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Biomedical subjects

C Martin

Publications and source records attributed to C Martin.

At least 289 records · Page 16Linked to original sources
PubMed1999

A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group.

BACKGROUND: To determine whether a restrictive strategy of red-cell transfusion and a liberal strategy produced equivalent results in critically ill patients, we compared the rates of death from all causes at 30 days and the severity of organ dysfunction. METHODS: We enrolled 838 critically ill patients with euvolemia after initial treatment who had hemoglobin concentrations of less than 9.0 g per deciliter within 72 hours after admission to the intensive care unit and randomly assigned 418 patients to a restrictive strategy of transfusion, in which red cells were transfused if the hemoglobin concentration dropped below 7.0 g per deciliter and hemoglobin concentrations were maintained at 7.0 to 9.0 g per deciliter, and 420 patients to a liberal strategy, in which transfusions were given when the hemoglobin concentration fell below 10.0 g per deciliter and hemoglobin concentrations were maintained at 10.0 to 12.0 g per deciliter. RESULTS: Overall, 30-day mortality was similar in the two groups (18.7 percent vs. 23.3 percent, P= 0.11). However, the rates were significantly lower with the restrictive transfusion strategy among patients who were less acutely ill -- those with an Acute Physiology and Chronic Health Evaluation II score of < or =20 (8.7 percent in the restrictive-strategy group and 16.1 percent in the liberal-strategy group; P=0.03) -- and among patients who were less than 55 years of age (5.7 percent and 13.0 percent, respectively; P=0.02), but not among patients with clinically significant cardiac disease (20.5 percent and 22.9 percent, respectively; P=0.69). The mortality rate during hospitalization was significantly lower in the restrictive-strategy group (22.3 percent vs. 28.1 percent, P=0.05). CONCLUSIONS: A restrictive strategy of red-cell transfusion is at least as effective as and possibly superior to a liberal transfusion strategy in critically ill patients, with the possible exception of patients with acute myocardial infarction and unstable angina.

APACHE↗
PubMed1999

Clinical follow-up of high mid-trimester maternal serum intact human chorionic gonadotrophin concentrations in singleton pregnancies.

Mid-trimester biochemical screening of 38 143 pregnancies in south-east Scotland revealed 127 cases (0.34 per cent) in which the maternal serum (MS) intact human chorionic gonadotrophin (hCG) concentration was > or = 4 multiples of the median in singleton pregnancies (MOM). Three were lost to follow-up but in 72 (58 per cent) complications developed or there were associated fetal abnormalities. This percentage was greatest at very high hCG concentrations, 92 per cent with hCG > or = 10 MOM (n = 12) compared with 48 per cent with hCG concentrations of 4-4.99 MOM (n=69). 22 cases had an MS alpha-fetoprotein > or = 2 MOM in addition to an MS hCG > or = 4 MOM, and in only 3 of these was the pregnancy uneventful; 86 per cent were associated with abnormalities or pregnancy complications.

Chorionic Gonadotropin↗
PubMed1999

T2 vertebral bone marrow changes after space flight.

Bone biopsies indicate that during immobilization bone marrow adipose tissue increases while the functional cellular fraction decreases. One objective of our Spacelab flight experiment was to determine, using in vivo volume-localized magnetic resonance spectroscopy (VLMRS), whether bone marrow composition was altered by space flight. Four crew members of a 17 day Spacelab mission participated in the experiment. The apparent cellular fraction and transverse relaxation time (T2) were determined twice before launch and at several times after flight. Immediately after flight, no significant change in the cellular fraction was found. However, the T2 of the cellular, but not the fat component increased following flight, although to a variable extent, in all crew members with a time course for return to baseline lasting several months. The T2 of seven control subjects showed no significant change. Although these observations may have several explanations, it is speculated that the observed T2 changes might reflect increased marrow osteoblastic activity during recovery from space flight.

Adult↗
PubMed1999

Changing a hydrophobic heat and moisture exchanger after 48 hours rather than 24 hours: a clinical and microbiological evaluation.

