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PubMedDate not supplied

An alternative procedure for fitting relational model life tables.

"The paper considers the problem of fitting a relational model life table to mortality data which does not include reliable estimates of infant and child mortality. This type of data could arise from indirect estimation of adult mortality using orphanhood or widowhood, or from adjustment of incomplete registration data using growth balance methods in a population recently de-stabilized by falls in fertility. The proposed fitting technique can give equal weight to all the age specific mortality risk information available, rather than giving more weight to the information for younger ages, as is the case with the traditional method. An application to Brazilian data is presented." (SUMMARY IN ITA AND FRE)

Americas↗

PubMed1986

Differential mortality in Turkana agriculturalists and pastoralists.

Nomadic pastoral populations appear to have much lower rates of growth than the otherwise very high growth rates now characteristic of populations in developing nations. Because dramatic declines in infant mortality have been a primary contributor to increased population growth rates in these countries, it has been assumed that nomadic pastoral populations are still characterized by high levels of mortality in the first few years of life. Few studies, however, have been undertaken to estimate demographic parameters for nomadic pastoral populations, and even fewer of a comparative nature have been undertaken to document the impact of subsistence strategy on demographic processes. This study compares indirect childhood mortality estimates for Turkana nomadic pastoralists with childhood mortality in a settled agricultural group within the same population and finds that pastoralists have substantially higher levels of mortality. Based on the childhood mortality estimates, model life tables are selected for pastoral and agricultural groups from which values for mean life expectancy and infant mortality are estimated and compared. Recent improvements in primary health care for the settled agricultural group are ruled out as being an important cause of their lower mortality levels, and some aspects of life-style associated with subsistence strategy are discussed as likely determinants of the mortality differences.

Adolescent↗

PubMed1985

[Some problems concerning the selection of the most appropriate mortality model for the indirect estimation of infant mortality].

"This paper analyzes the problems that arise when infant mortality estimates are derived through the probabilities of dying obtained from the application of the Coale-Trussell technique to the proportion of children deceased according to age of mother derived from census or survey data. These problems arise because this operation requires the acceptance of a mortality model by age." The author outlines "some criteria for the selection of the model through the use of information from Vital Statistics and surveys. Finally, it is stated that an alternative for the study of infant mortality trends is the selection of an indicator less affected by the mortality structure by age...." The problems are illustrated using data from selected countries in Latin America. (summary in ENG)

Age Factors↗

PubMed2005

Characterizing dye bias in microarray experiments.

MOTIVATION: Spot intensity serves as a proxy for gene expression in dual-label microarray experiments. Dye bias is defined as an intensity difference between samples labeled with different dyes attributable to the dyes instead of the gene expression in the samples. Dye bias that is not removed by array normalization can introduce bias into comparisons between samples of interest. But if the bias is consistent across samples for the same gene, it can be corrected by proper experimental design and analysis. If the dye bias is not consistent across samples for the same gene, but is different for different samples, then removing the bias becomes more problematic, perhaps indicating a technical limitation to the ability of fluorescent signals to accurately represent gene expression. Thus, it is important to characterize dye bias to determine: (1) whether it will be removed for all genes by array normalization, (2) whether it will not be removed by normalization but can be removed by proper experimental design and analysis and (3) whether dye bias correction is more problematic than either of these and is not easily removable. RESULTS: We analyzed two large (each >27 arrays) tissue culture experiments with extensive dye swap arrays to better characterize dye bias. Indirect, amino-allyl labeling was used in both experiments. We found that post-normalization dye bias that is consistent across samples does appear to exist for many genes, and that controlling and correcting for this type of dye bias in design and analysis is advisable. The extent of this type of dye bias remained unchanged under a wide range of normalization methods (median-centering, various loess normalizations) and statistical analysis techniques (parametric, rank based, permutation based, etc.). We also found dye bias related to the individual samples for a much smaller subset of genes. But these sample-specific dye biases appeared to have minimal impact on estimated gene-expression differences between the cell lines.

Algorithms↗

PubMed2002

Irritable bowel syndrome in Germany. A cost of illness study.

