective database to evaluate laparoscopic benefit in moderate and severe disease. RESULTS: A total of 155 patients were divided in two groups: Moderate Acute Diverticulitis (MAD) and Severe Acute Diverticulitis (SAD) respectively. The short-term outcomes, after laparoscopic sigmoidectomy, were evaluated. There were not important differences between two groups. CONCLUSIONS: The laparoscopic management of diverticular disease after moderate and severe crisis gives same benefits and short-term outcomes are similar. Elective Laparoscopic surgery is actually the standard of care for moderate and severe diverticular disease in our institution.

Influence of obesity-susceptibility loci (MC4R and INSIG2) on the outcome of weight loss and amelioration of co-morbidity in obese patients treated by a gastric-bypass.

BACKGROUND: Genome-wide association and linkage studies have identified multiple susceptibility loci for obesity. OBJECTIVE: We hypothesized that such loci may affect weight loss and comorbidity amelioration outcomes following a gastric-bypass. DESIGN: A total of 200 obese patients who underwent a gastric bypass surgery were genotyped for single-nucleotide polymorphisms (SNPs) in insulin induced gene 2 (INSIG2) and melanocortin 4 receptor (MC4R) obesity genes. RESULTS: After a follow-up of 18 month, the patients (192) data of weight excess loss (72%) and co-morbidities (Hypertension -62- and Diabetes -39-) were analyzed and compared. 26 Patients with SNP were found (9 MC4R and 17 INSIG2). No significant differences in weight excess loss and amelioration of comorbidities were revealed. CONCLUSIONS: The data suggest no influence of weight excess loss and amelioration of co-morbidities after gastric-bypass by genetic susceptibility.

Comparison of seven staining methods for senile plaques and neurofibrillary tangles in a prospective series of 15 elderly patients.

Samples of brain from 15 prospectively tested women over 75 years of age, living in the same institution and with a Blessed test score between 0 and 28 were studied to evaluate seven different staining techniques for counting senile plaques and neurofibrillary tangles. The methods included Bielschowsky (modified by Yamamoto & Hirano, 1986), Cross, Gallyas, Naoumenko-Feigin, silver methenamine, Bodian coupled with luxol fast blue, and thioflavine S; these techniques were performed on contiguous slides of the first temporal gyrus (Brodmann's area 22). The cost, difficulty and variability of the methods were evaluated. Modified Bielschowsky method revealed both amyloid and neurites. Cross, Bodian and Gallyas stained neurites preferentially and were more sensitive for neurofibrillary tangles than for senile plaques. Silver methenamine revealed amyloid in much the same way as thioflavine S. The highest count of senile plaques and neurofibrillary tangles was obtained with the modified Bielschowsky method. Best correlations between density of senile plaques and Blessed test score were obtained with modified Bielschowsky impregnation, silver methenamine, and Bodian and those for neurofibrillary tangles, with modified Bielschowsky, Naoumenko-Feigin, and Gallyas methods. Naoumenko-Feigin impregnation, even if fitted to the linear model, revealed very few changes (four times less than modified Bielschowsky) and appeared to be insensitive. All the techniques except Naoumenko-Feigin, were equally able to distinguish two groups of cases, i.e. those affected by Alzheimer's disease and those not affected. A multiple regression analysis indicated that the statistical relationship between the density of changes, evaluated after the modified Bielschowsky method, and the Blessed test score could not be improved by the additional use of other staining techniques. These data have direct implications for the evaluation of diagnostic criteria in Alzheimer's dementia. In this study, modified Bielschowsky impregnation was found to give the most complete picture of the lesions and, as such, could be considered a reference method. This technique is, however, expensive and difficult to perform. It stains a large number of normal structures and the recognition of the lesions is more subjective than with other selective stains. It is therefore difficult to recommend this technique for routine use. Other techniques alone, or in combination, can be recommended but the diagnostic criteria should be adapted for each of them.

Tau, paired helical filaments and amyloid in the neocortex: a morphometric study of 15 cases with graded intellectual status in aging and senile dementia of Alzheimer type.

