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Biomedical subjects

O Martin

Publications and source records attributed to O Martin.

At least 19 recordsLinked to original sources
PubMed2006

www.fevertravel.ch: an online study prototype to evaluate the safety and feasibility of computerized guidelines for fever in returning travellers and migrants.

Following the paper publication of practice guidelines for the management of febrile patients returning from the tropics, we constructed a consultation website that comprises a decision chart and specific diagnostic features providing medical diagnostic assistance to primary care physicians. We then integrated a research component to evaluate the implementation of these computerized guidelines. This study website has the same interface as the consultation website. In addition, one is able to record: (i) the pathway followed by the physician through the decision chart, (ii) the diagnostic tests performed, (iii) the initial and final diagnoses as well as outcome and (iv) reasons for non-adherence when the physician diverges from the proposed attitude. We believe that Internet technology is a powerful medium to reach physicians of different horizons in their own environment, and could prove to be an effective research tool to disseminate practice guidelines and evaluate their appropriateness. Here we describe the design, content, architecture and system implementation of this interactive study prototype aimed at integrating operational research in primary care practice.

Emigration and Immigration↗
PubMed2006

Necrotizing gastritis due to Bacillus cereus in an immunocompromised patient.

Bacillus cereus is increasingly being acknowledged as a serious bacterial pathogen in immunocompromised patients. We present a case of acute necrotizing gastritis caused by B. cereus in a 37-year-old woman with acute myeloblastic leukemia, who recovered following total parenteral nutrition and treatment with imipenem and vancomycin. B. cereus was isolated from gastric mucosa and blood cultures. Up to now, no case of acute necrotizing gastritis due to this organism has been reported.

Adult↗
PubMed2004

Fatal Microascus trigonosporus (anamorph Scopulariopsis) pneumonia in a bone marrow transplant recipient.

Over the past decade, an increasing number of opportunistic mycelial fungal infections have been reported in immunocompromised patients. Presented here is the first reported case of Microascus trigonosporus pneumonia, which occurred in a 24-year-old-man with a history of allogenic bone marrow transplantation with graft-versus-host disease. Despite the administration of effective antifungal treatment, the patient died after uncontrollable respiratory failure and multiorgan failure developed. This report confirms the results of previous studies that suggested a very poor outcome for bone marrow transplant recipients with non-Aspergillus mould infections.

Adult↗
PubMed2004

Delayed toxicity following acute ingestion of valpromide.

As valpromide is a prodrug of valproic acid (valproate), the clinical presentation of overdoses with either valpromide or valproate sodium is generally considered similar. Whereas plasma peak levels and signs of central nervous system depression occur within a few hours after the acute ingestion of regular-release forms of valproate sodium, delayed toxicity and time to peak levels following valpromide ingestion can be seen as shown by the three reported cases. They were initially considered as mild because patients presented with no or only moderate symptoms and serum valproate levels were below or at therapeutic levels on admission more than 3 hours post-ingestion in two of the three patients. Serum valproate levels were not monitored until marked deterioration more than 10 hours after ingestion. At the time of deterioration, serum valproate was at toxic level in the three reported cases. Therefore, large intake of valpromide should be closely monitored because no or moderate symptoms together with low plasma levels in the first few hours after ingestion do not exclude a subsequent severe intoxication. Despite the usual favourable outcome and the poor correlation between plasma levels and toxic symptoms, patients should not be discharged until plasma levels are documented to remain at low levels for at least 10 hours after the ingestion of valpromide and the patient asymptomatic.

Adult↗
PubMed2002

Effects of high intensity pulsed electric field and thermal treatments on a lipase from Pseudomonas fluorescens.

Milk and dairy products may contain microorganisms capable of secreting lipases that cause sensory defects and technological problems in the dairy industry. In this study, the effects of thermal and high-intensity pulsed electric field (HIPEF) treatments on an extracellular lipase from Pseudomonas fluorescens, suspended in a simulated skim milk ultrafiltrate (SMUF) have been evaluated. Heat treatments applied were up to 30 min from 50 to 90 degrees C. HIPEF treatments were carried out using pilot plant facilities in a batch or continuous flow mode, where treatment chambers consisted of parallel and coaxial configuration, respectively. Samples were subjected to up to 80 pulses at electric field intensities ranging from 16.4 to 37.3 kV/cm. This resulted in a lipase that was quite resistant to heat and also to HIPEF. High (75 degrees C-15 s) and low pasteurization treatments (63 degrees C-30 min) led to inactivations of 5 and 20%, respectively. Using the batch-mode HIPEF equipment, a 62.1% maximum activity depletion was achieved after 80 pulses at 27.4 kV/cm. However, when HIPEF treatments were applied in the continuous flow mode, an inactivation rate of just 13% was achieved, after applying 80 pulses at 37.3 kV/cm and 3.5 Hz. The results of both heat and HIPEF treatments on enzyme inactivation were adjusted with good agreement to a first-order kinetic model (R2 > 62.3%).