OBJECTIVE: Complications following ventilation with dry and cold gases may be prevented by the use of artificial noses or heat and moisture exchangers, which are a solution to both the problems of humidification and heat preservation. The aim of the present study was to determine whether changing hydrophobic heat and moisture exchangers (HMEs) every 48 h rather than 24 h would affect their efficacy to preserve the heat and moisture of inspiratory gases. The impact of a prolonged use of the HME on its microbial colonization was also assessed. DESIGN: Prospective observational study. SETTING: ICU of a university hospital. PATIENTS: Twelve patients requiring controlled mechanical ventilation for more than 2 days were evaluated. INTERVENTIONS: The patients were ventilated with a heat and moisture exchanger (HME) (Maxipleat Filter, Europe Medical, France). The hydrophobic HME was placed between the Y-piece and the connecting tube and changed after 48 h of continuous use. Temperature (degree C), relative humidity (%) and absolute humidity (mgH2O/l) were obtained using the capacitive sensor principle. Bacterial colonization (tracheal secretions and ventilator side of the HME) were obtained on days 1 and 2. MEASUREMENTS AND RESULTS: After 48 h of ventilation with the same HME, tracheal tube occlusion was never observed. Using the same hydrophobic HME for 48 h rather than 24 h did not affect its technical performance: temperature at 24 h: 32.5 +/- 1.3 degrees C, at 48 h: 32.7 +/- 1.8 degrees C; relative humidity (RH) at 24 h: 99.0 +/- 1.4%, at 48 h: 99.0 +/- 1.4%; absolute humidity (AH) at 24 h: 34.0 +/- 2.4 mgH2O/l, at 48 h: 34.4 +/- 3.5 mgH2O/l. Peak and mean airway pressures did not change over the 48-h study period, with identical tidal and minute volumes in the study patients. Total respiratory heat losses were not modified during the 48-h study period (at 24 h: 152 +/- 47 cal/min, at 48 h: 149 +/- 65 cal/min). Evaporative and convective heat losses were not modified either. On day 1, eight patients had positive cultures of their tracheal secretions at a colony count of 10(3) or higher cfu/ml. After 48 h of use of the same HME, only six patients had a positive culture of their tracheal secretions. Cultures from the ventilator sides of the HMEs were all sterile (12/12) after 48 h of use. CONCLUSIONS: Changing the hydrophobic HME after 48 h rather than 24 h did not affect its technical performance in terms of heat and water preservation of ventilatory gases. There is also some indirect evidence of very little, if any, change in HME resistance. No bacterial colonization of the ventilator sides of the HMEs was observed after 48 h of use. However, other large clinical trials should be undertaken to confirm the safety of extending the time between HME changes.

Adult↗
PubMed1999

What guides the selection of alternate foot placement during locomotion in humans.

Our goal was to understand the bases for selection of alternate foot placement during locomotion when the normal landing area is undesirable. In this study, a light spot of different shapes and sizes simulated an undesirable landing area. Participants were required to avoid stepping on this spot under different time constraints. Alternate chosen foot placements were categorised into one of eight choices. Results showed that selection of alternate foot placement is systematic. There is a single dominant choice for each combination of light spot and normal landing spot. The dominant choice minimises the displacement of the foot from its normal landing spot (less than half a foot length). If several response choices satisfy this criterion, three selection strategies are used to guide foot placement: placing the foot in the plane of progression, choosing to take a longer step over a shorter step and selecting a medial rather than lateral foot placement. All these alternate foot-placement choices require minimal changes to the ongoing locomotor muscle activity, pose minimal threat to dynamic stability, allow for quick initiation of change in ongoing movement and ensure that the locomotor task runs without interruption. Thus, alternate foot-placement choices are dependent not only on visual input about the location, size and shape of the undesirable surface, but also on the relationship between the characteristics of the undesirable surface and the normal landing area.

Adult↗
PubMed1999

Malignant degeneration of an osteochondroma with unusual intra-bursal invasion.

