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Biomedical subjects

F Walter

Publications and source records attributed to F Walter.

At least 19 recordsLinked to original sources
PubMed2004

Allergen-loaded biodegradable poly(D,L-lactic-co-glycolic) acid nanoparticles down-regulate an ongoing Th2 response in the BALB/c mouse model.

BACKGROUND AND OBJECTIVE: Biocompatible and biodegradable microparticles have gained interest as antigen delivery systems during the recent years. We investigated whether biodegradable poly(d,l-lactic-co-glycolic) acid (PLGA) nanospheres could be used as allergen vehicles for few-shot therapy of type I allergy. METHODS: The major birch pollen allergen Bet v 1 was encapsulated in PLGA nanospheres (PLGA-Bet v 1). We examined the antigenicity and the immune response to PLGA-Bet v 1 in a BALB/c mouse model. RESULTS: The antigenicity of Bet v 1 was largely unaffected by PLGA entrapment. When BALB/c mice were immunized subcutaneously with PLGA-Bet v 1, they formed allergen-specific IgG antibodies, but did not develop hypersensitivity to Bet v 1, as shown by type I skin tests. To evaluate their therapeutic potential, PLGA-Bet v 1 with or without Al(OH)3 or non-entrapped Bet v 1 with Al(OH)3 were used for single-shot treatment of sensitized mice. Both groups treated with PLGA-Bet v 1 developed high levels of Bet v 1-specific IgG2a antibodies (P<0.01), whereas IgG1 levels decreased significantly (P<0.01). Moreover, T cells from mice treated with PLGA-Bet v 1 showed IFN-gamma and IL-10 production. The synthesis of these cytokines was enhanced in the groups where Al(OH)3 had been added to the vaccine formulation. CONCLUSION: Allergen-loaded PLGA nanoparticles modulate an ongoing Th2 response in the BALB/c mouse model, as demonstrated by down-regulation of IgG1 and production of IFN-gamma and IL-10. Our data strongly suggest that PLGA nanospheres can advantageously be used for formulations of allergen extracts or allergen derivatives for the few-shot treatment of type I allergy.

Allergens↗
PubMed2003

[Postoperative pain therapy with tilidin and tilidin retard as an oral patient-controlled analgesia after uncomplicated myocardial revascularization].

OBJECTIVE: The purpose of this study was to evaluate whether or not the combination of tilidin and tilidin retard as oral patient-controlled analgesia provide a suitable pain management in patients after uncomplicated myocardial revascularization. METHODS: We conducted a randomised phase IV study to evaluate the effectiveness of postoperative analgesia with tilidin and tilidin retard. Patients with a baseline tilidin retard and tilidin liquid demand medication (group B, 42 patients) were compared with a base line paracetamol and tramadol-HCl liquid demand medication (group A, 44 patients). All patients received the first dose of study medication at the second postoperative day after evaluation of the individual pain score using NRS (numeric rating scale). RESULTS: Pain relief in group B was significantly better only at the second postoperative day (NRS 1,8 compared to 3,3 in group A), associated with tolerable side effects and comfortable handling. CONCLUSION: The combination of sustained release with immediate release drugs as a patient controlled analgesia provides suitable and comfortable analgesia after myocardial bypass surgery.

Administration, Oral↗
PubMed2003

Breast cell proliferation in postmenopausal women during HRT evaluated through fine needle aspiration cytology.

The basis of breast cancer risk associated with hormonal therapies may lie in the regulation of cell proliferation. In a prospective, double-blind, randomized study postmenopausal women were given continuous combined hormone replacement therapy (HRT) either as estradiol valerate 2 mg/dienogest 2 mg, (E2V/DNG) or estradiol 2 mg/noretisterone acetate 1 mg (E2/NETA) for 6 months. Fine needle aspiration (FNA) biopsies were used for immunocytochemical analysis of breast cell proliferation before and during treatment. From 45 women completing the study 135 biopsies were obtained. In the total material there was a more than 4-fold increase in proliferation between baseline and 3 months (p < 0.001). The mean percentage of MIB-1 positive breast cells increased from 2.2 to 9.1%. In some individual women values were as high as 25%. No further increase was recorded at 6 months. While numerical values were somewhat lower in the E2V/DNG group, there were no significant differences between treatments. There was a positive correlation between breast cell proliferation (MIB-1%) and circulating levels of both estradiol (r(s) = 0.54, p < 0.01) and estrone (r(s) = 0.53, p < 0.01) after 3 and 6 months of treatment. No correlations with other endogenous hormones, proteins or with the two exogenous progestogens dienogest and norethisterone were observed. Increased breast cell proliferation should probably be regarded as an unwanted side-effect during HRT. Means to identify those women with the most pronounced proliferative response should be developed. The FNA biopsy technique may be a useful tool to monitor and evaluate the proliferative response to HRT in the normal breasts of postmenopausal women.

