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Biomedical subjects

S Collin

Publications and source records attributed to S Collin.

At least 19 recordsLinked to original sources
PubMed2006

Preoperative chemotherapy for resectable thoracic esophageal cancer.

BACKGROUND: Surgery has been the treatment of choice for localized esophageal cancer. A number of studies have investigated whether preoperative chemotherapy followed by surgery leads to an improvement in cure rates but the individual reports have been conflicting. An explicit systematic update of the role of preoperative chemotherapy in the treatment of resectable thoracic esophageal cancer is, therefore, warranted. OBJECTIVES: The objective of this review is to determine the role of preoperative chemotherapy on patients with resectable thoracic esophageal carcinomas. SEARCH STRATEGY: Trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1966 to 2006), EMBASE (1988 to 2006) and CANCERLIT (1993 to 2002). There were no language restrictions. SELECTION CRITERIA: All trials of patients with potentially resectable carcinomas of the esophagus (of any histologic type) who were randomised to having either chemotherapy or no chemotherapy before surgery. DATA COLLECTION AND ANALYSIS: The primary outcome was survival, which was assessed using hazard ratios. This is an amendment to the original review which used relative risks to assess survival at yearly intervals. Hazard ratios (HR) have now been introduced to summarise the complete survival experience in a single analysis. The risk ratio (relative risk; RR) was used to compare rates of resections, tumour recurrences and treatment morbidity and mortality. MAIN RESULTS: There were eleven randomised trials involving 2019 patients. Eight trials (1729 patients) reported sufficient detail on survival to be included in a meta-analysis for the primary outcome. There was some evidence to suggest that preoperative chemotherapy improves survival, but this was inconclusive (HR 0.88; 95% CI 0.75 to 1.04). There was no evidence to suggest that the overall rate of resections (RR 0.96, 95% CI 0.92 to 1.01) or the rate of complete resections (R0) (RR 1.05; 95% CI 0.97 to 1.15) differ between the preoperative chemotherapy arm and surgery alone. There is no evidence that tumour recurrence (RR 0.81, 95% CI 0.54 to 1.22) or non-fatal complication rates (RR 0.90; 95% CI 0.76 to 1.06) differ for preoperative chemotherapy compared to surgery alone. Trials reported risks of toxicity with chemotherapy that ranged from 11% to 90%. AUTHORS' CONCLUSIONS: In summary, preoperative chemotherapy plus surgery may offer a survival advantage compared to surgery alone for resectable thoracic esophageal cancer, but the evidence is inconclusive. There is some evidence of toxicity and preoperative mortality associated with chemotherapy.

Antineoplastic Agents↗
PubMed2006

Occurrence of polyfunctional thiols in fresh lager beers.

Polyfunctional thiols are known to have a strong impact on the overall aroma of many fermented foods. Surprisingly, very little data is available on their occurrence in beer. A specific extraction with p-hydroxymercuribenzoic acid was performed on four different fresh light-protected lager beers. gas chromatography-olfactometry, gas chromatography-mass spectrometry, and gas chromatography-pulsed-flame photometer detector analyses of the extracts revealed the presence of more than 10 polyfunctional thiols. All of them were absent from wort, suggesting a key role of the H(2)S excreted by yeasts. 3-Methyl-2-buten-1-thiol, 2-mercapto-3-methylbutanol, 3-mercapto-3-methylbutanol seem to be created from hop allylic alcohols via four different mechanisms: nucleophilic substitution, addition-elimination, and radical anti-Markovnikov or electrophilic Markovnikov additions. 1,4 Addition of hydrogen sulfide to wort alpha,beta-unsaturated aldehydes or ketones may explain the synthesis of 1-mercapto-3-pentanol, 3-mercaptohexanol, and 4-mercapto-4-methyl-2-pentanone through fermentation. Finally, 2-mercaptoethanol, 3-mercaptopropanol, and their corresponding acetates may derive from Ehrlich degradation of sulfur amino acids, while 2-methyl-3-furanthiol should be logically issued from Maillard reactions.

