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Biomedical subjects

D Robert

Publications and source records attributed to D Robert.

At least 37 records · Page 2Linked to original sources
PubMed2004

Context-dependent stimulus presentation to freely moving animals in 3D.

The presentation of controllable, dynamic sensory stimuli provides a powerful experimental paradigm, which has been extensively applied to explore sensory processing in walking and tethered flying insects. Recent advances in computer hardware and software technology provide the opportunity to track the 3D flight path of free-flying insects and process these data in real-time, opening up the possibility to present dynamic stimuli to free-flying animals. To accommodate for the increased complexity relating to 3D space, we partitioned experimental design, real-time data acquisition and stimulus control into multiple self-contained modules. 3D experimental scenarios were created in a stand-alone application by forging multiple 3D space-stimulus relationships. The use of dynamic cues is illustrated by an experiment, in which dynamic acoustic cues were presented to a free-flying parasitoid fly in a large 3D environment. The combination of loosely coupled modules provides robust and flexible solutions, allowing new paradigms to be readily implemented based on existing technologies. We demonstrate this with a test system that displayed a complex visual stimulus, controlled in real-time by the 2D position and orientation of a test object. The presented methods are applicable in a variety of novel experimental paradigms, including learning paradigms, for various sensory modalities in walking, swimming and flying animals.

Animals↗
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

The relation between preprocedural C-reactive protein levels and early and late complications in patients with acute myocardial infarction undergoing interventional coronary angioplasty.

BACKGROUND: Inflammation is an important feature of arteriosclerotic disease, and the vulnerability of coronary plaques in acute myocardial infarction (AMI) may be related to the levels of serum C-reactive proteins (CRP). While some risk factors for early and late complications have been suggested, an accurate and definitive preprocedural risk stratification of patients undergoing percutaneous transluminal coronary angioplasty (PTCA) is still lacking. HYPOTHESIS: The study was undertaken to investigate whether early and late complications after PTCA could be predicted by evaluation of baseline serum CRP levels in patients with AMI. METHODS: Levels of serum CRP were measured in a total of 230 patients with AMI undergoing PTCA and provisional stent. They were divided into two groups: Group 1 (n = 48) with elevated CRP levels (> or = 5 mg/l) and Group 2 (n = 182) with normal CRP levels (< 5 mg/l). RESULTS: There were no significant differences in baseline clinical, angiographic, and procedural characteristics between the two groups. However, the incidence of in-hospital adverse coronary events (reinfarction, coronary reocclusion, target vessel revascularization, and death) and severe left ventricular dysfunction was significantly higher in Group 1 (18.3 vs. 6.1%, p < 0.05 and 20.9 vs. 6.1%, p < 0.05, respectively). In addition, bailout stenting was performed more frequently in Group 1 than in Group 2 (60.4 vs. 36.3%, p < 0.005). No significant late complications were noted. The serum levels of CRP were the only independent predictors of early adverse events. CONCLUSIONS: Preprocedural serum CRP level might be considered a powerful predictor of early but not late complications in patients undergoing PTCA/stent procedures.

Aged↗
PubMed2004

Surgical implications of sentinel node with micrometastatic disease in invasive breast cancer.

AIM: To assess the rate of positive axillary clearance (AC) when the sentinel node biopsy (SNB) contains micrometastatic disease in invasive breast cancer and to evaluate the factors that could predict positivity. PATIENTS AND METHODS: This is a prospective study carried out on 542 successive women undergoing SNB for unifocal T0-T1 N0 invasive breast cancer without previous treatment. RESULTS: Five hundred and twenty-five sentinel nodes (SN) were found, 142 contained metastases. Fifty-five of the positive SN contained micrometastatic disease only. Of them, 40 patients underwent completion of AC. Six out of 40 patients who had micrometastatic SN had a positive AC, five for micrometastasis between 0.2 and 2 mm (5/34), one for isolated cells in the SN (1/6). None of the studied factors (age, histological tumour size, histological grade, estradiol receptor (ER), histological tumour type, size and method of micrometastasis detection) could significantly predict the status of the AC. CONCLUSION: As long as the results of ongoing prospective randomised studies are unknown, it remains necessary to perform AC when the SNB contains micrometastatic disease, whatever the size or the detection mode of the metastasis.

Adult↗
PubMed2003

Motion generation by Drosophila mechanosensory neurons.

