Mechanism of tetralin ring opening and contraction over bifunctional Ir/SiO₂-Al₂O₃ Catalysts

The development of cleaner fuels from conventional resources requires the finding of new hydrotreatment processes able to improve the combustion performances of fuels and limit undesirable emissions. In the context of gas oil upgrading by selective ring opening, we have investigated the hydroconversion of tetralin over iridium nanoparticles supported on amorphous silica-alumina. The conversion of tetralin leads to hydrogenation, ring-contraction, and ring-opening products. The selectivity to ring-opening/-contraction products (ROCPs) increases linearly with the acid-metal site ratio and can be tuned by modifying the metal loading, the metal nanoparticle size, or the support composition. From the combination of catalytic tests at variable conversion and the products identification by two-dimensional gas chromatography, a mechanistic reaction scheme has been established. Aromatic ROCPs are formed through purely acidic steps, whereas the formation of saturated ROCPs mostly involves bifunctional reaction steps. Iridium-catalyzed hydrogenolysis appears to be a minor pathway with respect to iridium-catalyzed hydrogenation and Brønsted acid catalyzed isomerization.

Incoherent light transport in an anisotropic random medium: a probe of human erythrocyte aggregation and deformation

This paper investigates the flow induced disaggregation, deformation and orientation of several modified human red blood cells suspended in concentrated, physiological like conditions (volume fraction in erythrocytes of 0.4). The aim is to determine simultaneously, and under flow, the aggregate sizes as well as the deformation and orientation of the cells. The measurement method uses steady, incoherent, unpolarized light transport while the sample is sheared in a flow cell controlled by a rheometer. Several blood samples were prepared to alter the erythrocyte's aggregating, deformability and shape properties. The measurements using these samples show a clear relationship between the intrinsic properties of the cells and the evolution of aggregate sizes, average cell orientation and anisotropy as a function of the applied shear, which may lead to clinical applications. In other words, the careful analysis of the incoherent light transport in concentrated media provides quantitative insight into their microscopic details. In particular, the topological properties (average anisotropy and orientation) and size of the suspended objects can be determined.

Opportunity of detecting pre-hypertension: worldwide data on blood pressure overswinging

Overswinging or CHAT (brief for Circadian Hyper-Amplitude-Tension), that is an excessive circadian variation in blood pressure (BP), has been associated with a large increase in cardiovascular disease risk, present even in the absence of an elevated BP itself. This usually asymptomatic condition is usually overlooked by current practice based on spot-checks, because to be diagnosed, measurements need to be taken around-the-clock, preferably for 7 days at the outset. Once diagnosed, however, a usual circadian BP pattern can be restored by means of certain non-pharmacologic or pharmacologic interventions timed appropriately. Thereby, it is possible to reduce the risk of cardiovascular morbidity and mortality, cerebral ischemic events and nephropathy in particular. For the preparation of guidelines regarding the diagnosis of BP disorders and for the institution of primary as well as secondary preventive measures, it is important to know what the incidence of CHAT is on a global basis. We found 191 cases of CHAT among 1602 mostly 7-day/24-h BP profiles, obtained from several centers in different countries participating in an ongoing project on the BIOsphere and the COSmos (BIOCOS). CHAT incidence is about the same between men and women, but it is diagnosed more often among patients with borderline hypertension or with glucose intolerance. It is also more common among MESOR-hypertensive than among MESOR-normotensive individuals. Priority should be given to the development of an unobtrusive and affordable device to automatically monitor BP and to analyze the data as-one-goes, so that cardiovascular disease risk can be prevented.

100 or 30 years after Janeway or Bartter, Healthwatch helps avoid 'flying blind'