OBJECTIVES: When asked, between 10% and 15% of people in the Western world report symptoms compatible with irritable bowel syndrome, and around 5% seek medical advice for these complaints. This should incur considerable costs. The present study was designed to give a cost estimate for the treatment of patients with irritable bowel syndrome paid for by German statutory health insurance. METHODS: Fifty doctors working in private practice were randomly selected to each carry out personal interviews on four irritable bowel syndrome patients chosen from their own records (total 200 patients). Using a structured questionnaire, information regarding diagnostic procedures, drugs and other therapies, hospitalization and days off work were obtained from the case records. To calculate the total direct costs of the illness, all single cost elements such as physician services, medication and hospitalization were included. RESULTS: The number of office visits was nine per patient per year; nearly one-third of employed patients missed work for irritable bowel syndrome, and one out of 15 patients was hospitalized for this condition. Several technical procedures were ordered, mostly laboratory tests. Nearly all patients had at least one drug prescription for irritable bowel syndrome during the year of the survey, with a mean of 3.5 prescriptions per patient. The largest pharmacological groups were antispasmodics (29.2%) and prokinetics (8.9%). Total direct costs for one irritable bowel syndrome patient per year amounted to 1548 DEM (791.48 [OV0556]), comprising roughly 25% for physician visits and tests, 50% for drugs and 25% for hospitalization. Including indirect costs for sick leave, total costs were 1946 DEM (994.97 [OV0556]) per patient per year. CONCLUSIONS: The costs incurred by irritable bowel syndrome are considerable.

Colonic Diseases, Functional↗

PubMed1992

[Hemostasis screening in the emergency laboratory].

PURPOSE: While automation of laboratories is of great value for analysts, as it makes technical work easier, and for clinicians, as the results are available in a shorter time, the requests increase strikingly bringing about higher costs. The emergency laboratory is an example of what happens in the general laboratory. In order to make an estimate of this subject, the haemostasis screening was chosen since it is a recently automated technique in that laboratory, attention being paid to the aim and indication of the screening and its economical burden. MATERIAL AND METHODS: A study of the haemostasis screening performed during July 1990 was carried out of considering the 24 hours per day work. The requests were classified, in accordance with their indication, as diagnostic, pre-surgical, therapeutic or unknown; the justification and purpose of those requests was also examined. RESULTS: The total number of studies performed in that month was 1,273, with a daily mean of 41, as opposed to 2,095 performed in the haemostasis laboratory in the same period. According to the American Medical Association criteria only 48% of the requests could be warranted, and abnormal findings appeared in only 10% of them. CONCLUSIONS: The cost per isolated parameter is low, but it increases greatly when compared with the benefit that it reports to the patient because, as those biological tests indirectly measure the concentration of clotting factors, they are subjected to error when performed by non-specialized personnel; on the other hand, the most valuable information for detecting haemorrhagic troubles comes from the patient's history. The economical burden in the month studied amounted to 985,879 PTA; one year later, the same laboratory, in the same month, had a 50% increase of studies.

Blood Coagulation Disorders↗

PubMedDate not supplied

Chromosome studies in human sperm nuclei using fluorescence in-situ hybridization (FISH).

The use of chromosome specific DNA probes labelled with fluorochromes and especially the combination of several probes has been used to indirectly study the chromosome constitution of decondensed sperm nuclei by fluorescence in-situ hybridization (FISH), and has allowed to include this test in the protocol of study of infertile males. Still, if the test is to be valid, several strict conditions must be met, and some specific characteristics have to be taken into account. This becomes evident when comparing earlier results with more recent ones. The basic technical factors to be taken into account are the methods of chromatin decondensation, the number of spermatozoa and of individuals to study, the use of internal controls, the scoring criteria, the specificity of the probes and the possible existence of polymorphisms that may interfere with the detection of fluorescent signals. In the last 7 or 8 years, a large number of papers has been published, describing the incidence of aneuploidies in controls, in individuals in whom a tendency to non-disjunction was suspected and in infertile males. Studies in controls have shown a considerable intra- and inter-individual variability in the frequency of aneuploidies, the tendency of some chromosomes to undergo non-disjunction (chromosome 21 and the sex chromosomes) and the importance of alpha-satellite polymorphisms when using centromere probes. In the control population, the frequency of aneuploidy per haploid set has been estimated at approximately 6%. The incidence of aneuploidies in sperm nuclei for some of the chromosomes more frequently involved in trisomies is considerably higher than the incidence of these trisomies established through epidemiological data using the global incidence of chromosome abnormalities during the peri-implantation stage. In infertile males and in males with sex-chromosome abnormalities (usually with very low numbers of spermatozoa) the results show an increased incidence of sex chromosome aneuploidies and diploid (multi-aneuploid?) sperm nuclei. The results could be related to the higher incidence of chromosome abnormalities (especially sex-chromosome aneuploidies) observed in children conceived by intracytoplasmic sperm injection (ICSI).