Biopsy, Needle↗
PubMed2002

Indirect lymph node lymphangiography using an iodine-based contrast medium and projection radiography following submucosal injection in a rabbit model.

BACKGROUND: This study investigated the possibility of local lymph node detection and lymphatic mapping following submucosal injection of an iodine-based contrast medium. METHODS AND MATERIALS: We established a contrast medium (oil/water emulsion on iodine basis) with a particle size of mainly 1.7+/-0.1 micro m. Ten rabbits received rectal submucosal injections of the contrast medium and underwent repeated projection radiography. RESULTS: Passage of the contrast medium into lymphatic vessels and storage in lymph nodes was seen in all ten animals. The best contrast was achieved within 24 and 48 h after injection. Lymph nodes were still seen in eight cases with the final radiograph on day 14. There were no clinical side effects observed. Injection sites showed mild signs of inflammation in histological examinations. Pathological signs were not detectable in lymph nodes containing the contrast media. CONCLUSIONS: This method appears useful when investigating local lymph nodes following submucosal injection due to its passage into lymphatic vessels and storage in lymph nodes.

Administration, Rectal↗
PubMed2002

[Lipomatous tumors of soft tissues in the extremities and the waist in adults].

Lipomatous tumors of the upper and lower extremities in adults are frequent and lipoma is the most common soft tissue tumor. Most have a typical appearance at imaging but presentation and management may vary based on the exact histological subtype. The purpose of this paper is to review the main clinical, radiological and histological features of the different benign and malignant lipomatous tumors.

Abdomen↗
PubMed2001

Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre.

The nuclei of most galaxies are now believed to harbour supermassive black holes. The motions of stars in the central few light years of our Milky Way Galaxy indicate the presence of a dark object with a mass of about 2.6 x 106 solar masses (refs 2, 3). This object is spatially coincident with the compact radio source Sagittarius A* (Sgr A*) at the dynamical centre of the Galaxy, and the radio emission is thought to be powered by the gravitational potential energy released by matter as it accretes onto a supermassive black hole. Sgr A* is, however, much fainter than expected at all wavelengths, especially in X-rays, which has cast some doubt on this model. The first strong evidence for X-ray emission was found only recently. Here we report the discovery of rapid X-ray flaring from the direction of Sgr A*, which, together with the previously reported steady X-ray emission, provides compelling evidence that the emission is coming from the accretion of gas onto a supermassive black hole at the Galactic Centre.

Journal Article↗
PubMed2001

Structural evaluation of articular cartilage: potential contribution of magnetic resonance techniques used in clinical practice.

OBJECTIVE: To determine whether routine magnetic resonance imaging (MRI) techniques can detect age-related structural modifications of bovine articular cartilage. METHODS: The cartilage of 3-month-old, 3-year-old, and 13-year-old animals was studied. T1- and T2-weighted MR sequences were performed using a 1.5T clinical imager and a 3-inch surface coil. Histologic slices (5 microm) of cartilage specimens were stained with picrosirius red (for collagen) and toluidine blue (for glycosaminoglycans [GAGs]). A polarized light study was performed to determine the collagen network organization. Except for the 13-year-old animal cartilage, the biochemical content was studied on slices cut parallel to the surface to determine GAG and hydroxyproline (collagen) content. Cartilage profiles were performed to determine the MR pixel intensity and the histologic color intensity. RESULTS: On T1-weighted images, the cartilage was homogeneous, with pixel intensity profiles presenting low variations. On T2-weighted images, the cartilage was laminar in the 3-month-old animals and became homogeneous thereafter. The pixel intensity varied through the cartilage depth with a profile that depended on the age of the animal. The collagen and GAG staining showed abrupt transitions in the 3-month-old animal, while in older animals the cartilage became more homogeneous with a mild gradient of matrix constituents with depth. These results were confirmed by findings of a biochemical study. In addition to these matrix content variations, the bovine cartilage presented modifications of its collagen network organization with aging. CONCLUSION: The MR T2-weighted sequences depicted signal variations with age in bovine cartilage concomitant with modifications in its structure. If confirmed in clinics, these observations will reinforce the place of MRI in characterizing cartilage with aging and pathologic processes.

Aging↗
PubMed2001

MR imaging evaluation of suprascapular nerve entrapment.

