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Karin Martin

Publications and source records attributed to Karin Martin.

10 recordsLinked to original sources
PubMed2005

An easy to use method to approximate Poisson confidence limits.

Despite the ever larger choice of softwares and statistical packages allowing fast and accurate computation of binomial and Poisson confidence limits, there is always a need for a simple and reliable formula allowing non-computerized computations. The method proposed in this paper is derived from the Freeman and Tukey's variance stabilizing transformation for a random Poisson variable and adjusted for giving the best fit with the exact Poisson values. Despite its simplicity, allowing its use in any circumstances, this method provides very satisfactory results and a much better fit than classical formula based on the normal approximation, even if a continuity correction is used. It allows computation of Poisson confidence limits both for count or rates and proportions.

Biometry↗
PubMed2005

Potential impact of oral contraceptive choice on myocardial infarction mortality and deep vein thrombosis.

OBJECTIVES: To summarise the epidemiological evidence on the relationship between second- (OC2) and third-generation (OC3) oral contraceptives (OC) and the mortality associated with deep vein thrombosis (DVT) and myocardial infarction (MI), and to extrapolate and balance the evidence for these risks to the population of French OC users. METHODS: All studies published on the risk of MI during OC2 and OC3 use were analysed. For DVT the Committee for Proprietary Medicinal Products public assessment report published in 2001 and more recent studies published on this topic were used. The estimates of odds ratios (OR) for risk of death from DVT or MI were extracted from the published manuscripts. ORs were used to calculate the aetiological fraction of risk for death from DVT and MI in the population; the relative impact of OC3 compared to OC2 use was expressed as an excess risk of death overall and by age group for French women. RESULTS: Compared with OC2, the use of OC3 would prevent a maximum of 24 deaths from MI per year and induce a maximum of 16 deaths. Conversely, OC3 would induce 282-940 excess cases of DVT per year, resulting in 28-94 pulmonary embolisms and 3-19 deaths in the 4.7 million French OC users. CONCLUSION: Balancing the evidence, it is difficult to conclude that the overall cardiovascular risk is significantly lower for either of the two OC schemes.

Adult↗
PubMed2004

Segmented flow generation by chip reactors for highly parallelized cell cultivation.

Micro system technology offers convenient tools for the production of handling devices for small liquid volumes which can be used in cell cultivation. Here, a modular system for the rapid generation of cell suspension aliquots is presented. The system is used to produce and analyze high numbers of well-separated culture volumes. Selected clones may be retrieved from the system. Therefore, the principle of segmented flow is applied. Portions of aqueous culture medium containing one cell or very small cell ensembles are separated from each other by a nonmiscible liquid like dodecane, tetradecane or mineral oil. In addition, the alkane separates the culture droplets from the innerside of the walls of chip channels and capillaries. This way, compatibility problems between cell wall surfaces and the chemical character of walls are excluded. The separated culture droplets are guided by micro flow transportation in different channel and chamber topologies. The whole system has the character of a serially operating cell processing system. The aliquot generation can be sped up to frequencies of about 30 Hz in each microchannel. That means, that about 10(5) individual cultural volumes can be produced per hour or about 2 million per day. The survival and the growth of microorganisms has been shown for model organisms as well as for organisms from a natural sample (soil).

Cell Culture Techniques↗
PubMed2004

Incidence of agranulocytosis in Southwest France.

BACKGROUND: Updated knowledge of background event rates is fundamental to risk assessment. OBJECTIVE: To estimate the incidence of agranulocytosis in the general population in Southwest France. METHODS: All definite cases of acute non-cancer drug-related agranulocytosis in subjects aged more than 16 years were systematically retrieved weekly from Medical departments or labs in the catchment area (approximately 3.5 millions inhabitants). Event rates were compared to population figures from 1999 census data, and Poisson 95% confidence intervals computed. RESULTS: From January 1st 1997 to December 31st 1998, 87 cases of agranulocytosis were identified, 58 being validated by an independent ad hoc panel of experts. The overall annual incidence rate was 9.2 per million inhabitants (95%CI: 6.9;13.0); 7.7 (95%CI: 4.8;11.7) per million in men, and 10.5 (95%CI: 7.2; 14.8) per million in women. These rates of all-cause acute agranulocytosis can be used as expected background reference rate for specific risk assessment.

Acute Disease↗
PubMed2004

Differences between clinical trials and postmarketing use.