Longitudinal records of blood pressure (BP) and heart rate (HR) around the clock for days, weeks, months, years, and even decades obtained by manual self-measurements (during waking) and/or automatically by ambulatory monitoring reveal, in addition to well-known large within-day variation, also considerable day-to-day variability in most people, whether normotensive or hypertensive. As a first step, the circadian rhythm is considered along with gender differences and changes as a function of age to derive time-specified reference values (chronodesms), while reference values accumulate to also account for the circaseptan variation. Chronodesms serve for the interpretation of single measurements and of circadian and other rhythm parameters. Refined diagnoses can thus be obtained, namely MESOR-hypertension when the chronome-adjusted mean value (MESOR) of BP is above the upper limit of acceptability, excessive pulse pressure (EPP) when the difference in MESOR between the systolic (S) and diastolic (D) BP is too large, CHAT (circadian hyper-amplitude tension) when the circadian BP amplitude is excessive, DHRV (decreased heart rate variability) when the standard deviation (SD) of HR is below the acceptable range, and/or ecphasia when the overall high values recurring each day occur at an odd time (a condition also contributing to the risk associated with 'non-dipping'). A non-parametric approach consisting of a computer comparison of the subject's profile with the time-varying limits of acceptability further serves as a guide to optimize the efficacy of any needed treatment by timing its administration (chronotherapy) and selecting a treatment schedule best suited to normalize abnormal patterns in BP and/or HR. The merit of the proposed chronobiological approach to BP screening, diagnosis and therapy (chronotheranostics) is assessed in the light of outcome studies. Elevated risk associated with abnormal patterns of BP and/or HR variability, even when most if not all measurements lie within the range of acceptable values, becomes amenable to treatment as a critical step toward prevention (prehabilitation) to reduce the need for rehabilitation (the latter often after costly surgical intervention).

Major T cell epitope-containing peptides can elicit strong antibody responses

Peptides containing major T cell epitopes have the capacity to induce T cell anergy and have therefore been proposed for the treatment of allergic and autoimmune diseases. Such peptides should not be immunogenic, i. e. should not contain a B cell recognition site. We have evaluated in BALB/c mice the therapeutic potential of a 15-mer peptide (p21 - 35) derived from Der p2, a major allergen of the house dust mite Dermatophagoides pteronyssinus, which contains a dominant T cell epitope but is not recognized by antibodies to Der p2. Unexpectedly, p21 - 35 elicited strong immune responses, suggesting the presence of a cryptic B cell epitope. Similar results were obtained with mice of three additional MHC haplotypes. A core sequence of four amino acids (Ile-Ile-His-Arg) corresponding to residues 28 - 31 was shared by the B and T cell epitopes. Critical residues for B cell recognition were Arg31 and Lys33, while Ile28 was essential for T cell recognition. A Lys33Ala mutant of p21 - 35 still activated T cells but had much reduced immunogenic properties, making it a suitable alternative peptide for T cell anergy induction. Careful investigation of the immunogenic potential of peptides used to induce T cell anergy should be carried out prior to their clinical application.

[Development and evaluation of food supplements for the education, health, and nutrition program]

OBJECTIVE

To develop and evaluate nutritional supplements destined to a program of social assistance.

MATERIAL AND METHODS

In the design of the nutritional supplements a series of criteria were considered including nutrient composition, physicochemical properties and feasibility of production and utilization. Final products were initially evaluated to determine the level of acceptance in 40 children, 52 pregnant women and 62 lactating women in Mexico City. A community trial was also carried out to determine acceptance and consumption in 108 children and 128 women from a rural community in the state of Morelos.

RESULTS

The specific formulation and technical processes of production of the nutritional supplements are presented. Products proved to be widely accepted, with average scores of 4.11-4.29 for the children's beverage, and 3.98-4.15 for a more viscous pap (range of scores was 1 to 5). Products for women received average scores from 4.75 to 5.70 in pregnant and from 4.8 to 5.4 in lactating women (range of scores from 1 to 7). In the community trial, supplements were very well accepted. Average consumption was > 75% among children and > 98% among women. Mean energy intake from supplements was 244 Kcal/day for women, and for children, 168 Kcal/day with the pap and 147 Kcal/day with the beverage. Consumption was consistent in all cases along the study.

CONCLUSIONS

Nine nutritional supplements were developed and evaluated which comply with the necessary nutritional, physicochemical and hygienic characteristics for the target population, besides being relatively simple to prepare, and widely well accepted and consumed.

[Bases for formulating a program to promote breast-feeding: methodological aspects]

Based on the relevance of breastfeeding for maternal-infant health, it is necessary that the prospective and longitudinal studies carried out in Mexico be analyzed as a whole in order to create an analytic model and to develop an institutional intervention program concerning the mother's risk of not starting or of abandoning lactation. To create this program all the factors which can be modified must be taken into account in order to make sure the mother has the elements to make a decision. The National Institute of Perinatology has developed a research program about lactation that consists of 3 studies that have been carried out since 1983. The general aim of these studies is to understand the breastfeeding phenomenon in an integral way considering the role of the institution as an educational instrument and a means of providing health support. These studies were based on different perspectives, approaches and times but had similar objectives. For this reason it is desirable to analyze them as a whole in order to obtain new considerations and temporal projections. In order to integrate the 3 studies a database will be created and then an analytical model (from a multivariate analysis) will be generated from the 1st study (by temporal order) which will be tested in the 2nd study making the pertinent modifications and finally it will be applied in the 3rd study. At the same time it will be necessary to group the variables into 2 classification systems: The first according to the temporal proximity with regard to lactation and the second according to the organization level to which they belong.