Cell Nucleus↗

PubMed1987

[Quantification of radiation-induced genetic risk].

Associated with technical advances of our civilization is a radiation- and chemically-induced increase in the germ cell mutation rate in man. This would result in an increase in the frequency of genetic diseases and would be detrimental to future generations. It is the duty of our generation to keep this risk as low as possible. The estimation of the radiation-induced genetic risk of human populations is based on the extrapolation of results from animal experiments. Radiation-induced mutations are stochastic events. The probability of the event depends on the dose; the degree of the damage does not. The different methods to estimate the radiation-induced genetic risk will be discussed. The accuracy of the predicted results will be evaluated by a comparison with the observed incidence of dominant mutations in offspring born to radiation exposed survivors of the Hiroshima and Nagasaki atomic bombings. These methods will be used to predict the genetic damage from the fallout of the reactor accident at Chernobyl. For the exposure dose we used the upper limits of the mean effective life time equivalent dose from the fallout values in the Munich region. According to the direct method for the risk estimation we will expect for each 100 to 500 spontaneous dominant mutations one radiation-induced mutation in the first generation. With the indirect method we estimate a ratio of 100 dominant spontaneous mutations to one radiation-induced dominant mutation. The possibilities and the limitations of the different methods to estimate the genetic risk will be discussed. The discrepancy between the high safety standards for radiation protection and the low level of knowledge for the toxicological evaluation of chemical mutagens will be emphasized.

Accidents↗

PubMed1979

A method of estimating adult mortality trends from widowhood and death distribution data.

"This paper is an attempt to find a procedure for estimating past trends in the rate of decline of adult mortality [using] data collected during a census or a single sample survey. It indirectly focuses on trends in adult death rates by looking at proportions not-widowed by age-groups and changes in these proportions caused by diminishing death rates. An equation has been developed which expresses the proportion not-widowed of the ever-married population in an age-group as a function of the current level of mortality in the population, a first marriage frequency distribution, and the past rate of mortality decline." The technique is applied to data from the 1974 Bangladesh Retrospective Survey of Fertility and Mortality.

Adult↗

PubMed2004

[Antimicrobial prophylaxis in surgical procedures: assessment of the guidelines application and validation of antibiotic prophylaxis kits].