The aim of this study was to assess the significance of muscular edema, atrophy, and fatty changes in the diagnosis of suprascapular nerve entrapment (SSNE), and to confirm muscular edema as the most significant sign of neuropathy. A retrospective study of 18 patients with suprascapular nerve entrapment was performed. All patients underwent electromyographic studies and MR imaging with a 1.5-T Echo Speed system (General Electric, Milwaukee, Wis.). The diagnosis of muscle edema was reached when muscles presented a high signal on T2-weighted fast spin-echo (SE) fat-suppressed images. Muscular trophicity and fatty changes were analyzed on a sagittal oblique cut using SE T1-weighted images. Intra- and inter-observer reproducibility using kappa test, sensitivity, and specificity were analyzed, together with negative and positive predictive value of each criterion. The topographic diagnosis was correct as edema affected the infraspinatus muscle alone when the suprascapular nerve was entrapped at the spinoglenoid notch. Both the supraspinatus and infraspinatus muscles were affected when nerve was compressed at the suprascapular notch. Sensitivity and specificity of muscular edema were, respectively, 94.5 and 100%. Muscular atrophy sensitivity and specificity were 81 and 80%, respectively. Fatty changes sensitivity and specificity were 25 and 96%, respectively. Muscular edema seems to be a more sensitive sign of SSNE than muscle atrophy and fatty changes when compared with EMG results. Magnetic resonance imaging can reach a positive, topographic, and etiologic diagnosis of SSNE.

Adolescent↗
PubMed2001

General practitioners' and patients' models of obesity: whose problem is it?

Primary care literature emphasises the importance of agreement and shared models in the consultation. This study compared general practitioners' (GPs') and patients' models of obesity. Questionnaires concerning beliefs about the causes, consequences and solutions to obesity were completed by 89 general practitioners (GPs) and 599 patients from practices across UK. In terms of causes, the results showed that the patients were more likely to attribute obesity to a gland/hormone problem, slow metabolism and stress than the GPs, whereas the GPs were more likely to blame eating too much. In terms of consequences, the patients rated difficulty getting to work more highly whereas the GPs regarded diabetes as more important. For the solutions to obesity, the two groups reported similar beliefs for a range of methods, but whereas the patients rated the GP and a counsellor as more helpful, the GPs rated the obese person themselves more highly. It is argued that patients show a self serving model of obesity by blaming internal uncontrollable factors for causing obesity yet expecting external factors to solve it. In contrast, GPs show a victim blaming model by attributing both cause and the solution to internal controllable factors. Such differing models have implications regarding the form of intervention likely to be used in primary care and indicate that whereas patients would prefer a more professional based approach, GPs would prefer a more patient-led one. Further, the results suggest that even if an intervention could be negotiated, success rates would be low as either the patient or the GP would be acting in contradiction to their beliefs about the nature of obesity.

Adult↗
PubMed2001

Crotalid envenomation: the southern Arizona experience.

OBJECTIVE: To review a regional experience with the treatment of snakebites. SETTING: Five major southern Arizona hospitals, including two Level I trauma centers. DESIGN: A review of all snakebite admissions over a five-year period was performed. RESULTS: During the period reviewed, 164 patients were admitted for snakebites. Rattlesnakes were responsible for 98 percent of identified envenomations. Thirty-six percent of the patients were transported by air to the admitting facility. Eighty percent of patients were admitted to the intensive care unit for an average of 1.6 days. Total hospital stays averaged 2.8 days. Ninety percent of patients received antivenin, usually only on the day of admission. Of those receiving antivenin, 20 percent had an anaphylactoid reaction, and 1 percent required readmission for serum sickness. Laboratory evaluation indicated abnormalities in platelet count, coagulation parameters, and fibrinogen levels, but these rarely required treatment. Thirteen percent of patients underwent surgical intervention, including a 4 percent fasciotomy rate, and a single amputation. CONCLUSION: The use of field treatment, including "cut and suck," tourniquets, and cryotherapy, increased the likelihood of surgery. The authors concluded that the intensive care unit and helicopter transport system were overused. They recommend that established objective envenomation severity scores be used to dictate patient treatment, specifically the use of antivenin.

Adolescent↗
PubMed2001

[Value of volume rendering in musculo-skeletal disorders].

Three dimensional imaging is increasingly important for evaluation of anatomic relationships and extent of disease, for treatment planning and for follow-up evaluation. The volume rendering technique allows creation of accurate 3D images that can be used for several clinical applications especially in musculo-skeletal disorders such as evaluation of tumors or fractures. This article describes the methods used for volume rendering technique and focuses on the specific aspects of volume rendering applied to musculo-skeletal applications.

Humans↗
PubMed2001

[Radiography of the upper limb revisited: the shoulder and the wrist].

CT scan and MR imaging are the most efficient techniques to evaluate the upper limb, however, standard radiography remains a valuable method to explore this anatomical region. In most situations, it is sufficient to allow a precise diagnosis and determine therapeutic protocols. However, this method can present a real diagnostic value only when it is guided by medical history and clinical data. The purpose of this work is to propose a practical approach for radiographic evaluation of the shoulder and the wrist, suited to the main clinical situations. CT-scan and MR imaging correlations will help to understand radiographic findings.