Fertility of male workers exposed to mercury vapor or to manganese dust: a questionnaire study

The fertility of male workers exposed to mercury vapor or to manganese dust was assessed with the use of the questionnaire developed by Levine et al [1980]. In the mercury group (concentration of mercury in urine ranging from 5.1 to 272.1 micrograms/g creatinine), no statistically significant difference was found between the observed number of children and that expected on the basis of the reproductive experience of a well-matched control group. On the contrary, by comparison with their corresponding controls, the manganese-exposed workers exhibited a statistically significant deficit in the number of children during their period of exposure to the metal. The airborne concentration of manganese dusts at the different workplaces ranged from 0.07 to 8.61 mg/m3 with a geometric mean of 0.94 mg/m3.

Studies on mutagenic constituents of apple brandy and various alcoholic beverages collected in western France, a high incidence area for oesophageal cancer

Apple brandies, alcoholic spirits produced in the west of France, as well as other types of alcoholic beverage (rums, whiskies, armagnacs, cognacs) were tested for mutagenicity on Salmonella typhimurium TA98 and TA100 in the plate-incorporation assay in the presence or the absence of rat-liver S9. The mutagenic activity of acrolein, gamma-butyrolactone, furfural and glycidol, chemicals usually found in these spirits, was assayed by the same procedure. Glycidol was mutagenic in TA1535 and TA100 without metabolic activation. We found higher and more frequently positive responses in home-made apple brandies than in the other beverages; therefore, further fractionation for isolation of the mutagenic compound(s) was performed by using spinning band column distillation, HPLC and gas chromatography. The fractions contained various types of mutagen, i.e., frameshift and/or base-pair substitution mutagens; some required metabolic activation and others did not in either the alcoholic, aqueous or non-volatile fractions. The results indicate that the high incidence of oesophageal cancer correlated with the alcoholic consumption in these areas might be at least partially attributable to the presence of mutagens in apple brandies.

Intake of volatile nitrosamines from consumption of alcohols

Volatile nitrosamines were determined in alcoholic drinks during epidemiologic studies on the relationship between esophageal cancer incidence and alcohol consumption in Normandy, France. Nitrosodimethylamine (NDMA) was found commonly in most alcoholic drinks tested, with the exception of wine. The average level, about 2 micrograms/liter in beers, was higher than that for other drinks; the range was 0.2--8.6 micrograms/liter. Traces of nitrosodiethylamine (NDEA) were also detected in spirits and ciders. No significant increases in levels were found after nitrosation. Calculation of daily intake in the study region showed that the main intake of volatile nitrosamine is from NDMA in beer. The intake of NDEA through consumption of cider is about one-third that of NDMA from all sources.

High resolution analysis of cervical cells--a progress report

This paper presents preliminary results of research toward the development of a high resolution analysis stage for a dual resolution image processing-based prescreening device for cervical cytology. Experiments using both manual and automatic methods for cell segmentation are described. In both cases, 1500 cervical cells were analyzed and classified as normal or abnormal (dysplastic or malignant) using a minimum Mahalanobis distance classifier with eight subclasses of normal cells, and five subclasses of abnormal cells. With manual segmentation, false positive and false negative error rates of 2.98 and 7.73% were obtained. Similar experiments using automatic cell segmentation methods yielded false positive and false negative error rates of 3.90 and 11.56%, respectively. In both cases, independent training and testing data were used.

Segmentation of cervical cell images

A major problem in the automation of cervical cytology screening is the segmentation of cell images. This paper describes various standard segmentation methods plus one which determines a segmentation threshold based on the stability of the perimeter of the cell as the threshold is varied. As well as contour, certain structural information is used to decide upon the threshold which separates cytoplasm from the background. Once the cytoplasm threshold is found, cytoplasm and nucleus are separated by simple clustering into three groups, cytoplasm, folded cytoplasm and nucleus. These techniques have been tested on 1500 cervical cells that belong to one of eight normal classes and five abnormal classes. A minimum Mahalanobis distance classifier was used to compare results. Manually thresholded cells were classified correctly 66.0% of the time for the 13 class problem and 95.2% of the time on the two (normal-abnormal) class problem. The contour tracing technique was 52.9% and 90.0% correct, respectively.