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Biomedical subjects

F Stephan

Publications and source records attributed to F Stephan.

At least 19 recordsLinked to original sources
PubMed2002

Generation of GW radiation pulses from a VUV free-electron laser operating in the femtosecond regime.

Experimental results are presented from vacuum-ultraviolet free-electron laser (FEL) operating in the self-amplified spontaneous emission (SASE) mode. The generation of ultrashort radiation pulses became possible due to specific tailoring of the bunch charge distribution. A complete characterization of the linear and nonlinear modes of the SASE FEL operation was performed. At saturation the FEL produces ultrashort pulses (30-100 fs FWHM) with a peak radiation power in the GW level and with full transverse coherence. The wavelength was tuned in the range of 95-105 nm.

Journal Article↗
PubMed2002

[Perforating skin ulcers occurring in an adult with dermatomyositis].

BACKGROUND: Skin ulcerations are rarely reported in dermatomyositis of the adult. We report on a case of perforating ulcers resistant to classical treatments in a woman with dermatomyositis. CASE REPORT: A 34 year-old woman, treated for typical dermatomyositis, developed a few weeks after starting her treatment, multiple perforating skin ulcers on her shoulders, elbows and wrists though general signs had completely disappeared. In spite of the increase in oral steroids, the patient presented again with worsened lesions and a new perforating ulcer on the hand which lead to the breaking of a tendon. She underwent hand surgery and was also treated with a bolus of steroids IV (1 g daily during 3 days), followed by oral steroids, IM methotrexate and antimalarial drugs. The lesions healed completely after one month, with no atrophy. DISCUSSION: Skin ulcers are rarely described in dermatomyosites of the adult and are associated with underlying vasculitis and bad prognosis. Our case is remarkable by the absence of vasculitis, a very slow cure requiring aggressive treatment and excellent prognosis after three years of follow-up.

Adult↗
PubMed2000

First observation of self-amplified spontaneous emission in a free-electron laser at 109 nm wavelength

We present the first observation of self-amplified spontaneous emission (SASE) in a free-electron laser (FEL) in the vacuum ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approximately 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width, and intensity fluctuations, are all consistent with the present models for SASE FELs.

Journal Article↗
PubMed1999

Clinical practice guidelines for the use of albumin: results of a drug use evaluation in a Paris hospital. Tenon Hospital Paris.

Clinical practice guidelines on the prescription of albumin were instituted in our hospital according to a method which combined a review of the medical literature with experts points of view. Their broadcasting was based upon a daily patient-specific decision support which was well-documented by the prescribing physician. The method for assessing the impact was a six month analysis of the discrepancies between recommendations and clinical practice. Results were a better compliance with guidelines (25.5% before and 59% after developing recommendations), a decrease 70% in grams of albumin prescribed and in use of an increase synthetic colloids, and a savings of $57,208 per year.

Blood Volume↗
PubMed1999

Effect of 7-day therapy with different doses of the proton pump inhibitor lansoprazole on the intragastric pH in healthy human subjects.

