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Biomedical subjects

F Leonard

Publications and source records attributed to F Leonard.

At least 19 recordsLinked to original sources
PubMed2005

[The prospective multicenter study on standard photopatch tests by the French Society of Photodermatology from 1991-2001].

INTRODUCTION: To develop a standard panel of photopatch tests, the French Society of Photodermatology conducted a prospective study from 1991 to 2001 on the frequency of photoallergens encountered in France and on the relevance of the choice of the various photoallergens. PATIENTS AND METHODS: Thirteen photobiology centers participated in the study from 1991 to 1995, and ten centers from 1995 to 2001. A set of 3 samples of photopatch tests was applied on any patient suspected of photoallergy. On Day 2, two sets were irradiated with ultraviolet A (UVA) and total spectrum (DEM 0.75); with the third set being used as control. Readings were made on D3 and D4. RESULTS: Two thousand sixty-seven patients were tested. Eight hundred fifty-six, i.e., 41% exhibited one or several positive tests. In the majority of cases it was a photoallergy (39.7 to 60% of cases) and eczema (29.5 to 45.6%). Photoaggravation was infrequent (7.9 to 10.3%). Cases of phototoxicity were rare. Sesquiterpenic lactones constantly provoked photoallergy, with 12 cases in 10 years. Although phenothiazines were the most photosensitizing allergens up until 1995, they were then overridden by ketoprofen in 1996 with 107 cases of UVA photosensitive reactions (75 cases) and total spectrum (32 cases). These were followed closely by sun screens, benzophenone (notably Eusolex 4360 with 54 pertinent cases of photoallergy) and dibenzoylmethane (with 31 cases due to Eusolex 8020). UVB filters were all potentially photosensitizing but to a lesser degree from 1 to 5 cases). DISCUSSION: Our results differ from those of Anglo-Saxon teams in the appearance of a new photoallergen, ketoprofen, which provoked numerous photosensitivities in both UVA and UVB. This justifies the systematic addition of this substance in our prospective set. Photoallergy was relatively rare, with around 100 cases reported within 10 years. Total spectrum irradiation of the photopatch tests revealed photoallergies that would not have been found with UVA alone. CONCLUSION: Study of photopatch tests has permitted the uniformization of the methodology in France, an overview of the frequency of the photoallergens tested and the development of a new standard set.

France↗
PubMed2004

Photopatch testing: a consensus methodology for Europe.

A group of interested European Contact Dermatologists/Photobiologists met to produce a consensus statement on methodology, test materials and interpretation of photopatch testing. While it is recognized that a range of local variables operate throughout Europe, the underlying purpose of the work is to act as an essential preamble to a Pan European Photopatch Test Study focusing particularly on sunscreen chemicals.

Dermatitis, Photoallergic↗
PubMed2002

[Positive photobiological investigation in Jessner's lymphocytic infiltration of the skin].

BACKGROUND: Jessner's lymphocytic infiltration of the skin is a rare and benign disorder. Its clinical course is cyclic with remissions and exacerbations. In this disease, photosensitivity was previously noticed by authors and recently demonstrated. We report four new cases with positive photobiological investigation. CASE REPORTS: Four patients (2 males, 2 females), with a mean age 36 years were seen with erythematous papules or discoid plaques on face, arms and upper trunk. The onset of disease occurred after sun exposure in summer. Skin biopsies showed perivascular lymphocytic infiltration in the dermis. All patients relapsed cyclically with incomplete healing during winter. Photobiological investigation elicited skin lesions in a broad spectrum of UV: UVB (2 cases), UVA (1 case), UVA and UVB (1 case). In all patients treatment with oral antimalarials and external photoprotection was effective. DISCUSSION: Our data suggest that photosensitivity history in patients with Jessner's lymphocytic infiltration of the skin should be searched for, and confirmed by provocative phototesting. This relevant event could guide the therapeutic strategy because antimalarials were effective for the Jessner's lymphocytic infiltration cases with photosensitivity.

Adult↗
PubMed2001

Modulation of intestinal vitamin D receptor availability and calcium ATPase activity by essential fatty acids.

The physiological mechanisms by which essential fatty acids (EFAs) affect calcium (Ca(2+)) retention is not clear, but suggestions have included changes in membrane fluidity, receptor modulation and induction of second messengers. The vitamin D receptor (VDR) is essential for the functioning of 1,25(OH)(2)D(3)which increases Ca(2+)absorption. Activity of the intestinal basolateral membrane (BLM) Ca(2+)ATPase correlates with the degree of Ca(2+)absorption. Therefore, changes in ATPase activity and VDR availability due to EFAs may influence calcium retention. We have investigated the effect of long-term dietary supplementation with EFAs on Ca(2+)ATPase activity (measured colourimetrically) and VDR availability (measured with the ELISA technique) after the loss of oestrogen induced by ovariectomy (OVX) in female Sprague Dawley rats. Control animals underwent anaesthesia and a surgical procedure but the ovaries were left intact (sham). Ca(2+)ATPase activity was significantly lower in OVX animals than in the intact animals (P<0.05) and following supplementation with EFAs, was significantly higher than in sham controls (P<0.05). A higher number of VDR was measured after OVX and declined due to EFA supplementation; these differences in activity of the ATPase and number of receptors could be ascribed to membrane changes due to EFA supplementation, feedback control by serum calcium or the direct influence of the EFAs.