Multiple hereditary osteochondromatosis is an uncommon autosomal dominant condition in which patients are predisposed to the development of chondrosarcoma. We report a case of a patient who developed a secondary low-grade chondrosarcoma in this setting. The tumor was associated with an unusual multinodular invasive growth pattern into a pre-existing bursa that was present overlying the osteochondroma.

Adult↗
PubMed1999

[Adenocarcinoma of unknown primary site with thoracic localization and HIV: four case reports].

INTRODUCTION: Non AIDS-defining cancer would have increased in HIV-patients as suggested by numerous studies. Four cases of adenocarcinoma of unknown primary site with thoracic localization that occurred in HIV-infected patients are described. EXEGESIS: To date, there have been no published data about carcinomas of unknown primary site relating to HIV-infected patients; however, immunodepression could promote them. Carcinomas of unknown primary site account for 0.5 to 10% of all cancer in general population. Primary carcinoma is identified in approximately one third of the cases and often corresponds to lung cancer in case of sus-diaphragmatic metastasis, particularly in case of pleural metastasis. Lung cancer in HIV-infected patients affects mostly young men who smoke and are often intravenous drug addicts. Adenocarcinoma is the most common histological type of cancer. CONCLUSION: Further studies of lung cancer in HIV-infected patients will help evaluate their frequency. In case of increasing frequency, lung cancer should then be included in AIDS-defining cancers.

Adenocarcinoma↗
PubMed1999

Spaceflight hardware allowing unilateral irradiation and chemical fixation in petri dishes.

To accommodate a spaceflight experiment with moss (SPM), experiment-unique equipment (EUE) was developed by engineers at Kennedy Space Center. The hardware allows sterile culture for an extended period of time in commercial petri dishes, lateral illumination of each culture with light of a specific wavelength (660 nm; other wavelengths are possible) and a range of intensities (0.05-5 micromoles photons m-2 s-1), incubation in complete darkness, and chemical fixation to terminate the experiment under conditions of microgravity. The use of a fixative required triple containment to protect the astronaut crew. An external panel on the experiment container allowed the timing of illumination and fixation to be controlled by the crew. Light quality is provided by light emitting diodes (LEDs) that are located in the lid of the outer container, the BRIC (Biological Research In Canisters)-LED. Each canister accommodates 6 Petri Dish Fixation Units (PDFUs), and each PDFU holds one 6 cm petri dish. All components are autoclavable. LED illumination is piped through a transparent glass rod. Each PDFU contains fixative in a reservoir that is released by the depression of an actuator. This hardware performed well during its first flight, the 16-day STS-87 mission in Nov./Dec., 1997 as part of the Collaborative USA and Ukrainian Experiment (CUE). It supported vigorous and sterile moss growth, cells were maintained in position and were well-fixed, and there was a vigorous and consistent response to light. Although here used for moss, in future flight experiments this unique new hardware can be used for many types of organisms normally grown in petri dishes, with or without a requirement for illumination.

Bryopsida↗
PubMed1999

Apolipoprotein E-varepsilon4 frequency in deficit schizophrenia.

The apolipoprotein E (ApoE) genotype has been found to affect the expression of several neuropsychiatric disorders. We determined ApoE genotype frequencies and their relationship to primary negative symptoms in 61 non-deficit and 45 deficit schizophrenic patients, and compared them with 98 control subjects. No difference was observed when genotype or allele frequencies were compared between the three groups. Our data do not support a role for ApoE in the phenotypic expression of schizophrenia.

Adult↗
PubMed1999

Prevalence and occupational covariates of mood, anxiety disorders, and alcohol dependence in a French ancillary staff population.