Beer↗
PubMed2006

Analysing ethnobotanical and fishery-related importance of mangroves of the East-Godavari Delta (Andhra Pradesh, India) for conservation and management purposes.

Mangrove forests, though essentially common and wide-spread, are highly threatened. Local societies along with their knowledge about the mangrove also are endangered, while they are still underrepresented as scientific research topics. With the present study we document local utilization patterns, and perception of ecosystem change. We illustrate how information generated by ethnobiological research can be used to strengthen the management of the ecosystem. This study was conducted in the Godavari mangrove forest located in the East-Godavari District of the state Andhra Pradesh in India, where mangroves have been degrading due to over-exploitation, extensive development of aquaculture, and pollution from rural and urbanized areas (Kakinada).One hundred interviews were carried out among the fisherfolk population present in two mangrove zones in the study area, a wildlife sanctuary with strong conservation status and an adjacent zone. Results from the interviews indicated that Avicennia marina (Forsk.) Vierh., a dominant species in the Godavari mangroves, is used most frequently as firewood and for construction. Multiple products of the mangrove included the bark of Ceriops decandra (Griff.) Ding Hou to dye the fishing nets and improve their durability, the bark of Aegiceras corniculatum (L.) Blanco to poison and catch fish, and the leaves of Avicennia spp. and Excoecaria agallocha L. as fodder for cattle. No medicinal uses of true mangrove species were reported, but there were a few traditional uses for mangrove associates. Utilization patterns varied in the two zones that we investigated, most likely due to differences in their ecology and legal status. The findings are discussed in relation with the demographic and socio-economic traits of the fisherfolk communities of the Godavari mangroves and indicate a clear dependency of their livelihood on the mangrove forest.Reported changes in the Godavari mangrove cover also differed in the two zones, with significantly less perceptions of a decrease in the protected area, as compared to the adjacent non-protected area. A posteriori comparisons between sequential satellite imagery (retrospective till 1977) and respondents that were at least 15 years back then, revealed a mangrove decrease which was however perceived to different extents depending on the area with which the fishermen were familiar. While local needs had not been incorporated in the existing policy, we created a framework on how data on ethnobotanical traditions, fishery-related activities and local people's perceptions of change can be incorporated into management strategies.

Adolescent↗
PubMed2005

Probing carrier dynamics in nanostructures by picosecond cathodoluminescence.

Picosecond and femtosecond spectroscopy allow the detailed study of carrier dynamics in nanostructured materials. In such experiments, a laser pulse normally excites several nanostructures at once. However, spectroscopic information may also be acquired using pulses from an electron beam in a modern electron microscope, exploiting a phenomenon called cathodoluminescence. This approach offers several advantages. The multimode imaging capabilities of the electron microscope enable the correlation of optical properties (via cathodoluminescence) with surface morphology (secondary electron mode) at the nanometre scale. The broad energy range of the electrons can excite wide-bandgap materials, such as diamond- or gallium-nitride-based structures that are not easily excited by conventional optical means. But perhaps most intriguingly, the small beam can probe a single selected nanostructure. Here we apply an original time-resolved cathodoluminescence set-up to describe carrier dynamics within single gallium-arsenide-based pyramidal nanostructures with a time resolution of 10 picoseconds and a spatial resolution of 50 nanometres. The behaviour of such charge carriers could be useful for evaluating elementary components in quantum computers, optical quantum gates or single photon sources for quantum cryptography.

Journal Article↗
PubMed2005

Highly directional radiation generated by a tungsten thermal source.

We report the design of a tungsten thermal source with extraordinarily high directivity in the near infrared, comparable to the directivity of a CO2 laser. This high directivity is the signature of the long-range correlation of the electromagnetic field in the source plane. This phenomenon is due to the resonant thermal excitation of surface-plasmon polaritons.

Journal Article↗
PubMed2005

Prevalence and associations of vitamin D deficiency in foreign-born persons with tuberculosis in London.