Tau immunoreactivity was studied in temporal neocortex, area 22, in 15 cases with graded intellectual status and compared with the immunoreactivity observed with an antiserum against paired helical filaments (PHF) and with the density of amyloid revealed by thioflavin S. Samples came from women over 75 years either intellectually normal or affected by senile dementia of the Alzheimer type at various degrees of severity. Mental status had been prospectively assessed by the Blessed's test score. Anti-tau labelled a neuropil meshwork, the density of which increased with the severity of the disease. This meshwork was denser in layers II, III and V in the most affected cases. The number and the size of the tau-positive fibers within the senile plaques increased with the intellectual deficit. Senile plaques were more numerous in layers II and III and neurofibrillary tangles in layers III and V whatever the staining technique: tau or PHF immunocytochemistry, and thioflavin S. The densities of senile plaques and of neurofibrillary tangles (NFT) were correlated with the severity of the disease whatever the staining method. The three methods revealed a systematically different number of changes. This systematic difference could greatly influence the neuropathological diagnosis. It could be the consequence of various factors: different sensitivities of the staining methods or changes in the antigenic and amyloid composition of the lesion according to the stage of the disease. In line with the last hypothesis, a higher proportion of amyloid-rich plaques was noted in the less affected cases, suggesting that tau and PHF epitopes appeared secondarily.(ABSTRACT TRUNCATED AT 250 WORDS)

Does amyloid precede paired helical filaments in the senile plaque? A study of 15 cases with graded intellectual status in aging and Alzheimer disease.

The density of senile plaques in 15 women over 75 years of age was higher when evaluated by thioflavine S than by immunocytochemistry with a polyclonal antibody against paired helical filaments. Mental status had been prospectively assessed in this cohort by the test score of Blessed et al. A difference between the two methods was found whatever the degree of mental impairment. Senile plaques were exceptionally immunolabeled in the least affected cases. This could not be explained only by differences in sensitivity of the stains and suggests that the amyloid is surrounded by anti-PHF positive neurites only in the latest stages of the senile plaque.

Use of alveolar macrophages in antianoxic drug studies.

Alveolar macrophages are able to adapt their energy metabolism to very difficult survival conditions. Gaseous phase culture is adaptable to alveolar macrophages because it reproduces in vitro conditions very similar to in vivo conditions. It is easy to modify the incubation gas composition for hypoxia and anaerobiosis. Metabolic changes and cell injury were evaluated in three studies carried out after 24 hr of gaseous phase culture in normoxia and in anaerobiosis with a possible treatment with 0.01 microgram/ml vincamine: 1) ATP content assay by bioluminescence, the witness of cell vitality which decreases significantly in anaerobiosis; 2) Lactate assay which shows the metabolism derivation towards the anaerobic pathways; and 3) Tritiated deoxyglucose (DOG) incorporation, which shows glucose requirements after hypoxic incubation, maintaining or recovering a certain level of energetic activity. This incorporation greatly increases after anaerobic culture. Vincamine has no activity in normoxia. The three parameters are not significantly different from control, but in anaerobiosis, vincamine reveals an interesting protective effect. ATP content decreases under treatment and DOG incorporation increases. This demonstrates that vincamine is able to maintain cell metabolic activity for a longer period of time after the beginning of hypoxic trial. Cells can better use their energy storage and the metabolic pathways which enable them to restore themselves, thanks to vincamine treatment. It has been shown that cell membrane integrity was preserved by tests using cytochalasin B. DOG was not incorporated by cells treated with cytochalasin B after 24 hr of anaerobic culture and normally incorporated by control cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Cortical atrophy in senile dementia of the Alzheimer type is mainly due to a decrease in cortical length.

A prospective study was undertaken to select mentally normal old subjects and patients with senile dementia of the Alzheimer type (SDAT). The test score of Blessed et al. (1968) (BTS) was used to determine the severity of mental impairment. A pathologic study confirmed the diagnosis of either SDAT or normal brain aging at postmortem examination in 12 cases. The cortical area and the cortical perimeter of the different cerebral lobes were measured on 1-cm-thick coronal sections using a semiautomatic image analyzer. Cortical length and thickness were calculated using perimeter and area values. BTS was significantly correlated with both the area (r = 0.7695, P = 0.003) and the length (r = 0.7421, P = 0.006) of the temporal cortex. There was no significant correlation between BTS and thickness of the temporal cortex (r = 0.559, P = 0.059). These results show that reduction of length is one of the major determinants of cortical atrophy. Although this has to be confirmed by histological study, they favor the hypothesis of a column-selective atrophy in SDAT which should be considered in the interpretation of the microscopic data.