AIMS: Clinical trials constitute the gold standard to assess the efficacy and safety of new medicines. However, because they are conducted in standardized conditions far from the real world of prescription and use, discrepancies in patient selection or treatment conditions may alter both the effectiveness and risks. On the basis of three examples, our objectives were to study the differences between the characteristics of treated populations and treatment patterns in clinical trials and in postmarketing settings and to discuss the potential consequences on actual efficacy and safety. METHODS: Treated populations were compared with patients included in premarketing clinical trials. Comparisons were made on the basis of demographic characteristics and treatment patterns. RESULTS: Whatever the indicator and the drug studied, differences were observed: from 0.04% to 63% for tacrine, from 0% to 37% for celecoxib and from 6% to 52% for simvastatin, with possible consequences on the effectiveness and safety of the drug concerned. Our results confirm the under-representation of women and elderly patients in premarketing clinical trials, e.g. an M : F ratio of 4.6 in clinical trails of simvastatin vs 1.0 in the joint population. Moreover, the concomitant use of medicines was made extremely restrictive by the protocols of these trials while this was not the case in the postmarketing phase. This has possible consequences on the effectiveness and safety of the drug concerned. CONCLUSIONS: These results plead for systematic ad hoc observational postmarketing studies for any novel and/or expensive medicine to assess the relevance of premarketing data.

Adult↗
PubMed2003

Generation of larger numbers of separated microbial populations by cultivation in segmented-flow microdevices.

The high speed production of fluid segments for the highly parallelized cultivation of monoclonal cell populations was carried out by the use of microchip segmentor modules. Aqueous fluid segments, embedded in a non-miscible carrier liquid, were produced with frequencies up to 30 s(-1) and showed a high homogeneity in size. This corresponds with the production of about 2.5 million samples per day. The segment volumes can be adapted between about 4 nl and 100 nl. The typical segment size for cultivation experiments is in the range between 40 nl and 80 nl. Nutrient medium can be applied instead of pure water. It is possible to aliquot a cell suspension in such a way that most of the aqueous fluid segments contain only one cell. In model experiments with four microbial species chip-produced aliquots of 60 nl, each containing one or a few cells, were incubated in Teflon capillary tubes. Rapid growth of the microcultures was observed. Cell densities were found to be as high as in conventional shake flask cultures.

Colony Count, Microbial↗
PubMedDate not supplied

Adolescents' experiences of childbirth: contrasts with adults.

Most of what is known about the meaning women assign to the experience of childbirth in the United States is based primarily on studies of Euro American, highly educated, married women of middle to higher income levels. Yet almost half a million adolescents give birth annually. This exploratory, qualitative study was conducted with 25 adolescents in an alternative school, partnered with the juvenile justice system, who had given birth. An open-ended question format was used for the interviews, and analysis was conducted by using extended case methodology. The study revealed a number of differences between the existing literature reports about women's interpretations of birth and the meanings assigned to childbirth experiences by the adolescents in this study. A key difference was the relationship between the pain of childbirth and responsibility for their child. The results provide an entrée into understanding unique characteristics of giving birth as an adolescent and potential roles health care providers can play to promote a positive experience.

Adolescent↗
PubMedDate not supplied

NSAID use profiles derived from reimbursement data in France.

Because extrapolation of adverse event rates from clinical trials to the general population relies on the assumption of similar drug-usage patterns, we have studied usage patterns for nonsteroidal anti-inflammatory drugs (NSAIDs) from the National Health Insurance claims database. Reimbursement patterns of NSAIDs and analgesics were studied in a cohort of 232 users, half selected from authorisations of reimbursed spa cures, and the other half - strictly matched according to age and gender - who had redeemed at study onset at least one prescription for NSAIDs, analgesics or other antirheumatic drugs. Drug utilisation was measured as the total number of defined daily doses (DDD) bought over the 9-month study period. Over this time, the patients bought a median 45 DDD of NSAIDs out of the 270 needed to cover the whole period. Only two patients bought 270 DDD or more. Median paracetamol use (alone or combined) was 26 days. This study shows that patients use NSAIDs either intermittently or at lower than recommended doses, which is consistent with a primarily symptomatic use. Intermittent or on-demand use of NSAIDs, or at doses lower than full, could partly explain the lower rates of gastrointestinal bleeding and other ulcer complications in postmarketing epidemiological studies than could be expected from the findings of clinical trials.

Adult↗