OBJECTIVES: The incidence of tuberculosis (TB) is high amongst foreign-born persons resident in developed countries. Vitamin D is important in the host defence against TB in vitro and deficiency may be an acquired risk factor for this disease. We aimed to determine the incidence and associations of vitamin D deficiency in TB patients diagnosed at an infectious diseases unit in London, UK. METHODS: Case-note analysis of 210 unselected patients diagnosed with TB who had plasma vitamin D (25(OH)D3) levels routinely measured. Prevalence of 25(OH)D3 deficiency and its relationship to ethnic origin, religion, site of TB, sex, age, duration in the UK, month of 25(OH)D3 estimation and TB diagnosis were determined. RESULTS: Of 210 patients 76% were 25(OH)D3 deficient and 56% had undetectable levels. 70/82 Indian, 24/28 East African Asian, 29/34 Somali, 14/19 Pakistani and Afghani, 16/22 Sri Lankan and 2/6 other African patients were deficient (with 58, 17, 23, 9, 6 and 1 having undetectable levels, respectively). Only 0/6 white Europeans and 1/8 Chinese/South East Asians had low plasma 25(OH)D3 levels. Muslims, Hindus and Sikhs all had equivalent rates of deficiency though Hindus were more likely to have undetectable levels (odds ratio 1.87, 95% CI 1.27-2.76). There was no significant association between 25(OH)D3 level and site of TB or duration of residence in the UK. There was no apparent seasonal variation in either TB diagnosis or 25(OH)D3 level. CONCLUSIONS: 25(OH)D3 deficiency commonly associates with TB among all ethnic groups apart from white Europeans, and Chinese/South East Asians. Our data support a lack of sunlight exposure and potentially a vegetarian diet as contributors to this deficiency.

Case-Control Studies↗
PubMed2005

Implementation of a tight glycaemic control protocol using a web-based insulin dose calculator.

We describe the implementation of a glucose control protocol supported by a web-based insulin dose calculator in a 16-bedded intensive care unit. The protocol was introduced and then modified after 15 months' use. Glucose concentrations were retrospectively reviewed and compared for the 9-month period before introduction of the protocol (288 patients), for 15 months after its introduction (502 patients) and for a further 5 months after its modification to increase insulin dose (101 patients). The mean (SD) blood glucose concentrations decreased from 7.3 (1.8) mmol.l(-1) to 6.6 (1.6) mmol.l(-1) and then to 6.2 (1.3) mmol.l(-1). The proportion of values < 8.0 mmol.l(-1) increased from 69% to 81% and then to 89%. Blood glucose concentrations were increased by the use of intravenous nutrition and by vasoactive drugs but not by the administration of propofol. The odds ratio [95% CI] for death for glucose values > 8.0 mmol.l(-1) was 2.10 [1.19-3.73] compared to values < 6.1 mmol.l(-1). However, patient mortality remained constant during the study. Glycaemic control was improved outside a research setting using a protocol supported by a web-based insulin dose calculator.

Adult↗
PubMed2004

Safe household water treatment and storage using ceramic drip filters: a randomised controlled trial in Bolivia.

A randomised controlled field trial was conducted to evaluate the effectiveness of ceramic drip filters to improve the microbiological quality of drinking water in a low-income community in rural Bolivia. In four rounds of water sampling over five months, 100% of the samples were free of thermotolerant (faecal) coliforms (TTC) compared to an arithmetic mean TTC count of 1517, 406, 167 and 245 among control households which continued to use their customary sources of drinking water. The filter systems produced water that consistently met WHO drinking-water standards despite levels of turbidity that presented a challenge to other low-cost POU treatment methods. The filter systems also demonstrated an ability to maintain the high quality of the treated water against subsequent re-contamination in the home.

Bacteria↗
PubMed2002

Spermine induces precocious development of the spleen in mice.