BACKGROUND: Systematic, randomized, and controlled studies on the effect of low to high doses of the proton pump inhibitor lansoprazole on intragastric acidity and plasma gastrin levels have not previously been performed. METHODS: We investigated the effect of 7-day therapy with different doses of lansoprazole (15 mg once or twice daily, 30 mg once or twice daily, and 15 mg three times daily) on intragastric acidity and meal-stimulated daytime plasma gastrin levels in 12 healthy Helicobacter pylori-negative human subjects in a randomized, double-blind, placebo-controlled, 6-way crossover study. On days 1, 2, and 7 of the study 24-h intragastric pH-metry and 12-h integrated daytime plasma gastrin determinations were done. RESULTS: Lansoprazole in a dose regimen of 1 x 30 mg/day, 3 x 15 mg/daily, and 2 x 30 mg/day significantly (P < 0.05) increased the intragastric 24-h median pH on days 1, 2, and 7 of therapy as compared with placebo. Lansoprazole in doses of 1 x 15 mg/day and 2 x 15 mg/day significantly increased the intragastric 24-h median pH on days 2 and 7 but not on day 1 of therapy. Doses of 3 x 15 mg and 2 x 30 mg lansoprazole daily significantly increased the intragastric 24-h median pH on days 2 and 7 of treatment as compared with 1 x 30 mg lansoprazole daily. Except for 1 x 15 mg lansoprazole on day 1 of therapy, all given dose regimens of lansoprazole (15-60 mg/day) significantly (P < 0.05) stimulated the 12-h integrated meal-stimulated daytime plasma gastrin response (pM x min) on days 1, 2, and 7 of therapy as compared with placebo. CONCLUSION: A dose of 1 x 30 mg/day is nearly as potent as higher dose regimens of lansoprazole. Thus it most likely is the optimum dose for therapy of gastric and duodenal peptic lesions. A dose of 1 x 15 mg lansoprazole daily is a potent inhibitor of gastric acid output and could be a therapeutic dose for prevention of peptic lesions (that is, reflux oesophagitis or ulcers).

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1999

Thrombocytopenia in critically ill surgical patients: a case-control study evaluating attributable mortality and transfusion requirements.

BACKGROUND: That thrombocytopenia results in increased mortality or transfusion requirements has not been confirmed by previous studies. We performed a case-control study in which 36 patients who developed severe thrombocytopenia of less than 50x109 platelets/l were carefully matched for the severity of underlying disease and other important variables. RESULTS: Seventeen (47%) thrombocytopenic patients died, versus 10 (28%) matched control patients who were not thrombocytopenic.Nine pairs had a discordant outcome, and in eight of these pairs the thrombocytopenic patient died (exact binomial probability 0.037). The estimated attributable mortality was 19.5% (95% confidence interval 3.2-35.8), and the estimated odds ratio was 2.7 (95% confidence interval 1.02-7.10). Thrombocytopenic patients had comparable values for severity of illness scores between day of admission and day of thrombocytopenia, in contrast with control patients who had a statistically significant decrease in severity of illness scores during the same period. Thirty (83%) of the thrombocytopenic patients required transfusion of blood products, versus 21 (58%) control patients (paired chi2 test 4.92, P < 0.04). The estimated attributable transfusion requirement was 25% (95% confidence interval 5.4-44.6), and the estimated odds ratio was 1.52 (95 confidence interval 1.05-2.20). CONCLUSION: The present study suggests that thrombocytopenia of less than 50 x 109 platelets/l may be a marker for more severe illness and increased risk of death, rather than causative, because a true causal relationship is not established. Thrombocytopenia also leads to an excess of blood product consumption.

Journal Article↗
PubMed1998

Determination of total effective vascular compliance in patients with sepsis syndrome.

Changes in capacitance vessels have important consequences on cardiac filling pressure and fluid volume distribution in patients with sepsis syndrome. Vascular compliance may be evaluated from the slope of the relationship between changes in total blood volume (deltaTBV) and changes in central venous pressure (deltaCVP) during acute volume expansion (450 ml of gelatin fluid over 6 min), i.e., from the deltaTBV/deltaCVP ratio. The mean ratio (ml x mm Hg-1 x kg-1) was 2.03 +/- 0.21 in control subjects, 1.43 +/- 0.25 in mechanically ventilated patients without sepsis syndrome, and 0.94 +/- 0.24 in mechanically ventilated patients with sepsis syndrome (p < 0.0001 versus the other two groups). Based on echocardiographic determinations, cardiac performance was constantly found within the normal range (cardiac output ranged from 5.6 +/- 1.2 to 6.7 +/- 2.0 L/min in nonseptic patients from 6.8 +/- 1.9 to 7.8 +/- 2.2 in septic patients). Effective compliance of the total vascular bed is therefore reduced in patients with sepsis syndrome, independently of the hemodynamic modifications due to mechanical ventilation.