Animals↗
PubMed2000

Negative differential resistance in nanotube devices

Carbon nanotube junctions are predicted to exhibit negative differential resistance, with very high peak-to-valley current ratios even at room temperature. We treat both nanotube p-n junctions and undoped metal-nanotube-metal junctions, calculating quantum transport through the self-consistent potential within a tight-binding approximation. The undoped junctions in particular may be suitable for device integration.

Journal Article↗
PubMed2000

Role of fermi-level pinning in nanotube schottky diodes

At semiconductor-metal junctions, the Schottky barrier height is generally fixed by "Fermi-level pinning." We find that when a semiconducting carbon nanotube is end contacted to a metal (the optimal geometry for nanodevices), the behavior is radically different. Even when the Fermi level is fully "pinned" at the interface, the turn-on voltage is that expected for an unpinned junction. Thus the threshold may be adjusted for optimal device performance, which is not possible in planar contacts. Similar behavior is expected at heterojunctions between nanotubes and semiconductors.

Journal Article↗
PubMed2000

Direct cost of single dose methotrexate for unruptured ectopic pregnancy. Prospective comparison with laparoscopy.

OBJECTIVES: to compare the direct cost of single dose methotrexate (MTX) and laparoscopy in the treatment of unruptured ectopic pregnancy (unruptured EP). STUDY DESIGN: A prospective nonrandomized study. Thirty-two women received intramuscular MTX (1 mg/kg) on an out-patient basis when they fulfilled the following requirements: human chorionic gonadotropin (hCG) level <5000 IU/l, hematosalpinx diameter <3 cm and peritoneal fluid <100 cc. Follow-up consisted of clinical controls and hCG assays. Twenty-seven women eligible for MTX therapy according to the above conditions underwent laparoscopic salpingectomy because some of them refused the therapy while others had contraindications to MTX. We recorded all the medical expenses related to the out-patient and in-patient management for the two treatment options. The cost was calculated according to the French General Nomenclature of Professional Acts and expressed in Euros. RESULTS: MTX resulted in a significantly lower mean direct cost in comparison with surgery (E 1145 vs. 2442, P=0.006) that was mainly due to shortened hospital stay (1.1 vs. 2.8 days, P=0.007). Conversely MTX required a significantly higher number of medical acts during the follow-up. Costs for MTX therapy were closely related to the length of hospitalization and to the duration of the follow-up. CONCLUSION: Single dose MTX provides significant cost-savings when compared to laparoscopy. Savings reach a peak for small unruptured EP because hospitalization is not required and the length of follow-up reduced.

Abortifacient Agents, Nonsteroidal↗
PubMed2000

Perioperative morbidity of gynecological laparoscopy. A prospective monocenter observational study.

BACKGROUND: To study the morbidity rate of gynecological laparoscopy and to the most influential variables. METHODS: We conducted a prospective observational study from January 1st 1992 to December 31st 1998 in a single tertiary care center. It concerned patients who underwent gynecological laparoscopic surgery performed by seniors and residents. We have prospectively recorded patients characteristics, indications for laparoscopy, leading diagnosis, main operative procedures, post-operative course, surgical and anesthetic incidents and accidents. Complications were defined as any event that would modify the usual course of laparoscopy or of the post-operative period. RESULTS: One thousand and thirty-three laparoscopies were included. 80.1% of the procedures were major or advanced laparoscopies. The overall complication rate was 3%, with a laparotomy rate of 1.2%. About half of those complications (54.8%) occurred during the installation of laparoscopy. Veress needle and first trocar insertion accounted for 23.5% of those accidents (0.3% of the procedures) and suprapubic trocar insertion for 76.5%. Hemorrhages constituted almost all of the complications occurring during the operative stage (80%). The risk increased with the level of surgery and decreased with surgeon's experience. Prior abdominal surgery had no significant effect on the overall morbidity rate. Post-operative and anesthetic complications were rare. The overall complication rate as well as the laparotomy rate were stable all along the course of the study. CONCLUSIONS: Complication rate of gynecological laparoscopy is not negligible. Efforts should be made to lower the complications induced by the installation of laparoscopy, especially for secondary trocars.

