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Biomedical subjects

S Geiger

Publications and source records attributed to S Geiger.

At least 19 recordsLinked to original sources
PubMed2002

Impact of n-3 fatty acid supplemented parenteral nutrition on haemostasis patterns after major abdominal surgery.

In various diseases n-3 fatty acids exert anti-inflammatory properties. These effects seem to be related to the uptake and incorporation of eicosapentaenoic acid (EPA) into the cellular substrate pool after dietary intake of EPA, which is contained in fish oils (FO). In the state of inflammation EPA is released to compete with arachidonic acid (AA) for metabolism at the cyclo-oxygenase and the 5-lipoxygenase level. The metabolites of EPA have less inflammatory and chemotactic potency than the substances derived from AA. In addition to positive effects, early studies pointed towards prolonged bleeding times after dietary intake of n-3 fatty acids. This study was undertaken to address the issue of potential coagulation disturbances associated with postoperative parenteral FO administration. This was a prospective, randomised, double blinded clinical trial, carried out in two operative intensive care units (13 and 16 beds) in a university hospital. Forty-four patients undergoing elective major abdominal surgery participated in the trial. Patients were randomly assigned to receive total parenteral nutrition (TPN) supplemented with either soybean oil (SO, Lipovenoess 10% PLR; 1.0 g/kgBW per day; n = 20) for five days or with a combination of FO and SO (FO, Omegaven; 0.2 g/kgBW per day plus SO, Lipovenoes 10% PLR; 0.8 g/kgBW per day, n = 24), respectively. Blood samples were taken preoperatively (day -1), prior to (day 1) during (days 2-5) and after TPN (day 6). The coagulation parameters thromboplastin time (Quick), activated partial thromboplastin time (aPTT), fibrinogen and antithrombin III were measured. To differentially assess activation levels of extrinsic and intrinsic coagulation pathway, factors VIIa and XIIa were quantified. Moreover platelet function was determined by resonance thrombography. Baseline values of coagulation and platelet function were comparable in both groups, but coagulation activity dropped after surgery. Over the observation period of 6 days, however, physiological levels were regained. No clinically significant differences were observed between the SO- and SO + FO- group. These findings suggest that infusion of fish oil in doses up to 0.2 g/kgBW per day is safe regarding coagulation and platelet function.

Aged↗
PubMed2001

Monitoring of organ dysfunction in sepsis/systemic inflammatory response syndrome: novel strategies.

Sepsis and systemic inflammatory response syndrome-induced severe disruption of microcirculation and consecutive tissue hypoxia is considered a key factor in the development of organ dysfunction and multiple organ failure. The conventionally measured global variables such as lactate or macrohemodynamic parameters using a pulmonary artery catheter do not adequately mirror microcirculatory disturbances. Evaluation of the severity of microcirculatory distress and the effectiveness of resuscitation strategies requires new clinical technologies aimed at the microcirculation. It is anticipated that novel techniques such as optical spectroscopy and intelligent biosensors will play a major role in the development of new monitoring systems. In general, the current monitoring of organ dysfunction is characterized by a trend from invasive to noninvasive and "safe" techniques, which provide bedside or even on-line monitoring and allow a more precise and earlier detection of organ dysfunction. Techniques for the assessment of regional perfusion and microcirculatory bioenergetics to direct therapeutic procedures are expected to refine and optimize clinical treatment of critically ill patients in the future. This article addresses the question of which variables should be monitored, what is feasible, and what is valid for therapeutic consequences. Recent developments in monitoring of macro- and microcirculation and organ-specific dysfunction, e.g., lung, kidney, are described with respect to their advantages and limitations, and future directions are outlined.

Humans↗
PubMed1999

Controlled release of vancomycin from poloxamer 407 gels.