In Drosophila melanogaster, hearing is supported by mechanosensory neurons transducing sound-induced vibrations of the antenna. It is shown here that these neurons additionally generate motions that mechanically drive the antenna and tune it to relevant sounds. Motion generation in the Drosophila auditory system is betrayed by the auditory mechanics; the antenna of the fly nonlinearly alters its tuning as stimulus intensity declines and oscillates spontaneously in the absence of sound. The susceptibility of auditory motion generation to mechanosensory mutations shows that motion is generated by mechanosensory neurons. Motion generation depends on molecular components of the mechanosensory transduction machinery (NompA, NompC, Btv, and TilB), apparently involving mechanical activity of ciliated dendrites and microtubule-dependent motors. Hence, in analogy to vertebrate hair cells, the mechanosensory neurons of the fly serve dual, transducing, and actuating roles, documenting a striking functional parallel between the vertebrate cochlea and the ears of Drosophila.

Animals↗
PubMed2003

C-reactive protein levels and arterial abnormalities in the offspring of patients with premature myocardial infarction.

AIMS: To determine whether high C-reactive protein (CRP) levels and increased intima-media thickness of the common carotid arteries are coexistent in adolescents and young adults with a family history (FH) of premature myocardial infarction (MI). METHODS: 50 healthy young subjects whose parents had had premature MI and 50 control matched subjects were enrolled in the study. CRP levels and the intima-media thickness of the distal common carotid arteries were evaluated in all subjects. RESULTS: As compared with the control subjects, the offspring of patients with premature MI had a higher CRP concentration (mean +/- SD 8.8 +/- 2.6 versus 3.9 +/- 0.6 mg/l, p < 0.02) and greater intima-media thickness of the common carotid arteries (values for combined sides, mean +/- SD 0.48 +/- 0.02 versus 0.43 +/- 0.02 mm, p < 0.03). CONCLUSION: High serum levels of CRP and arterial structural changes are coexistent at an early age in subjects with an FH of premature MI.

Adolescent↗
PubMed2002

Evaluation of ventilators used during transport of ICU patients -- a bench study.

OBJECTIVES: To evaluate portable ventilators. DESIGN AND SETTINGS: Bench study. MATERIALS AND METHODS: Five portable ventilators used for transporting ICU patients [Osiris 1, (ventilator a), Osiris 2, (ventilator b), Oxylog 1000, (ventilator c), Oxylog 2000, (ventilator d), AXR1a, (ventilator e)] and three ICU ventilators which can be used for this purpose [Horus, (ventilator f), T-Bird, (ventilator g), and SV 300, (ventilator h)] were compared using a test lung regarding: 1) their capability to maintain set tidal volumes (V(T)) of 300 ml, 500 ml, and 800 ml under a normal condition A [resistance (R) 5 cmH(2)O/l/s and compliance (C) 100 ml/cmH(2)0] and two abnormal conditions B (R 20-C 30) and C (R 50-C 100); 2) trapped volume (expired V(T)relative to inspired V(T)at 0.7 s, 1 s, and 1.4 s), an estimate of the expiratory resistance of both circuit and valve; and 3) the triggering system assessed from the measurements of Delta t, Delta P for two inspiratory efforts at a PEEP of 0 cmH(2)0 and 5 cmH(2)0 in ventilators b, d, f, g, and h. Flow and airway pressure were measured with an independent physiologic recording system. RESULTS: 1) V(T). For ventilators a-h, the mean+/-SD changes of a set V(T)of 300 ml were -2.6+/-0.2%, -9.7+/-0.2%, 0+/-0%, -6.1+/-0.2%, 1.0+/-0.3%, -2.1+/-1.7%, 0.3+/-0%, and -1.3+/-0.1% ( P<0.001), respectively, during condition B relative to A. Similar results were obtained for a V(T)of 500 ml and 800 ml and during condition C relative to A; 2) Trapped volume. For ventilators a-h, trapped volume averaged 1+/-1%, 20+/-0%, 30+/-0.4%, 20+/-1%, 1+/-0%, 19+/-0%, 15+/-0%, and 14+/-0% at 0.7 s ( P <0.001) and 0.6+/-0%, 5+/-0%, 0.5+/-0%, 0+/-0%%, 0+/-0%, 0.6+/-0%, 0+/-0%, and 0+/-0% at 1.4 s ( P=NS); and 3) the triggering system of Oxylog 2000 was poor whereas it was of good quality for Horus, T-Bird, SV 300, and Osiris 2. CONCLUSIONS: The small portable ventilators presently investigated varied between each other and were less accurate than ICU ventilators.

Analysis of Variance↗
PubMed2002

atonal is required for exoskeletal joint formation in the Drosophila auditory system.