The aim of this study was to confirm the high prevalence of three frequent psychiatric disorders : anxiety, depressive illnesses, and alcohol dependence among ancillary staff, and to examine for occupational risk factors. Two hundred and forty-six women were randomly selected from the ancillary staff of the regional hospital centre of Bordeaux, and 186 subjects were interviewed between June 1996 and October 1997. First, a self-administrated questionnaire was completed concerning socio-economic status, lifestyle, health, and working conditions. Second, the two sections of the composite international diagnosis interview (CIDI), devoted to explore anxiety and depression, and the short Michigan alcoholism screening test (S-MAST) were used. Mean age of the subjects was 40.8 years (SD = 8.3 years). During the year preceding the interview, 77 (42.5%) subjects had stopped their job because of illness. Prevalence of the psychiatric disorders studied was 33.9% (95% confidence interval, 27.1-40.7%). These disorders were related to sickness absence. This is why the use of drugs raises questions for work physicians. Two protective factors associated against depression in logistic regression analysis were found : training at the time of employment, and the task 'cleaning sickroom'. A high prevalence of psychiatric disorders was confirmed and occupational risk factors for the prevalence of increased psychiatric disorders were isolated that could have practical consequences, such as for the training at time of employment.

Adult↗
PubMed1999

Mechanisms of insecticide resistance in the aphid Nasonovia ribisnigri (Mosley) (Homoptera: Aphididae) from France.

Nasonovia ribisnigri, a main pest of salad crops, has developed resistance to various insecticides in southern France, including the carbamate pirimicarb and the cyclodiene endosulfan, two insecticides widely used to control this aphid. Here we have investigated the mechanisms of resistance to these two insecticides by studying cross-resistance, synergism, activity of detoxifying enzymes, and possible modifications of the target proteins. Resistance to pirimicarb was shown to be mainly due to a decreased sensitivity of the target acetylcholinesterase; this modification conferred also, resistance to propoxur but not to methomyl and the two tested organophosphates (acephate and paraoxon). Endosulfan resistance was associated with a moderate level of resistance to dieldrin, and resistance to both insecticides was due, in part, to increased detoxification by glutathione S-transferases (GST). The endosulfan resistant strain displayed the same amino acid at position 302 of the Rdl gene (GABA receptor) as susceptible aphids (e.g. Ala), indicating that the Ala to Ser (or to Gly) mutation observed among dieldrin resistant strains of other insect species was not present.

Animals↗
PubMed1999

Structural conservation of the transposon Tam3 family in Antirrhinum majus and estimation of the number of copies able to transpose.

We have investigated the organization of the transposon Tam3 family in Antirrhinum majus. Genomic hybridization experiments and characterization of 40 independent Tam3 clones isolated from an A. majus plant revealed that the Tam3 family is quite conserved and the copy sizes are uniform. We did not find any copy with a deleted internal sequence, unlike what is usually observed in other transposons. This exceptionally conserved structure of the Tam3 family was confirmed by PCR and sequencing analyses. Sequencing analysis identified eight copies with sequences completely identical to that of the Tam3 transposase gene. These results suggested that a considerable number of autonomous Tam3 copies are present in the genome of A. majus. Among 24 copies which are surrounded by single copy regions of the genome, 14 copies are present as specific insertions in the line which we used, but absent in other lines. These copies are therefore predicted to be movable. If this ratio is the same for all Tam3 copies in a genome, then a maximum of 60% of the copies are estimated to be movable in the genome. The relatively high frequency of gene tagged by Tam3 might reflect the large number of movable copies in the genome.

Alleles↗
PubMed1999

Multifunctionality and diversity within the plant MYB-gene family.

MYB proteins constitute a diverse class of DNA-binding proteins of particular importance in transcriptional regulation in plants. Members are characterised by having a structurally conserved DNA-binding domain, the MYB domain. Different categories of MYB proteins can be identified depending on the number of imperfect repeats of the MYB domain they contain. It is likely that single MYB-domain proteins, a class of expanding importance in plants, bind DNA in a different way than two-repeat or three-repeat MYB proteins, and these groups are therefore likely to have different functions. The two-repeat (R2R3) MYB family is the largest family characterised in plants, and there are estimated to be over 100 members in Arabidopsis. Functions of MYB proteins in plants include regulation of secondary metabolism, control of cellular morphogenesis and regulation of meristem formation and the cell cycle. Although functional similarities exist between R2R3 MYB proteins that are closely related structurally, there are significant differences in the ways very similar proteins function in different species and also within the same organism. Therefore, despite the large number of R2R3 MYB proteins in plants, it is unlikely that many are precisely redundant in their functions, but more likely that they share overlapping functions.