The purpose of this study was to investigate Poloxamer 407 25% (w/w) formulations aimed at prolonging the residence time of vancomycin, a time-dependent antibiotic, in a body site with a high infectious risk. Reversible thermal gelation of the formulations permitted their local injection in liquid form and in situ gelation as they warmed to body temperature. Neither the rheological properties of the Poloxamer matrices nor the antibacterial activity of vancomycin was altered by their combination. In vitro, the dispersed form exhibited prolonged release, with a lower diffusion coefficient of vancomycin compared to the solubilized form (4.7x10(-8) vs 2. 1x10(-7) cm(2) s(-1)131 mg l(-1) for the solubilized form), followed by lower but effective antibacterial levels for at least 8 days. Controlled-release profiles, good preservation of vancomycin activity, good tolerability in rats, and ease of administration suggest that Poloxamer 407 may be useful as a vancomycin delivery vehicle for local prophylaxis of infections, especially in prosthetic surgery.

Animals↗
PubMed1999

Percutaneous absorption of sunscreens from liquid crystalline phases.

The purpose of the present study was to investigate the effects of two nonionic surfactants with liquid crystalline structures on the cutaneous availability of two sunscreens. Three liquid crystalline structures were investigated: lamellar, hexagonal and cubic. The diffusion of sunscreens within the liquid crystals was determined by measuring transport kinetics into an unloaded surfactant medium from a similar system loaded with the sunscreens. The diffusion coefficients were the greatest in the cubic systems for benzophenone-4 (a hydrosoluble sunscreen) and in lamellar systems for octyl methoxycinnamate (a liposoluble sunscreen). So the diffusion in this surfactant systems was strongly dependent on the structure of the liquid crystal and on the physicochemical properties of the solute. The transcutaneous fluxes were determined using a Franz-type diffusion cell. The liquid crystalline vehicles modified the transcutaneous fluxes of benzophenone-4 but did not change those of octyl methoxycinnamate. The solute diffusion within the vehicle was not the rate-determining step for transcutaneous permeation for either sunscreen. The diffusion of benzopenone-4 within the stratum corneum and that of octyl methoxycinnamate within the dermis could be the rate-determining steps for their transcutaneous permeation. These two steps could be affected differently by nonionic surfactant vehicles.

Animals↗
PubMed1999

Surface roughness evaluation of resin modified glass-ionomers polished utilizing poly(acrylic acid) gel.

The differences in polishability of modified and conventional glass-ionomers were studied following different polishing procedures. Specimens of conventional glass-ionomer (Fuji II(R)), resin modified glass-ionomer (Vitremer(R)) and compomer (Dyract(R)) were prepared and polished using either Soflex(R) or Enhance(R) discs with either aluminum oxide or poly(acrylic acid) gel as polishing agents. Surface roughness of the specimens was evaluated by profilometric measurements and electron microscopic examination. It was shown that Soflex(R) discs manifest superior polishing effect on glass-ionomers and resin modified glass-ionomers compared to the Enhance(R) system, although no significant differences were found for the compomer specimens. Addition of poly(acrylic acid) gel as a polishing agent reduced surface roughness of conventional glass-ionomer and resin modified glass-ionomer specimens and did not significantly affect the compomer specimens.

Acrylic Resins↗
PubMed1998

Kinetics of swelling-breakdown of a W/O/W multiple emulsion: possible mechanisms for the lipophilic surfactant effect.

The properties and behavior of a W/O/W multiple emulsion formulation were analyzed during a swelling-breakdown process. Various experimental analyses, such as granulometry, rheology and conductimetry were performed, as well as a micropipette aspiration method. The predominant role of the lipophilic surfactant during the swelling phase confirmed. Two different mechanism can be proposed. Both imply the migration of the lipophilic surfactant from one interface to another and probably take place successively. The lipophilic surfactant could diffuse from the first to the second interface, thus rigidifying the membrane, or from the oily phase to the first interface, resulting in delayed coalescence of the aqueous droplets during swelling.

Emulsions↗
PubMed1995

Changes in microrheology of acute promyelocytic leukemia cells during all-trans retinoic acid (ATRA) differentiation therapy: a mechanism for ATRA-induced hyperleukocytosis?