Animals↗
PubMed2002

Metaanalysis of input/output kinetics in lactating dairy cows.

The kinetics of dry matter intake, raw milk yield, milk fat yield, and body weight of 140 treatment groups of cows reported in 37 articles published between 1959 and 1999 were collected in a database. The majority of these experiments were performed with Holstein-Friesian cows (primiparous: n = 51, multiparous: n = 89). Animals were fed with forages and concentrates, offered separately (n = 98) or as a total mixed ration (n = 42). Empty body weight was calculated assuming that an increase of 1 kg in dry matter intake corresponded to an increase of 4 kg in gastrointestinal tract content. Each kinetic, denoted Y, was fitted with the model proposed by Grossman (1999) for raw milk yield. This model allowed the partitioning of the kinetic into three stages (early, middle, and late stages of lactation), each characterized by its own linear tendency. Kinetics were therefore summarized with parameter estimates of the model: the plateau value of Y in middle stage, the slopes of Y in early and late stages, and the weeks of start and end of the middle stage. The following additional variables were also calculated: the total increase of Y in early stage, the extrapolated value of Y at calving, and the persistency of Y defined as the duration of the middle stage. Variability of these parameters for each kinetic across treatment groups was examined through mixed models including the year of publication as covariate, parity as a fixed between-group factor, and trial as a random factor. Correlations between parameters within a Y-kinetic and between different Y-kinetics were calculated by parity group and feed allocation system. Finally we propose predictive models which emphasized (1) the effect of empty body weight at calving on the depletion of empty body weight in early lactation, (2) the incidence of the kinetic of dry matter intake on the kinetic of raw milk yield in middle and late stages of lactation, and (3) the relationships between the kinetics of raw milk yield and milk fat yield in middle and late stages of lactation.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Validation and comparison of analytical methods based on the release of p-nitrophenol to determine lipase activity in milk.

Three methods of determining lipase activity were optimized, validated, and compared using skim and whole milk. A chromogenic ester (p-nitrophenyl caprylate) was used in all to quantify the enzyme activity through the release of p-nitrophenol. It was measured colorimetrically (method A) or spectrophotometrically (methods B and C) with a clarifying reagent to render the samples measurable. Methods B and C differed because an inhibiting mixture was used in the latter method to better stop the enzymatic reaction. All the methods were reliable; they were linear in the range of 0 to 300 mU/ml of the enzyme, and the least detection and quantification limits were 9.31 and 31.03 mU/ml of lipase, respectively. Precision, measured as relative standard deviation, was between 1.52 and 4.94%, and mean recoveries ranged between 81 and 90%. Linearity, sensitivity, and accuracy were significantly different among the methods. Methods B and C had better linearity and sensitivity than method A, and the most accurate results were obtained with methods A and B in skim milk. Sensitivity was influenced by the fat content of the samples. On the other hand, the content of lipase did not influence the reliability of any method. Although, all of the methods were useful for routine analysis of quality control of milk, method B was most reliable. Moreover, it would be the method of choice because it was easier and less costly than the other methods.

Animals↗
PubMed2000

Pointing to a target from an upright position in human: tuning of postural responses when there is target uncertainty.

Human subjects performed, from a standing position, rapid hand pointings to visual targets located within or beyond the prehension space. To examine the interaction between posture and the goal-directed movement we introduced a visual double-step perturbation requiring a reprogramming of the hand movement. Trials directed towards the same spatial goal but differentiated only by the likeliness of a visual double-step were compared. The hand kinematics was not affected by the uncertainty of the visual perturbation; an increased trunk bending, however, was observed. This suggests that uncertainty constraints are integrated in a predictive manner for the optimal coordination of the hand and postural control systems.

Adult↗
PubMed1999

Deafferentation and pointing with visual double-step perturbations.