Hearing relies on the delicate arrangement of mechanoreceptor neurones and an acoustomechanical interface. The concerted action of these neural and non-neural components is essential to audition, raising the question of whether they also develop in a concerted way. Drosophila hears with its antennae. A specialized antennal joint allows the distal part of the antenna to vibrate in response to sound and, thus, to serve as the sound receiver. This receiver's vibration is transduced by a chordotonal sense organ (CHO) that is closely associated with the joint. Here, we report that atonal (ato), the proneural gene for CHOs, is required for the formation of this antennal joint. Biophysical measurements in hemi- and homozygous ato(1) mutant flies show that, in addition to eliminating the auditory CHO, loss of ato function makes the antennal receiver insensitive to sound, impairing its auditory function. Anatomically, the cause for this mechanical effect resides in the deprivation of mobile exoskeletal joint structures. Hence, ato, the homologue of mouse Math1, is required for the formation of both the auditory CHO and joint, providing a genetic link between the very neural and exoskeletal components that together transform fly antennae into ears.

Acoustic Stimulation↗
PubMed2002

Acoustic sensitivity of fly antennae.

The vast majority of higher flies - the brachycerans - is endowed with strikingly similar antennal morphologies and elaborate antennal mechanosensory organs. Thus far, however, the function of audition has been attributed only to the antennae of Drosophilid and Tephritid flies. Antennal mechanical sensitivity to sound is now documented in a broad range of fly species. These results highlight the wide occurrence of audition in as many as 120,000 species of higher Diptera. Antenna-based audition, as defined by the capacity of sensing the mechanical vibrations of the antenna in response to sound, thus appears to constitute an ubiquitous sensory capacity among higher flies. Functionally, antennal hearing can be used in the contexts of intraspecific acoustic signalling, flight control, and putatively close-range echolocation.

Journal Article↗
PubMed2002

[Outcome of adult patients with cystic fibrosis admitted to intensive care with respiratory failure: the role of non-invasive ventilation].

Recourse to mechanical ventilation may prove necessary in adult patients with cystic fibrosis who have reached the stage of severe respiratory insufficiency. We report the experience of an intensive care service using non-invasive ventilation (NIV) as the first step in the management of acute respiratory failure in these patients. The records of 16 patients with cystic fibrosis presenting with acute respiratory failure and treated with NIV were analysed retrospectively. The characteristics of the group were: mean age 26.9 +/- 9.5 years; mean FEV1 21.5 +/- 10.4% predicted; mean body mass index 16.8 +/- 2.1; mean Pa CO(2) on admission 66 +/- 15 mm Hg. The mean duration of NIV in the ICU was 10 +/- 7 days. Eight patients (50%) died after having been intubated on account of failure of NIV. The eight survivors were discharged home with long-term NIV (mean duration 235 +/- 158 days). Six of them have received a lung transplant. The mode of onset of respiratory failure was an important prognostic factor: a rapid onset (<7 days) was invariably associated with death, on the other hand a gradual deterioration (> 7 days) was noted in the eight patients able to leave the ICU. In conclusion NIV may be regarded as the treatment of choice in patients with cystic fibrosis admitted to ICU with respiratory failure. In the case of persistent hypercapnia after the acute episode long-term NIV may keep them stable while awaiting lung transplantation.

Adult↗
PubMed2002

[Treatment of obstructive sleep apnea syndrome with mandibular advancement appliances].

Mandibular advancement device provide a therapeutic option for obstructive sleep apnea syndrome (OSAS). Clinical improvement has been proven in the different available studies, mainly on nocturnal respiratory events and quality of sleep. Less snoring have been noted by bed partners and objective studies have demonstrated a decrease in snoring frequency and intensity. The effects of these appliances on upper airways resistance syndrome is not yet well documented. The significant clinical improvement is secondary to the decrease in the occurrence of apneas and hypopneas. Polysomnographic improvement criteria with an apnea hypopnea index less than 10 per hour has been noted in certain cases, although no improvement or even worsening was noted in other cases. Sleep architecture has also changed in these patients, with a decrease in the time spent in stages 1 and 2, and an increase in the time spent in stages 3, 4 and rapid eye movement sleep. Micro-arousals are also reduced in number. Somnolence and loss of attention are improved; these have been evaluated subjectively or by a well known and approved somnolence scale. In some cases a test for vigilance was done. Our results are identical to those published in the different studies concerning respiratory events and sleep architecture.

Airway Resistance↗
PubMed2002

[Non-linear model of glottic vibration. Potential clinical implications].

Glottic vibration is governed by a certain number of physical laws which in general correspond, as far as myo-elastic theory is concerned, with the laws of passive vibration of an elastic body under the influence of the expired air. Some of these laws are non-linear, especially those that deal with the exchange of energy between the expired air and the vocal folds. This non-linearity is specially important when it comes to the key concepts of the phonatory threshold and the passive synchronisation of the vocal cords. Based on their experimental work, which has been presented previously, the authors propose a mixed model, which is both linear and non-linear, like the oscillators of Van der Pool. This model is known as Slip-Stick.

Glottis↗