INTRODUCTION: Surgical wounds infections represent a major cause of morbidity and are at the origin of an increase in the postoperative mortality rate. Those infections represent in France one-fourth of the nosocomial infections. Combine with the elementary hygiene rules and the surgical "good practices", antimicrobial prophylaxis with antibiotics is an essential tool for the reduction of the surgical wound infections rate. In the French hospitals, antimicrobial prophylaxis represents one-third of the antibiotic prescriptions. The rules for the application of surgical prophylaxis are based on current guidelines for antibiotic prophylaxis, however, guidelines are not totally respected. MATERIALS AND METHODS: Study 1: assessment of the guidelines application (practical audit) of the antibiotic antimicrobial prophylaxis in surgery, and of their impact on the established prescriptions: three audits were realized with four years interval (1994, 1998 and 2002), in order to estimate the evolution in the application of the current guidelines, which indirectly estimate the evolution of the guidelines impact. Study 2: assessment of the use of an antibiotic kit through a prospective comparative study of two groups: exposed patients vs non-exposed patients. Nominatives kits contained the recommended antibiotics with recommended posology and the instructions for each surgical procedure. RESULTS: Study 1: this study showed a significant increase in the antibiotics prescription volume since 1994 (+23%). After a temporary increase from 1994 to 1998, the conformity of the effective prescriptions with the current guidelines for the indication to realize or not to realize an antibiotic surgical prophylaxis decreases of 7% between 1998 and 2002. Nevertheless, we noticed an overall improvement in the guidelines application for the modalities of the antimicrobial prophylaxis when it was prescribed in a valid indication. Persistent weak points were in 2002 the antibiotic molecule choice (error rate of 25%), the duration of prescription (rate of abnormal prolonged antibiotic prophylaxis of 19%), and the timing of administration (error rate of 31%). Study 2: antibiotic kits have permitted to increase the accordance of the antimicrobial prophylaxis prescriptions with the guidelines. Antibiotic prophylaxis was in total agreement with guidelines for 82% of exposed patients vs 41 for non-exposed patients. Choice of the antibiotic molecule, timing of administration and duration of prescription were the parameters particularly well rectified by this new antibiotic prophylaxis technical. CONCLUSION: In this study, guidelines diffusion seems to be an essential but also an insufficient point for the improvement of the quality prescriptions in surgical antimicrobial prophylaxis. The "day by day" nominative antibiotic prophylaxis deliverance in the shape of a << ready to use >> antibiotic kit went with an increase in the respect of the recommendations, by correcting in a significant way the persistent weak points identified during the first part of our study. The antibiotic prescriptions control is an imperative goal in individual health (the patient himself), but also in public health (the community). This radical change in habits is listed in a policy of antimicrobial agent prescription improvement (best efficacy with less cost).

Antibiotic Prophylaxis↗

PubMed2002

Cost estimation of thyroid disorders in Germany.

To assess the economic effects of thyroid disorder-related morbidity in Germany, a systematic review of national and international literature from 1981-2001 was performed. Data from insurance companies, the government department of public health, and the federal office of statistics helped characterize the situation in Germany. Being the most important thyroid disease, endemic iodine-deficiency goiter causes economic costs of approximately 2.1 billion DM per year or 1 billion Euros or 1 billion U.S. dollars. In recent years iodine supplementation of food became better accepted by the German population. This should significantly reduce the prevalence of goiter from 30%-40% to less than 10%. Functional thyroid disorders are observed in 5%-10% of the German population. A more differentiated view of these conditions should lead to specific guidelines for an economic screening and therapy of subpopulations. Lacking valuable data, an actual economic assessment of autoimmune or malignant thyroid diseases cannot be performed. On the other hand, with respect to the costs of specific thyroid therapy, e.g., radioiodine treatment of thyrotoxicosis (mainly toxic nodular goiter), the economic consequences of a new regulation for radiation protection in Germany have been demonstrated recently. Using the actual maximum permissible level of residual activity on discharge from the hospital after radioiodine therapy, length of hospitalization was shortened to 5.1 days in university hospitals and to 5.8 days in nonuniversity institutions. Payment per patient for radioiodine therapy was 1,856 and 1,530 Euros (median value) in university and nonuniversity hospitals, respectively. In conclusion, better prevention of iodine deficiency and its long-term consequences should effectively reduce direct as well as indirect costs and overall economic impact of endemic goiter as the most important thyroid disease in Germany. Sustainable elimination of iodine deficiency is technically possible, but it needs further commitment and support at all levels.

Costs and Cost Analysis↗

PubMed1993

Maternal mortality in rural communities of Illubabor, southwestern Ethiopia: as estimated by the "sisterhood method".

In this study, the "sisterhood method", a new indirect technique, utilizing a cross-sectional survey by retrospective recall for deriving population-based estimates of maternal mortality for rural communities, was used in rural Illubabor region, Southwestern Ethiopia, in December 1991. The findings indicate a lifetime risk of maternal mortality of 0.0426, or 1 in 23 women; approximating a maternal mortality ratio of 570 per 100,000 live-births. The communities experience high maternal mortality which is compounded by high fertility as reflected by the total fertility rate of 7.6. The method can readily be applied to our settings to estimate the lifetime risk of maternal mortality and derive the maternal mortality ratio. In order to generate awareness, support planning and intervention strategies, community-based estimates of maternal mortality will remain a priority where vital events registration is non-existent and health service statistics are not reliable.