The capability of reprogramming movement responses following changes in the visual goal has been studied through the double-step paradigm. These studies have shown that: (a) continuous internal feedback-loops correct unconsciously the dynamic errors throughout the movement; (b) proprioceptive information and/or the efference copy have a privileged status among central processes, insuring on-line regulation of the initial motor commands; and (c) generation of the motor program starts after target presentation, and is continuously updated in the direction of the current internal representation of the target, at least until the onset of hand movement. This main corrective process of the initial program appears to be basically independent of visual reafference from the moving hand. However, the agreement with the possibility of a visuomotor loop, based on the comparison of the new updated representation of the target position and on the information from the moving hand, has not determined whether the correcting process is proprioceptive feedback dependent, or whether internal feedback-loops (efferent copies) are responsible for quick corrections of unfolding motor responses. To answer this question, the present experiment investigated the pointing behavior of a deafferented subject, using a double-step paradigm under various conditions of visual feedback and movement initiation. Overall, the present study (a) clearly showed the capacity of the motor system to modify and correct erroneous trajectories on the mere basis of internal feedback-loops and (b) emphasized the crucial role played by the target jump/arm triggering delay and the importance of the eye efferent copy for providing information about the spatial goal of the movement.

Afferent Pathways↗
PubMed1999

Role of the feedforward command and reafferent information in the coordination of a passing prehension task.

The performances of a deafferented patient and five control subjects have been studied during a self-driven passing task in which one hand has to grasp an object transported by the other hand and in a unimanual reach-to-grasp task. The kinematics of the reach and grasp components and the scaling of the grip aperture recorded for the self-driven passing task were very similar in controls and the deafferented subject (GL). In contrast, for the unimanual task when vision was absent, GL's coordination between reaching and grasping was delayed in space and time compared with the control subjects. In addition, frequent reopening of the grip was observed in GL during the final closure phase of the unimanual prehension task. These results support the notion that afferent proprioceptive information resulting from the reaching movement - which seemed to be used to coordinate reaching and grasping commands in the unimanual task - is no longer necessary in the self-induced passing task. Finally, for the externally driven passing task, when the object was passively transported by the experimenter, the coordination was consistently modified in all subjects; grip aperture onset was delayed, thus asserting a specific contribution of the central command or feedforward mechanisms into the anticipation of the grasp onset observed in the self-driven passing task. The origin and nature of the information necessary for building up the feedforward mechanisms remains to be elucidated.

Adult↗
PubMed1998

Corrective loops involved in fast aiming movements: effect of task and environment.

In daily living, we continuously interact with our environment. This environment is rarely stable and living beings show remarkable adaptive capacities. When we reach for an object, it is necessary to localize the position of this object with respect to our own body before programming an adequate arm movement. If the target remains stable, the programmed movement brings the hand near the target. However, what happens when the target suddenly jumps to another position in space? The aim of this work was to investigate how rapid aiming movements are corrected when the target is displaced close to movement onset. Our results reveal that rapid movements can be modified and that the efficiency of trajectory amendments vary according to task (directional or direction/amplitude pointings) and environment (structured or darkness). We were most interested in the specific role played by peripheral and/or central feedback information (efferent copy) in the control of aiming movements. The results suggest that the two types of loops are complementary in movement regulation. However, their predominance varies according to the nature of the task at hand.

Adaptation, Physiological↗
PubMed1998

The safety sphincterotome: the device, the technique and preliminary results.

BACKGROUND AND STUDY AIMS: Endoscopic sphincterotomy is a widely used and safe procedure for the management of common bile duct stones, but little attention has been paid to the design of the sphincterotome and its influence upon risk of sphincterotomy. This study was undertaken to evaluate a sphincterotome, designed to incorporate known and original aspects which may contribute to safety. PATIENTS AND METHODS: 144 patients with bile duct stones were evaluated in an open prospective study of the use of the sphincterotome in performing endoscopic sphincterotomy. Evaluation included post-sphincterotomy complications, 30-day morbidity and mortality and effective duct clearance. RESULTS: Only one complication (0.7%) occurred in the group of 144 patients. Duct clearance of stones was ultimately achieved in 94%. CONCLUSIONS: Whilst more experience is necessary using the sphincterotome in the manner described, the absence of significant complications in all but one patient appears to support the philosophy behind the design of the sphincterotome.

Adult↗