According to French and European experience, hyperleukocytosis occurs during ATRA differentiation therapy in about 70% of de novo and 25% of relapsed APL cases. The most frequently suggested cause for this side-effect is an ATRA-induced proliferation of APL cells. However, no definite explanation for such a proliferative effect has been clearly established. Another mechanism directly related to the differentiation of marrow leukemic cells could be a change in their microrheology, allowing their release from the bone marrow and their transfer toward peripheral blood (PB) and tissues. Using a single cell aspiration assay into a glass restrictive channel, we measured APL cell viscosity values in five de novo APL patients. A deformability index (DI) was defined as the ratio of mean normal neutrophil viscosity x 100/mean APL cell viscosity. Results were the following: (1) at diagnosis, two patients had high marrow DI (96 and 250%) and three patients had low marrow DI (16, 17, and 40%); (2) when PB and marrow APL cells were simultaneously tested, PB APL cells display higher DI than marrow APL-cells; (3) the two patients with high initial marrow DI experienced an ATRA-induced hyperleukocytosis after only 1 day of treatment; (4) in the three patients with low initial marrow DI, the DI was increasing during ATRA therapy and hyperleukocytosis seemed to occur when a large amount of maturing APL cells reached a viscosity value similar to that of mature neutrophils. These results suggest that an asynchronism between rheological and morphological maturation in each APL cell might explain the occurrence of hyperleukocytosis in some patients during ATRA differentiation therapy.

Adult↗
PubMed1994

Surface texture evaluation of glass ionomer restorative materials polished utilizing poly(acrylic acid) gel.

This study evaluated the surface texture of three different glass ionomer restorative materials and a composite resin, polished by a new method using poly(acrylic acid) gel. Conventional polishing methods and finishing agents were compared to the proposed new procedure. Evaluations were carried out employing three techniques: profilometry, scanning electron microscopy and microhardness testing. The use of a poly(acrylic acid) gel with polishing discs gave significantly better results, and is therefore recommended for clinical applications.

Acrylic Resins↗
PubMed1994

[Microrheology of marrow promyelocytes from patients suffering from acute myeloblastic leukemia type 3].

Viscosity values of marrow cells from patients suffering from acute promyelocytic leukemia (acute myeloid leukemia of type 3) have been determined before and during a treatment with all-trans retinoïc acid (active metabolite of the vitamin A, inducing cell differentiation and maturation). Evaluated from aspiration tests into a glass micropipette, the marrow cell viscosity has been compared to that of normal neutrophils. Results seem to point out that the induced hyperleucocytosis is favoured by both a low standard deviation of pathological cell viscosity and a cell viscosity value close to that of normal neutrophils. The systematic study of cell viscosity could therefore help the clinicians to individualize the treatment.

Granulocytes↗
PubMed1993

[The prognostic importance of calcitonin screening in familial medullary thyroid carcinoma].

In 34 of 139 patients (63 men, 76 women, mean age 41.2 +/- 15.6 years) with medullary thyroid carcinoma (MTC) the disease was of the familial variety. 13 of the 34 cases were discovered in the preclinical stage by screening (calcitonin stimulation with pentagastrin). This group was on average younger (16.8 +/- 10.7 years) than the 21 clinically manifest patients with MTC (28.0 +/- 11.9 years) or the 105 patients with sporadic MTC (45.7 +/- 13.6 years). The patients diagnosed through the screening programme had a more favourable tumour stage (12 in stage I or II) and were thus more likely to be cured. Their survival rate was higher (100% at both 5 and 10 years) than the survival rate of the patients with clinically manifest tumour (94 and 87%, respectively). But the group with manifest familial MTC did not differ from those with sporadic occurrence as regards the tumour stage (predominantly advanced stages), limited chance of cure and survival rate (5 years: 94%, 10 years: 81%). These data show that screening of family members decisively improves the prognosis of MTC of the familial variety.

Adult↗
PubMed1991

Effect of water spray on lining materials and their adhesion to composite and dentin cavity walls.