Adolescent↗

PubMed1995

[Quality control of the micro-ELISA technic applied to the diagnosis of human and canine visceral leishmaniasis].

Visceral leishmaniasis (VL) or kala-azar is, in Portugal, a zoonosis with the dog as reservoir. A quality control of the technique of micro-ELISA was carried out, using as reference the technique of IFI, the most commonly used for the diagnosis of this protozoosis, both for human and canine sera. Three different methods were used to estimate the cut-off point: X + 2sd (average for negative sera plus two standard deviation), P/N and J index. As quality parameteres were used sensitivity, specificity, efficacy and positive predictive value. The cut-off point for human sera was established at 0.100 A, with 100% sensitivity, 90.5% specificity, 95.3% efficacy and 91.4% positive predictive value, and for canine sera in 0.200 A, with 80.0% sensitivity, 94.3% specificity, 87.7% efficacy and 96.6% positive predictive value. Reproducibility was not fully satisfactory and two different ways of improving it are proposed: P/N and a correction factor. A statistically significant correlation was observed between micro-ELISA's absorbances and IFI titres regarding human sera, though it was not possible to do the same for dog sera.

Animals↗

PubMed1998

[Viremia levels of the chronic hepatitis c virus in HIV infected patients, clinical implications].

BACKGROUND: To know the clinical implications of the viremia level and its evolution in time of the hepatitis C virus (HCV) in patients with chronic hepatitis and infected with the Human Immunodeficiency Virus (HIV). PATIENTS AND METHODS: We have studied the viremia level of the HCV in a a 38 patients group with active chronic hepatitis and infected with the HIV, using a quantitative PCR technic (Amplicor HCV, Roche Diagnostics); we had histological data in 33 of these patients. In 20 patients was analyzed the evolution in time of the viremia level with two or three serialized measurements (20 and 10 patients respectively), throughout 7.5 and 14.8 months on the average. We have analyzed some aspects like the risky behaviors associated with transmission, the estimated time from the contagious, the degree of histological damage and the immunitary impairment. RESULTS: We have observed a tendency to present a higher viremia level (logarithmic expression) with longer evolution time from the infection (p = 0.08). The viral load had an inverse relation with the degree of histological fibrosis (Light fibrosis: 4.5 +/- 0.8 log vs Severe fibrosis: 3.7 +/- 0.8 log) (p < 0.01) and a direct relation with the Knodell histological activity index (HAI), only with those patients with a lower fibrosis degree (p < 0.01). There was no relation between the viremia level of the HCV and the degree of immunosuppression measured by the CD4 lymphocyte count, at least in those patients in which it was higher than 200/mm3. We have not observed relations between the viral load and the age or the transaminases level. The evolution in time of the viremia tended to rise from 3.7 +/- 1.3 to 4.5 +/- 0.9 log in 14.8 months on the average, although there were some cases with tendency to decrease. We have not observed relation between its increase/month and the degree of histological damage or the CD4 lymphocyte count. CONCLUSIONS: The viral load of the HCV in HIV-infected patients seems to have an inverse relation with the degree of liver fibrosis and direct relation with the histological activity when the fibrosis light and so it could indirectly inform us about the liver aggression. The degree of immunosuppression measured by the CD4 lymphocyte count, when these are > 200/mm3, doesn't seem to influence the viremia level of the HCV. The evolution of the viral load in time tend to rise although there could be some cases with intermittent or descending evolution, without these tendencies have any clinical implications.

HIV Infections↗

PubMed2005

[The tobacco problem in French-speaking Africa and regional perspectives of the French-speaking African tobacco observatory].