Spermine is a low molecular weight polyamine involved in the postnatal maturation of the gut. When it is administered orally to suckling rats, it induces maturation of the intestinal tract (liver, pancreas and small intestine). Here we show that this polyamine is able to induce precocious intestinal and splenic development in suckling mice. In fact, in 15-day-old mice which had received spermine orally twice daily for 3 days we observed an increase in the ratio of white pulp surface to total spleen surface in comparison with untreated mice. The two macrophage subsets of the marginal zone and the B-cell population were more developed and reached the development level of 5- or 10-week-old mice. The proliferation rate of B-cells was increased by spermine administration to pups. These observations suggest that spermine might play a role in immune system development; further investigation of its effects are intended, namely the evaluation of its capacity to enhance defence during the neonatal period.

Animals↗
PubMed2002

DNA immunisation. New histochemical and morphometric data.

Splenic germinal center reactions were measured during primary response to a plasmidic DNA intramuscular injection. Cardiotoxin-pretreated Balb/c mice were immunized with DNA plasmids encodmg or not the SAG1 protein, a membrane antigen of Toxoplasma gondii. Specific anti-SAG1 antibodies were detected on days 16 and 36 after injection of coding plasmids. The results of ELISAs showed that the SAG1-specific antibodies are of the IgG2a class. Morphometric analyses were done on serial immunostained cryosections of spleen and draining or non-draining lymph nodes. This new approach made it possible to evaluate the chronological changes induced by DNA immunisation in the germinal centres (in number and in size). Significant increases in the number of germinal centres were measured in the spleen and only in draining lymph nodes after plasmid injection, the measured changes of the germinal centers appeared to result from the adjuvant stimulatory effect of the plasmidic DNA since both the coding and the noncoding plasmid DNA induced them. No measurable changes were recorded in the T-dependent zone of lymph organs.

Animals↗
PubMed2001

Use of GC-olfactometry to identify the hop aromatic compounds in beer.

This paper describes a sensorial aroma extract dilution analysis (AEDA) approach to the analysis of beer aromas derived from hops. To obtain an extract with an odor representative of the original product, the XAD extraction procedure was applied and the experimental conditions were optimized. The aromagrams of three beers were compared: one brewed without hops, one brewed with Saaz hop pellets, and one brewed with Challenger hop pellets. One spicy/hoppy compound, unmodified from hop to beer, proved responsible for the most intense odor in both hopped beer extracts. Another flavoring compound in hops, linalool, also survives through the process to the final beer. Other compounds such as gamma-nonalactone and humuladienone, although not found in our extracts of hop, significantly modify beer aromagrams after hopping. Sulfur compounds characteristic of Challenger hops proved to be at least partially responsible for the unpleasant flavor found in the corresponding beer.

Beer↗
PubMed2001

Combinatorial synthesis and sensorial properties of polyfunctional thiols.

Over the past few years, polyfunctional thiols present as trace components have been found to play a major role in many food flavors, due to their exceptionally low odor thresholds. Unfortunately, their presence in minute concentration (in ng/kg to a few microg/kg) and their high reactivity make it very difficult to extract and identify them. Furthermore, most of them are not yet commercially available. The aim of this work was to characterize the chromatographic and sensorial properties of 10 synthetic mercaptoketones and mercaptoalcohols. Combinatorial chemistry proved to be a very useful way to synthesize them rapidly. Sulfur-selective sulfur chemiluminescence detection chromatograms coupled with mass spectroscopy enabled the target compounds to be identified. Flavor profiles and best estimate gas chromatography lowest amount detected by sniffing (BE-GC-LOADS) values were further determined by GC-olfactometry. As expected, new, exceptionally odorant molecules (BE-GC-LOADS < 0.1 ng) were revealed by this unusual approach.

Chromatography, Gas↗
PubMed2000

Evidence of Strecker aldehyde excretion by yeast in cold contact fermentations.