Humans↗
PubMed2001

[Value of arteriography scanning in lower limb artery evaluation: a preliminary study].

PURPOSE: The purpose of this study was to assess the feasability of CT Angiography (CTA) with a single row of detectors and to compare it to digital subtraction angiography (DSA) in the evaluation of lower limb peripheral arterial disease. MATERIAL: and methods. A total of 22 patients underwent 24 lower limb Helical CTA using a Somatom Plus 4A (Siemens) and 24 DSA using an Angiostar unit (Siemens). CT angiography was performed in one acquisition (collimation 3mm/ couch motion 9mm/ interval 2mm) with tube rotation time of 0.75 sec from the aortic bifurcation to the calf. DSA was performed after catheterization of a common femoral artery using the Seldinger technique. Arteries were classified in four categories (normal or stenosis<50%, stenosis>50%, occlusion, aneurysm). VRT images and axial source images were assessed by two independent radiologists whereas digital angiographies were read by a vascular radiologist. RESULTS: Global interobserver agreement was good (Kappa=0.71). The degree of agreement between CTA and DSA ranged from low to excellent (0.25 to 0.97) depending on the artery. CONCLUSION: Lower limb CT angiography is a promising non invasive technique. VRT allows quick evaluation. However, is not accurate enough to replace digital angiography.

Adult↗
PubMed2001

[Role of multiarray scanner in the choice of therapeutic strategy in kidney cancer. Report of a case of kidney tumor with double thrombus in inferior vena cava].

Renal cancer with caval thrombus is a disease which requires precise preoperative assessment, in order to adapt the surgical technique to the stage and extent of the disease. Recent developments in CT imaging, spiral acquisition and, more recently, the multiarray technique, allow a high quality evaluation. In the light of a case of right renal tumour with bifocal caval extension, the authors discuss the valuable contribution of this imaging modality in the staging assessment and evaluation of arterial (single or multiple artery, anatomical situation in relation to the left renal vein, presence of early bifurcations, etc.), and venous structures (renal vein, genital vein, extension of the thrombus, lumbar vein and hepatic vein). Improvements in CT imaging constitute a major progress in the staging of renal cancers with caval thrombus and make a considerable contribution to the choice of treatment strategy.

Aged↗
PubMed2000

Imaging of the painful lower limb stump.

Several postoperative complications associated with pain may develop in the stump of an amputated lower limb. Clinical findings are often nonspecific; however, radiologic evaluation, especially with magnetic resonance (MR) imaging, is useful in the early diagnosis of these complications, thereby helping minimize physical disability with its psychologic and socioeconomic implications. Conventional radiography can demonstrate evidence of osseous origins of pain (eg, aggressive bone edge, heterotopic ossification, osteomyelitis) and should be the first imaging study performed after clinical examination. Videofluoroscopy can help evaluate improper prosthetic fit by demonstrating abnormal residual limb motion, piston action, rolling of soft tissues, and abnormal angle between the limb axis and the prosthesis during gait. Ultrasonography can demonstrate inflammatory changes in the stump as well as soft-tissue fluid collections. However, MR imaging is the modality of choice when clinical and other imaging findings are indeterminate. Because of its high spatial and contrast resolution, MR imaging can demonstrate subtle inflammatory changes, fluid collections, cancers, neuromas, and subtle traumatic bone lesions. Knowledge of various surgical and rehabilitation techniques is required for accurate diagnosis of complications associated with stump pain. Correct diagnosis allows choice of the most appropriate therapy, which may involve treating the stump, remodeling the prosthesis, or both.

Amputation Stumps↗
PubMed2000

An aortocaval fistula diagnosed with 1.5-T magnetic resonance angiography.

We report a case of aortocaval fistula demonstrated with gadolinium-enhanced magnetic resonance (MR) angiography. Specific radiographic features of this rare complication, such as early and intense enhancement of the inferior vena cava, are underlined with MR imaging. The exact location of the fistula can also be assessed with this noninvasive imaging technique. Moreover, the absence of iodinated contrast media makes it particularly suited for stable patients with renal insufficiency. A complete preoperative assessment of abdominal aortic aneurysm can be performed with MR imaging.

Aged↗
PubMed2000

[Multislice CT: principles and new CT-scan applications].

The introduction of new array detector technology for multislice CT improves CT-scan capabilities. Compared to single-slice helical CT, this technique offers three significant advantages: the pitch can be increased by a factor of 4, resulting in shorter acquisition times and contrast media saving, the temporal and spatial resolution are improved and the slice thickness can be freely and retrospectively selected. This technique promises to revolutionize radiological practice, just as spiral systems did a decade ago. Multislice CT is particularly suitable for exploring the chest, the heart and the vessels. It is also specially useful for musculo-skeletal explorations and trauma patients.

Animals↗