The tobacco problem is one which is both global and political. The epidemic and the growing smoking crisis in Africa is a menace to the health of our continent, with significant socio-economic repercussions to follow in the coming years. Approximately 1.1 billion people around the world smoke, and between now and the year 2025, this number will most likely increase to 1.6 billion. By 2030, 10 million tobacco-related deaths will have occurred, and for the most part those deaths will be concentrated in developing countries. The tobacco industry clearly lies at the heart of the development of the tobacco pandemic in the 20th century. Specifically, cigarettes have made tobacco a massively consumed product, constantly expanding and opening up new markets; the day before yesterday it was men, yesterday it was women and youth, and today it is the developing world. The strategy is identical: increase sales, and do goat a price which puts a heavy burden on the population's health. The industries turn themselves towards developing countries, and namely Africa, in order to compensate for their losses in the markets of the Northern Hemisphere at a time when the demand in these countries is decreasing. The industry's cynical strategy targets Africa as its strongest potential market for development, counting on an estimated increase in consumption of 16% over the next decade, according to WHO's recent World Tobacco Atlas. The illegal importation of cigarettes is a practice which is growing more and more within African countries, with a well-structured African network for smuggling. Smuggled cigarettes are even more toxic with very elevated levels of nicotine and tar. Sponsorship as well as direct and indirect advertising are rapidly developing in all kinds of formats, with a proliferation of aggressive advertising messages targeting African populations with cynicism, manipulation, the complicity of smuggling in broad daylight, and disrespect for the law, while exploiting all of the themes which promote tobacco use to the target audiences (youth, women, the poorest groups). Everyday the tobacco industry recruits new African smokers to replace those who die. The future of the industry is represented by about 8 out of 10 people who began smoking before the age of 18 years old. It was imperative to establish a Tobacco Observatory in Francophone Africa (OTAF) in order to resituate the African tobacco situation, contribute to the development of the French-speaking nations in Africa, and to make known and increase awareness of its needs, its initiatives, and its actions across the world, and finally to effectively fight against tobacco and the industry's practices. One year after OTAF was established in Bamako thanks to the consolidated efforts of all its members and support of the French League against Cancer and the International Union against Cancer, OTAF OTAF is an independent entity whose mission is to gather, analyse and disseminate information on all aspects of tobacco with the objective of soliciting and supporting public health activities and interventions. It is a reference centre for Francophone Africa and a technical advisory group for the public authorities on tobacco issues. OTAF's work is counted upon to inform the public authorities on the most effective measures to use in the fight against tobacco. OTAF's duty is to promote activities which protect the health of young people and non-smokers, and communicate on the harmful effects of tobacco and the tobacco industry's practices. The goal is to organise a fight against tobacco based on solid, scientific data of the highest level of quality. OTAF is the only Francophone African surveillance organisation for monitoring the tobacco epidemic, and the practices, schemes and methods of the tobacco industry which are known to be dishonest Today, OTAF is a unique reference centre as far as the fight against tobacco is concerned in Francophone Africa. It is a partner in a number of projects with the French League against Cancer, the International Union against Cancer, and the International Union for Health Promotion and Education, among others. The success of OTAF has been crowned by a trophee having been awarded by WHO and an honorary degree signed by WHO's Director General.

Africa, Northern↗

PubMed1989

Societies in transition: mortality patterns in Pacific Island populations.

The 22 Pacific Island countries and territories are in a state of demographic and epidemiological transition. Mortality data for the period around 1980 were collected from various sources and are presented in this comparative study. Because death registration in many Pacific countries is deficient some data have been adjusted for underenumeration; and some mortality estimates have been calculated by indirect means, using data from censuses or surveys. Cause of death information is affected by diagnostic inaccuracy and often tabulated in broad categories only; in some Pacific countries cause of death data are only available on hospital deaths. The less developed Melanesian malarious countries and the less developed dispersed atoll nations manifest higher mortality, and higher proportional mortality from infectious disease compared with other states. The more developed US-associated states, two New Zealand-associated states, and New Caledonian Europeans all have reasonably low mortality, and relatively high proportional mortality from cardiovascular disease (CVD). Females have longer life expectancy at birth than males in all countries except Vanuatu and the Solomon Islands. The phosphate-rich island of Nauru presents an atypical picture with considerable adult male mortality from diseases associated with modernization.

Adolescent↗

PubMed2004

Diagnostic accuracy of ten second-generation (human) tissue transglutaminase antibody assays in celiac disease.

