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P Ruffieux

Publications and source records attributed to P Ruffieux.

13 recordsLinked to original sources
PubMed2000

Hydrogen atoms cause long-range electronic effects on graphite

We report on long-range electronic effects caused by hydrogen-carbon interaction at the graphite surface. Two types of defects could be distinguished with a combined mode of scanning tunneling microscopy and atomic force microscopy: chemisorption of hydrogen on the basal plane of graphite and atomic vacancy formation. Both types show a (sqrt[3]xsqrt[3])R30 degrees superlattice in the local density of states but have a different topographic structure. The range of modifications in the electronic structure, of fundamental importance for electronic devices based on carbon nanostructures, has been found to be of the order of 20-25 lattice constants.

Journal Article↗
PubMed2000

A new method for on-line measurement of the volumetric oxygen uptake rate in membrane aerated animal cell cultures.

Oxygen is a key substrate in animal cell metabolism and its consumption is thus a parameter of great interest for bioprocess monitoring and control. A system for measuring it based on an oxygen balance on the liquid phase was developed. The use of a gas-permeable membrane offered the possibility to provide the required quantity of oxygen into the culture, while avoiding problems of foaming or shear stress generally linked to sparging. This aeration system allowed moreover to keep a known and constant k(L)a value through cultures up to 400 h. Oxygen uptake rate (OUR) was measured on-line with a very good accuracy of +/-5%, and the specific OUR for a CHO cell line was determined during batch (growth phase) and continuous culture as, respectively, equal to 2. 85x10(-13) and 2.54x10(-13) mol O(2) cell(-1) h(-1). It was also shown that OUR continuous monitoring gives actually more information about the metabolic state of the culture than the cell concentration itself, especially during transition phases like the end of the growth phase in a batch culture.

Animals↗
PubMed2000

Takayasu arteritis and cutaneous necrotizing vasculitis.

Takayasu arteritis (TA) is an inflammatory arteriopathy involving predominantly the aorta and its main branches. The disease evolves in two phases: a first, nonspecific inflammatory stage and a late 'pulseless' stage, in which complications related to arterial stenosis and aneurysm formation predominate. In both phases, skin manifestations, such as inflammatory nodules, erythema-nodosum- and pyoderma-gangrenosum-like ulcers, have been described. We report 2 patients with TA, who had cutaneous necrotizing vasculitis as presenting manifestation of the disease. A review of the literature revealed 8 similar cases. TA does not only involve large arteries, but also small blood vessels. The observation that in TA the inflammatory process of the large arteries affects regions of the walls supplied by the vasa vasorum, the anatomy of which bears resemblance to the cutaneous vessel system, suggests that primary involvement of small vessels contributes to the development of the clinicopathological features of TA. Knowledge of the skin manifestations associated with TA remains important for its diagnosis and prompt instauration of life-saving treatment.

Adult↗
PubMed1998

[Epidermolysis bullosa acquisita and metastatic cancer of the uterine cervix].

INTRODUCTION: Epidermolysis bullosa acquisita may be associated to a systemic or malignant disease. Here, we report a case of epidermolysis bullosa acquisita associated with a carcinoma of the cervix. CASE REPORT: A 44-year-old woman presented inflammatory, bullous and erosive mucocutaneous lesions. Investigations lead to the diagnosis of epidermolysis bullosa acquisita and revealed pelvic metastases originating from a poorly differentiated carcinoma. The cutaneous lesions completely regressed after the treatment of the tumor but reappeared with tumoral relapse. DISCUSSION: This is the first report of an association of epidermolysis bullosa acquisita and carcinoma of the cervix. The clinical course of these two entities suggests that the EBA in this case may be paraneoplastic.

Adult↗
PubMed1997

Long-term assessment of chronic leg ulcer treatment by autologous skin grafts.

BACKGROUND: Chronic leg ulcers (CLU) are a common and major cause of morbidity. For this reason, we systematically perform autologous skin grafting. OBJECTIVE: Long-term evaluation of this treatment. PATIENTS AND METHODS: Among the 521 out-patients or those hospitalized for CLU between 1981 and 1993, we assessed 188 (118 women, 70 men, mean age 74 years, 144 grafts, 44 non-grafted). RESULTS: For the grafted CLU, there were 46 failures (17.5%), 152 (58%) healed in a mean time of 2.2 months and 64 relapsed (24.5%). For the non-grafted CLU, 3 did not heal (3%), 20 relapsed (22.5%) and 66 healed (74.5%) in a mean time of 4.7 months. All the patients who suffered from painful CLU mentioned a regression of pain after the graft. Finally, 87.5% of patients declared that they would accept a new graft. CONCLUSIONS: We did not note any real difference in closure and recurrence rates between grafted and non-grafted ulcers. This is most likely due to an important selection bias related to the methodology of our study. The grafted ulcers were more serious: they were larger (28.9 against 7.9 cm2) and older (11.1 against 5.6 months).

Adult↗
PubMed1997

Cellulitis after hip surgery: long-term follow-up of seven cases.

Cellulitis of the buttock after hip surgery is rarely reported, but raises concern about possible infection of the implant. In view of this we have investigated the frequency of previous hip surgery in patients with cellulitis of the hip and/or buttock and assessed for any predisposing factors. A review was made of the case notes of all patients admitted to our department with infectious cellulitis of the hip and/or buttock between 1981 and 1995. Seven of nine patients previously had had implantation of a hip prosthesis. The interval between skin infection and surgery was 7-9 weeks in two patients and 55-520 weeks in five. No infection of the implant was evident. The assumed portals of entry were gluteal fold intertrigo, tinea pedis, psoriatic plaque and a carbuncle of the buttock. The infection was successfully treated by intravenous antibiotics and, after a follow-up of a mean 64 months, no recurrence of cellulitis has been observed and only one aseptic loosening has occurred. Infectious cellulitis of the hip or buttock following hip surgery can occur secondary to impaired lymphatic drainage, a few weeks up to several years after surgery, without there being any infection of the orthopaedic implant.

Aged↗
PubMed1996

Livedo-like dermatitis (Nicolau's syndrome): a review of three cases.

We report 3 patients with typical features of livedo-like dermatitis. Emergency vasoactive therapy was administered to 2 of these patients, in whom the lesions healed completely. Although spontaneous resolution cannot be ruled out, we think that early recognition of this entity leading to rapid vasoactive treatment may limit the extent of thrombotic complications and the resulting tissue necrosis.

Aged↗
PubMed1994

Topical haemotherapy for leg ulcers.

Several growth factors, present in the plasma or delivered by blood cells, are involved in wound healing. We have treated 15 chronic atonic leg ulcers by topical application of autologous heparinized blood under a hydrocolloidal dressing. This 'topical haemotherapy' (THT) was applied every other day. After the first THT, 30% of the fibrinonecrotic material had already been removed. After a mean of 9 THT applications (range: 5-18), granulation tissue covered up to 75% of the surface of the ulcer (range: 30-100%) allowing autologous skin grafting. No local or systemic side-effects occurred during the treatment. THT is feasible and well tolerated; it is an easy and inexpensive treatment of chronic leg ulcers that rapidly induces granulation tissue. Growth factors and proteases produced by the blood cells could play a relevant role in this process.

Administration, Topical↗
PubMed1993

Superficial granulomatous pyoderma.

We report the case of a 66-year-old man presenting 2 chronic, slowly expanding skin lesions having clinical and histopathological characteristics of superficial granulomatous pyoderma. Sulfone treatment induced healing with scar formation.

Abscess↗