Adolescent↗
PubMed1998

Risk factors and outcome of nosocomial infections: results of a matched case-control study of ICU patients.

Intensive-care-unit (ICU) patients are at risk for both acquiring nosocomial infection and dying, and require a high level of therapy whether infection occurs or not. The objective of the present study was to precisely define the interrelationships between underlying disease, severity of illness, therapeutic activity, and nosocomial infections in ICU patients, and their respective influences on these patients' outcome. In a 10-bed medical ICU, we conducted a case-control study with matching for initial severity of illness, with daily monitoring of severity of illness and therapeutic activity scores, and with analysis of the contribution of nosocomial infections to patients' outcomes. Forty-one cases of patients who developed nosocomial infections during a 1-yr period were paired with 41 controls without nosocomial infection according to three criteria: age (+/- 5 yr), Acute Physiology and Chronic Health Evaluation II (APACHE II) score (+/- 5 points), and duration of exposure to risk. Successful matching was achieved for 118 of 123 (96%) variables. Neurologic failure on the third day after ICU admission was the sole independent risk factor for nosocomial infection (adjusted odds ratio [OR]: 1.34; 95% confidence interval [CI]: 1.09 to 1.64; p = 0.007). Unlike control patients, case patients showed no clinical improvement and required a high level of therapeutic activity between ICU admission and the day of infection. Mortality attributable to nosocomial infection was 44%. Excess length of stay and duration of antibiotic treatment attributable to nosocomial infection were 14 d and 10 d, respectively. Attributable therapeutic activity as measured with the Therapeutic Intervention Scoring System (TISS) and Omega score was 368 and 233 points, respectively. Such consequences were observed in patients who developed multiple infections. These findings suggest that a persistent high level of therapeutic activity and persistent impaired consciousness are risk factors for nosocomial infections in ICU patients. These infections are responsible for excess mortality, prolongation of stay, and excess therapeutic activity resulting in important cost overruns for health-care systems.

APACHE↗
PubMed1997

[Prevention of acquired pneumonia during artificial ventilation (excluding the use of anti-infectious agents)].

Nosocomial pneumonia remains a serious complication which occurs in patients who are artificially ventilated; as neither frequency nor important sequelae have altered recently inspite of the progress which has been achieved both with diagnosis and treatment. Preventative measures ought to be developed and realistically assessed before their introduction. Today it is indispensable to measure the impact of these measures, whether they have been previously or recently proposed by therapeutic trials. The current techniques proposed to prevent the appearance of nosocomial pneumonia are integrated in the usual conventional group of measures in the struggle against nosocomial infection which rests predominantly on standard approaches to hospital hygiene. These may be more specifically directed at good practical measures for the care of the ventilated patient. Regular toilet to the digestive and respiratory pathway, care of the ventilator material, absence of the changing of ventilation tubing during the stay. A certain number of measures are specifically suggested to prevent pneumonias: they have been imperfectly evaluated in clinical practice and remain controversial. Thus selective decontamination of the digestive system has not been dealt with her but also the sitting position, the utilisation of turning or oscillating beds, the continuous aspiration of oropharyngeal secretions or the use of Sucralfate as a means of prevention stress ulcers. Today, and until a complete evaluation of different techniques, the prevention of acquired pneumopathy during artificial ventilation rests above all on extremely simple measures; these cost little and are essentially meticulous care of the upper respiratory and digestive apparatus, to tracheal aspiration and physiotherapy which assure effective drainage and secretions, the use of the semi-sitting position, a well positioned gastric tube, in other words, basic care of the ventilated patient of a very good quality.

Beds↗
PubMed1994

Mortality attributable to nosocomial infections in the ICU.