Adolescent↗
PubMed2000

Inhibition of duodenal enterocyte Mg2+-ATPase by arachidonic acid is not mediated by an effect on protein kinase C.

Active absorption processes in the duodenal enterocyte are driven by various ATPases. It is known that the activity of Na+,K+-ATPase, Ca2+-ATPase and Mg2+-ATPase can be modulated by polyunsaturated fatty acids of the n-6 series, for example by linoleic and gamma-linolenic acids. These effects may be achieved by protein phosphorylation via protein kinase C. The present study was undertaken to determine the effect of arachidonic acid on Mg2+-ATPase (measured colorimetrically) activity in basolateral membranes prepared from rat duodenum. It shows, for the first time, significant dose-dependent inhibition of Mg2+-ATPase (26-62%) by arachidonic acid (10-50 microg/ml) which already takes place after one minute of exposure, indicating involvement of a rapid signal transduction mechanism. Addition of the protein kinase C inhibitors bisimidolylmaleimide (2.5 microM) and calphostin (0.5 microM) did not influence the action of arachidonic acid on Mg2+-ATPase; protein kinase C involvement in this process is thus not indicated.

Animals↗
PubMed1997

Aortic valve replacement in a United States Air Force pilot: case report and literature review.

We report the first case of a United States Air Force pilot returned to flying status after cardiac valve replacement. A 34-yr-old C-130 pilot underwent placement of an aortic valve homograft as a result of an episode of acute bacterial endocarditis on a bicuspid aortic valve. After a period of observation and a careful evaluation, he was returned to flying status in low-G aircraft. While cardiac valve replacement has traditionally been considered disqualifying for military aviation duties, aortic valve homografts have been associated with a lower morbidity and a significantly improved prognosis when compared to the other types of prosthetic heart valves. With careful evaluation and close follow-up, military aviators with aortic valve homografts can be considered for return to flying duties in low-G aircraft.

Acute Disease↗
PubMed1994

The United States Air Force crash ambulance--origins, current use, and suggested future directions.

The United States Air Force (USAF) maintains a crash ambulance, staffed by flight surgeons and aeromedical technicians, which is separate from the ambulance service maintained and staffed by base hospital or clinic personnel. A survey was performed to assess the current use and staffing of this ambulance. Results showed low use, and difficulties in training and maintaining experienced crews. A single integrated ambulance system is proposed to replace the current separate systems. Such a system could improve overall response capability, and more efficiently and effectively use available resources.

Accidents, Aviation↗
PubMed1993

Clinical tolerance of a combined monophasic contraceptive agent containing a low-dose of ethinyloestradiol and gestodene in adolescents.

The clinical effects and the contraceptive effectiveness of a monophasic preparation containing 30 micrograms ethinyloestradiol and 75 micrograms gestodene per tablet were assessed in a study of 115 healthy adolescents (mean age 18.5 +/- 2 years) covering a total of 712 menstrual cycles (mean of 8 cycles per patient). There was a number of cases of discontinuation of the study (70/115), mainly due to poor discipline in tablet intake in this particular age group. Only 20 cases discontinued the study for medical reasons. No pregnancies occurred, in spite of the fact that tablets were frequently forgotten (11% of cycles). Eighty-eight percent of cycles presented a normal bleeding pattern from the second month of treatment on. Spotting was sporadic (less than 8% from the 2nd cycle) and was mainly associated with tablet omission. Intermenstrual bleeding (breakthrough bleeding) occurred in 19% of the first menstrual cycles but only in 5% of the second and following cycles. Tenderness of the breast was the most frequent subjective complaint (3.4% of cycles), followed by urogenital problems, headaches and digestive disorders. However, all complaints remained sporadic (13.4% of cycles). The systolic blood pressure showed little variation, with only a slight increase from 123 to 125 mmHg after 6 months of treatment. Though not clinically important, an increase in diastolic blood pressure was observed (from 76 to 82 mmHg after 6 months). The patients showed a tendency to increase weight (from 54.4 to 56.7 kg after 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Seeking quality care for patients with pressure ulcers.

Improving quality care for patients with pressure ulcers resulted in a two-year intensive effort to educate staff, keep morale high, standardize care plans by stage of ulcer, and participate in a comparison study of two support surfaces (Thera-Pulse, Kinetic Concepts and Geo-Matt, SpanAmerica). When all pressure ulcers were considered, the analysis of covariance revealed no statistically significant difference in the healing of pressure ulcers with respect to type of support surface used (F[1, 78] = 0.35, p > .05). For patients with stage III and IV pressure ulcers, the proportion of patients improving more than 10cm2 was higher in the air-suspension group. There was relatively little difference in the Stage II ulcer patients.

Clinical Nursing Research↗