The effect of an air-water spray on the adhesion of lining materials to both overlying composite restorations and cavity walls was evaluated. An in vitro study was performed on extracted molar teeth: Two resinous light-cured liners and one calcium hydroxide, chemically activated liner were compared. Teeth were restored with composite materials and subjected to cyclic thermal changes so that microleakage could be evaluated. Results indicated that adaptation between the restorative material and the liner was effective, regardless of whether the oxygen-inhibited layer was removed by being rinsed. A definite gap was detected between the liners tested and the dentin cavity walls.

Acrylic Resins↗
PubMed1988

The effects of partial demineralization and fibronectin on migration and growth of gingival epithelial cells on cementum in vitro.

The capacity of mineralized cementum to support epithelial cell migration and growth and the effect that fibronectin and partial demineralization of cementum have on these processes were assessed in vitro. Dog gingival explants, 1 X 2 mm, were cultured on the cementum surfaces of pig root pieces in a defined medium consisting of DMEM and F12 (1V/1V), transferrin, insulin, epidermal growth factor, cortisone, selenium, and high-density lipoprotein. Sixty root pieces were divided into four equal groups according to the treatment: (1) untreated mineralized cementum; (2) treated with 5 micrograms of fibronectin; (3) partially demineralized in 18% EDTA for 30 min; and (4) both partially demineralized and fibronectin-treated as above. Epithelial cell migration and growth on each of the four differently treated cementum surfaces were assessed histomorphometrically by means of scanning electron microscopy. The defined culture medium supported the selective migration and growth of epithelial cells from the gingival explants onto the mineralized cementum. This was confirmed by the positive immunostaining of these cells with antikeratin antibodies. Partial demineralization of cementum inhibited epithelial migration and growth by 83% and 91%, respectively. Fibronectin treatment did not affect epithelial cell migration and growth on mineralized cementum, but it decreased the degree of epithelial cell migration and growth inhibition on partially demineralized cementum to 57% and 43%, respectively. The results indicate that: (i) mineralized cementum may consist of components that are recognized by gingival epithelial cells and support their migration and growth in vitro; (ii) these components can be removed by demineralization; and (iii) fibronectin partially restores epithelial cell migration and growth on partial demineralized cementum in vitro.

Animals↗
PubMed1987

Cytokeratin polypeptides expression in different epithelial elements of human salivary glands.

Immunofluorescent labeling of human salivary glands was carried out with a battery of monoclonal antibodies reactive with specific cytokeratin polypeptides. All the epithelial elements of the glands were positively labelled by a broad-spectrum cytokeratin antibody (KG 8.13) and by antibody Ks 18.18, which reacts with cytokeratin No. 18 exclusively. Labelling of frozen sections with antibody KM 4.62, which is reactive with the 40 Kd (No. 19) cytokeratin, was confined to the ductal system and apparently absent from the acini. Antibody KA-1, reactive with polypeptides 4, 5 and 6 stained both the myoepithelial cells and the basal cells of the large ducts. Antibody KS 8.58, however, reacted with the basal cells exclusively. It is thus proposed that the combined use of the various monoclonal antibodies may provide a most useful probe in studies on epithelial cell diversity in normal salivary glands as well as in pathological disorders of that gland.

Child↗
PubMed1985

Embryonal rhabdomyosarcoma: immunohistochemical characterization.

A 15-year-old boy was referred to the ear, nose, and throat clinic because of a swelling in the upper premolar region. The initial diagnosis of a poorly differentiated soft-tissue sarcoma was made. Further immunohistochemical studies established a definitive diagnosis of embryonal rhabdomyosarcoma. The tumor cells coexpressed both desmin, the component of muscle type intermediate filaments, and vimentin, which is typically found in mesenchymal tissues. Such coexpression is found in the early stages of myogenic differentiation. Another cytoskeletal protein, actin, was also found in relatively high concentrations. These results suggested the possible use of antibodies to these cytoskeletal proteins as histogenetic markers for the diagnosis of poorly differentiated rhabdomyosarcoma.

Actins↗