Although a direct relationship between nosocomial infection and mortality in intensive care unit (ICU) patients has not always been demonstrated formally, it is possible to conclude that nosocomial infections increase the risk of death in critically ill patients. A more precise analysis indicates that: 1) this effect is highly probable for pneumonia, doubtful for bacteremia, and uncertain for urinary tract infection; 2) risk increases with duration of stay in the ICU; 3) bacterial etiology modifies the risk; and 4) this effect is stronger in less severely ill patients, probably because the severity of underlying disease remains the most significant factor.

Bacteremia↗
PubMed1994

Evaluation of human cytomegalovirus latency in alveolar macrophages.

Cytomegalovirus (CMV) pneumonia is a major cause of illness in immunocompromised patients. The sites of human CMV (HCMV) latency are still not clearly defined. The present study was therefore designed to investigate the hypothesis that alveolar macrophages could constitute such a site. DNA extracted from alveolar cells collected by bronchoalveolar lavage and blood mononuclear cells (BMC) from asymptomatic nonimmunocompromised CMV-seropositive and CMV-seronegative patients were investigated. Controls consisted of DNA from a CMV-infected MRC5 cell line, BMC and alveolar macrophages from patients with acute CMV infection. Polymerase chain reaction (PCR) was designed for detection of a 290-bp fragment of the promoter region of the major immediate early gene of HCMV conserved within the various HCMV strains and without homology with the human genome. The limit of detection of the method was evaluated to be one HCMV viral copy per 10(4) cells. HCMV DNA was detected in BMC or alveolar cells of all patients with acute CMV infection. In contrast, no HCMV DNA was detected in alveolar cells and BMC from nonimmunocompromised asymptomatic HCMV-seropositive patients. In conclusion, in the present experiment, no latent HCMV could be detected in alveolar cells collected in nonimmunocompromised asymptomatic CMV-seropositive patients.

Adult↗
PubMed1990

[Expanded trans-pedicular spongiosa grafting--dorsal approach to filling of the intervertebral spaces with cancellous bone].

Internal fixation of dorsolumbar spinal fractures can be accomplished by dorsal plating or internal fixator. So far, the technique of transpedicular grafting has been applied to fill the vertebral body with cancellous bone. In this paper, we present a new technique of extended transpedicular bone grafting to fill the intervertebral space also. By this means, the disadvantage of secondary loss of height after removal of the metal implants can be prevented.

Bone Plates↗
PubMed1989

Nonsuture microsurgical vessel anastomosis using an absorbable cuff.

The nonabsorbable cuff used for nonsuture anastomosis can cause residual vessel stenosis as well as regional wall rigidity. Resulting disturbances in laminar flow promote the development of irregularities in the intimal endothelial vessel lining distal to the anastomosis. Using absorbable cuffs, the degree of stenosis can be appreciably reduced, thereby diminishing thrombogenic flow turbulence. The absorbable cuff can thus facilitate clinical application of nonsuture microsurgical vessel anastomosis.

Anastomosis, Surgical↗
PubMed1984

The role of insulin, glucagon and growth hormone in the regulation of plasma glucose and free fatty acid levels in anorexia nervosa.

It is well established that glucagon plays an important role in the regulation of fuel supplies as its plasma level increases during the first days of a complete fast. However, it is not certain that glucagon is involved in the adaptation to chronic starvation. In the present study, this problem was investigated by the determination of the changes in the plasma glucagon level elicited by an i.v. glucose tolerance test followed by an i.v. arginine perfusion in 26 self starved patients suffering from anorexia nervosa (AN) and 14 control patients having only minor neurotic disorders. The basal plasma glucagon level tended to be higher in the AN patients than in the controls; but the difference was not statistically significant. Glucagon responses to glucose and arginine observed in the AN patients were not significantly different from those seen in the control patients. In the AN patients, the insulin response to both loads was reduced and the plasma GH level increased paradoxically after the glucose load, whereas it rose normally after the arginine load. It may be concluded that in chronic starvation by AN the regulation of fuel supplies depends mainly on decreased insulin and increased growth hormone secretion. The role of glucagon seems to be of minor importance in this condition.

Adolescent↗