A medium containing labeled leucine-d(10) has been used to show that Saccharomyces cerevisiae was able to produce deuterated 3-methylbutanal in a cold contact fermentation. Whereas residual unreduced Strecker aldehydes bound to polyphenols were considered until now as the main defect of alcohol-free beers, yeast emerges from this work as an additional source of worty flavor. When the same experiment was conducted without leucine, 3-methylbutanal excretion also occurred, indicating that valine could be used by yeast as precursor.

Aldehydes↗
PubMed2000

Optimized extraction procedure for quantifying norisoprenoids in honey and honey food products.

Norisoprenoids appear as promising compounds for authenticating unifloral honeys. So far, however, no method has been optimized for their isolation from a matrix so rich in sugars. In this framework, an original extraction procedure based on the use of Amberlite XAD-16 was developed. Recovery factors were determined and compared with those obtained with another resin (XAD-2). This was done for different model media and various norisoprenoids. In aqueous or alcoholic solutions, the efficiency of both resins proved very high. As expected, addition of honey decreased the adsorption of nonpolar compounds. This effect was much more pronounced with the lower-porosity XAD-2 support. Sugar addition markedly improved the recovery factors obtained with the XAD-16 resin in the case of more polar norisoprenoids.

Chromatography, Gas↗
PubMed2000

3-methylthiopropionaldehyde as precursor of dimethyl trisulfide in aged beers.

Hop S-methylcysteine sulfoxide has previously been postulated as the precursor of dimethyl trisulfide (DMTS) in beers. The present data point to 3-methylthiopropionaldehyde, the Strecker aldehyde issued from methionine, as another potential precursor in aged beers. Spiking either fresh beer or wort before boiling leads in all cases to higher levels of DMTS after storage. Moreover, special malts with a high level of 3-methylthiopropionaldehyde also favor polysulfide synthesis. A higher pH should increase this onion-like off-flavor, whereas a low pH is unfortunately known to enhance the cardboard flavor of aged beers. 3-methylthiopropanol, issued from yeast reducing activity, can be considered as an additional DMTS source during aging.

Aldehydes↗
PubMed2000

Measuring antioxidant efficiency of wort, malt, and hops against the 2,2'-azobis(2-amidinopropane) dihydrochloride-induced oxidation of an aqueous dispersion of linoleic acid.

This paper presents a simple, convenient method for determining the efficiency of antioxidants in aqueous systems. Production of conjugated diene hydroperoxide by oxidation of linoleic acid in an aqueous dispersion is monitored at 234 nm. 2, 2'-Azobis(2-amidinopropane) dihydrochloride is used as a free radical initiator. Among 12 antioxidants tested, phenolic compounds proved to be the most efficient, both kinetically and in terms of the inhibition time (T(inh)). Applied to wort, malt, and hops, the method confirmed a significant antioxidant activity in such products, especially hops. This assay can be used to follow oxidative changes throughout the brewing process and to understand the contribution of each raw material.

Amidines↗
PubMed1999

Contribution of 3-methylthiopropionaldehyde to the worty flavor of alcohol-free beers.

Alcohol-free beers are usually criticized for two major defects: a lack of fruity aroma and a strong worty flavor. 3-Methylbutanal and 2-methylbutanal are described in the literature as being predominantly responsible for the worty taste. Although detected in large amounts in most malt and wort extracts, both compounds have proven unable to confer worty taste to beers. In this work, we extracted volatiles from wort with a Likens-Nickerson microextractor. The resulting extract had a strong worty aroma. Following GC/MS and GC/olfactometry analysis, 3-methylthiopropionaldehyde turned out to be the key feature since it remained the most organoleptically active compound through extract dilution. In vitro assays showed that 3-methylthiopropionaldehyde is a substrate for several Saccharomyces cerevisiae reducing enzymes. Screening of various strains led us to conclude that the higher the 3-methylbutanal reductase activity, the higher the 3-methylthiopropionaldehyde reductase activity. Monitoring of 3-methylthiopropionaldehyde concentration through an in vivo cold contact process has also been undertaken.

Aldehydes↗