Arabidopsis Proteins↗
PubMed1999

Excretion of lidocaine and bupivacaine in breast milk following epidural anesthesia for cesarean delivery.

BACKGROUND: There is a lack of information and knowledge about the practical importance of even low concentrations of the excretion of local anesthetics into breast milk, particularly concerning bupivacaine. The present work aims to confirm, under practical clinical conditions of admission of parturients, the passage of local anesthetics (lidocaine and bupivacaine) into breast milk after an epidural anesthesia. METHODS: Twenty-seven pregnant women admitted for cesarean delivery received epidural anesthesia with 0.5% bupivacaine and 2% lidocaine. Blood and milk samples were simultaneously collected at 2, 6 and 12 h after the beginning of the epidural infusion. Lidocaine, bupivacaine and its main metabolite, pipecolylxylidide (PPX), were determined in serum and milk by a gas-liquid chromatographic technique. APGAR scores were systematically performed at delivery and a clinical examination was done 24 h after delivery. RESULTS: Our data indicate that lidocaine and bupivacaine as well as PPX are excreted into breast milk. The milk/serum ratio based upon area under the curve values were 1.07 +/- 0.82, 0.34 +/- 0.24 and 1.37 +/- 0.61 mean +/- SD for lidocaine, bupivacaine and PPX, respectively. Most of the newborns had a maximal APGAR score. Our study does not reveal any adverse reactions related to the excretion of local anesthetics into breast milk. CONCLUSION: This study documents the magnitude of excreted lidocaine, bupivacaine and PPX in breast milk, and indicates that the use of both lidocaine and bupivacaine for epidural anaesthesia is safe with regard to breast-feeding.

Adult↗
PubMed1999

Passive expiratory flow-volume curve is not an accurate method to measure the respiratory time constant in rabbits.

BACKGROUND: In mechanically ventilated patients, inspiration is forced by an externally applied positive pressure whereas expiration remains passive and depends on the time constant of the total respiratory system (tau), which constitutes an important determinant of mechanical ventilation. The end-inspiratory occlusion technique is one of the easiest methods to obtain tau values in ventilated patients, especially infants, but its accuracy is not well established. The aim of this study was to compare in anesthetized, paralyzed rabbits tau values given by the end-inspiratory occlusion technique (tau(rs)) to tau values obtained by references methods for measurements (i.e. the product of static lung compliance by airway resistance: tau(ref)) during carbachol-induced bronchospasm eliciting marked modifications of the respiratory mechanics. METHODS: Comparisons were made in the basal state and after carbachol-induced bronchoconstriction in seven New Zealand adult rabbits. This procedure resulted in a wide range of expiratory time constants. A pneumotachograph was used to measure expiratory flow and volume before and after end-inspiratory occlusion. The slope of the flow volume curve gave tau(rs). Then tau(rs) was compared with tau(ref) (which ranged from 0.30 to 1.96 s). RESULTS: Statistical analysis revealed a weak correlation between the two methods, and a size-dependent bias of tau(rs) measurements. CONCLUSIONS: The end-inspiratory occlusion technique leads to a systemic bias in measurements of respiratory time constant, especially when the resistance of the respiratory system is elevated.

Airway Resistance↗
PubMed1999

Project DARE: no effects at 10-year follow-up.

The present study examined the impact of Project DARE (Drug Abuse Resistance Education), a widespread drug-prevention program, 10 years after administration. A total of 1,002 individuals who in 6th grade had either received DARE or a standard drug-education curriculum, were reevaluated at age 20. Few differences were found between the 2 groups in terms of actual drug use, drug attitudes, or self-esteem, and in no case did the DARE group have a more successful outcome than the comparison group. Possible reasons why DARE remains so popular, despite the lack of documented efficacy, are offered.

Adolescent↗