BACKGROUND: Anti-tissue transglutaminase (tTG) assays that use human tTG as antigen have recently become available. We evaluated commercially available assays with human tTG antigen to estimate their diagnostic accuracies and to determine whether they agree sufficiently to be used interchangeably. METHODS: Ten commercially available second-generation anti-tTG assays were evaluated. The following populations were studied: celiac disease (CD) patients at the time of diagnosis without (n = 70) or with (n = 5) IgA deficiency; diseased controls (n = 70); and CD patients without (n = 28) or with (n = 2) IgA deficiency during follow-up. All individuals included in the study underwent intestinal biopsy. Technical performance (linearity, interference, precision, correlation, and agreement) and diagnostic accuracy (sensitivity and specificity) were compared. Anti-gliadin and anti-endomysium antibodies were also measured. RESULTS: IgA anti-tTG results correlated well overall, but numerical values differed. Diagnostic sensitivity ranged between 91% and 97% and specificity between 96% and 100%. These were higher than the sensitivity and specificity of the IgA endomysium assay and the IgA gliadin assay. Generally, IgG anti-tTG was less sensitive but more specific than IgG anti-gliadin for the diagnosis of CD in the small group of IgA-deficient patients. CONCLUSIONS: Overall diagnostic performance of IgA tTG assays is acceptable and comparable among the different assays, but numerical values differ. Standardization is needed.

Adolescent↗

PubMed1999

A new measuring device for non-invasive determination of oxygen partial pressure and oxygen conductance of the skin and other tissues.

About fifty percent of the oxygen consumption of the skin is supplied by diffusion through the surface. This portion of the skin oxygen supply becomes of high importance in case of arterial occlusion. The oxygen permeation coefficient (P) of the upper layers and the oxygen pressure field within the skin determine the diffusive oxygen uptake from the outside. To our knowledge, the permeation coefficient (P) until now was only estimated by indirect methods of little practicability (Baumberger et al., 1951; Eberhard et al., 1978). An oxygen partial pressure of the skin is conventionally measured by modified CLARK type electrodes. A disadvantage of this so-called transcutaneous electrode is its oxygen consumption and the fixed coupling of the consumption with the oxygen pressure to be determined. Therefore the measurement always induces a systematic error (the so-called stirring effect) which depends, among other factors, on the oxygen availability of the skin under the electrode. The new device combines a consumption-free oxygen partial pressure detector on the basis of luminescence quenching by oxygen with an independently working specific oxygen consumer realized by an active galvanic chain (silver-lead element). The chain permits setting any oxygen mass flow (mO2) in a certain range by varying the electrode current choosing different resistors within the electrical circuit. According to the diffusion law, the surface oxygen pressure (ePO2) being measured is a linear function of the oxygen flow (mO2) directed to the cathode: ePO2 identical to -(1/P).(mO2/A) + icPO2; A: area under the cathode. The intracutaneous oxygen partial pressure (icPO2) is a virtual quantity defined by the equation given. Only by using an active electrode different oxygen mass flows can be set and so the oxygen conductance of the upper skin layers can be assessed. First experiments on human skin in the gluteal region of an adult delivered an estimated value of the permeation coefficient (P): 2.2.10(-5) ml O2 (STPD)/(atm.s.cm2) at 42 degrees C skin surface temperature; the intracutaneous partial pressure obtained was 5.5 kPa (41 mmHg) (STPD: "standard temperature pressure dry" conditions of the gas). At 42 degrees C skin temperature no burning occurs. The determined O2-conductance is in the same range as estimated formerly (see above). The intracutaneous oxygen partial pressure determined seems to be a realistic value of the tissue at 42 degrees C. By in vitro measurements with technical membranes the new device and procedure was validated giving precise values of the oxygen conductance. Hence the new method may be used for calibration of the oxygen flux optode (Holst et al., 1993). The O2-permeation coefficient (P) could be an important parameter for evaluating dermatological applications (which attempt to increase P) in the treatment of local dermal oxygen deficiency. The intracutaneous oxygen partial pressure found is a reasonable value for a surface temperature of 42 degrees. Because of the independence of the O2-partial pressure determined and the O2-consumption the new device exhibits no stirring effect and it provides more insight into the limitations of conventional transcutaneous oxygen measurement.

Adult↗