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Biomedical subjects

M Walter

Publications and source records attributed to M Walter.

At least 37 records · Page 2Linked to original sources
PubMed2002

Esophageal necrosis and perforation of the left main bronchus following photodynamic therapy of esophageal carcinoma.

Photodynamic therapy is an effective palliative treatment of esophageal cancer. Minor complications associated with this therapy include pleural effusions, fever or esophageal strictures. In addition to this major complications such as respiratory-esophageal fistula and bronchus perforation have been described. We report here our experience with a patient who developed a complete esophageal necrosis and perforation of the left main bronchus following photodynamic therapy. The surgical and intensive care management of the patient is described and the literature discussed.

Bronchial Diseases↗
PubMed2002

[Aortic reconstruction and resection of malignant tumors--one- or two-stage procedure?].

Surgical tactics in case of aortic aneurysms and simultaneously performed cancer resections are not uniform and still remain a matter of debate. From Jan. 1, 1995 - Oct. 31, 2001 we operated on 37 patients suffering from aortic aneurysms (34 infrarenal, 2 combined thoraco- abdominal, 1 thoracic aneurysm) and cancer (11 esophageal, 6 gastric carcinomas, 3 small-bowel tumors, 5 large-bowel, and 12 renal carcino-mas). None of the above mentioned patients presented with any graft infection, or other severe p. op. complications. According to these results, the one-stage operation of aortic aneurysms and cancer resection is feasible if appropriate care is given to patients selection, technical details and the rules of antisepsis, without affecting surgical morbidity and mortality.

Aged↗
PubMed2002

On the theory of individual health.

On top of elaborate methods and approaches in research, diagnostics, and therapy, medicine is in need of a theory of its own thought and action; without theoretical reflection and referentiality, action becomes blind (and thus costly) and thought takes on a monotonous and circular character. Take the concept of health. The field of medicine, more and more taking its cues from evidence-based medicine (EBM), is onesidedly oriented to concepts of health which are based on notions of standard values for large populations or-in the shadow of the genome project-see health as the outcome of an intact genome, often turning a blind eye to the individual aspects of health. With an eye in particular to Friedrich Nietzsche's philosophy, the present paper looks into some continental European theories of individual health, seeking to determine to what extent they can contribute to reducing medicine's theory deficit and what consequences this may have for research, diagnostics, and therapy.

Ethical Theory↗
PubMed2002

Reliability and properties of ground Y-TZP-zirconia ceramics.

Yttria-stabilized zirconia ceramics is a high-performance material with excellent biocompatibility and mechanical properties, which suggest its suitability for posterior fixed partial dentures. The hypothesis under examination is that the strength and reliability of Y-TZP zirconia ceramics are affected by the inner surface grinding of crowns, and vary with the grinding parameter. Flexural strength, surface roughness, and fracture toughness were determined on samples machined by face and peripheral grinding with varied feed velocities and cutting depths. Results have been compared with those on lapped samples. Analysis of variance and Weibull parameter were used for statistical analysis. It was found that inner surface grinding significantly reduces the strength and reliability of Y-TZP zirconia compared with the lapped control sample. Co-analysis of flexural strength, Weibull parameter, and fracture toughness showed counteracting effects of surface compressive stress and grinding-introduced surface flaws. In conclusion, grinding of Y-TZP needs to be optimized to achieve the CAD/CAM manufacture of all-ceramic restorations with improved strength and reliability.

Algorithms↗
PubMed2001

Accumulation of cardiolipin and lysocardiolipin in fibroblasts from Tangier disease subjects.

Tangier disease (TD) is an inherited disorder of lipid metabolism characterized by very low high density lipoprotein (HDL) plasma levels, cellular cholesteryl ester accumulation and reduced cholesterol excretion in response to HDL apolipoproteins. Molecular defects in the ATP binding cassette transporter 1 (ABCA1) have recently been identified as the cause of TD. ABCA1 plays a key role in the translocation of cholesterol across the plasma membrane, and defective ABCA1 causes cholesterol storage in TD cells. Not only cholesterol efflux, but also phospholipid efflux was shown to be impaired in TD cells. By use of thin layer chromatography, high performance liquid chromatography and time-of-flight secondary ion mass spectrometry, we characterized the cellular phospholipid content in fibroblasts from three homozygous TD patients. The cellular content of the major phospholipids was not found to be significantly altered in TD fibroblasts. However, the two phospholipids cardiolipin and lysocardiolipin, which make up minute amounts in normal cells, were at least 3-5-fold enriched in fibroblasts from TD subjects. A structurally closely related phospholipid (lysobisphosphatidic acid) has recently been shown to be enriched in Niemann-Pick type C, another lipid storage disorder. Altogether these data may indicate that the role of these phospholipids is a regulatory one rather than that of a bulk mediator of cholesterol solubilization in sterol trafficking and efflux.

ATP Binding Cassette Transporter 1↗
PubMed2001

Accumulation of RhoA, RhoB, RhoG, and Rac1 in fibroblasts from Tangier disease subjects suggests a regulatory role of Rho family proteins in cholesterol efflux.

Tangier disease (TD) is an inherited disorder of lipid metabolism characterized by very low high density lipoprotein (HDL) plasma levels, cellular cholesteryl ester accumulation and reduced cholesterol excretion in response to HDL apolipoproteins. Molecular defects in the ATP binding cassette transporter 1 (ABCA1) have recently been identified as the cause of TD. ABCA1 plays a key role in the translocation of cholesterol across the plasma membrane, and defective ABCA1 causes cholesterol storage in TD cells. However, the exact relationship of many of the biochemical and morphological abnormalities in TD to ABCA1 is unknown. Since small GTP-binding proteins are important regulators of many cellular functions, we characterized these proteins in normal and TD fibroblasts using the [alpha-32P]GTP overlay technique and Western blotting of SDS and isoelectric focusing gels. Our results indicate that GTP-binding proteins of the Rho family (RhoA, RhoB, RhoG, Rac-1) are enriched in fibroblasts from TD patients. The accumulation of small G proteins may have potential implications for the TD phenotype and the regulation of cholesterol excretion in TD cells.

ATP Binding Cassette Transporter 1↗
PubMed2001

[Symptomatic aneurysm of the right gastroepiploic artery. Case report and review of the literature].

Aneurysms of the splanchnic arteries have rarely been reported. Aneurysms of the splenic artery are the most common aneurysms of the splanchnic vessels, followed by the hepatic and the mesenteric artery. Aneurysms of the gastroepiploic vessels show an incidence of only 0.4%. Due to a rupture rate of nearly 90% they are of great clinical importance. Therefore treatment is indicated for every diagnosed aneurysm of the gastroepiploic artery. While for ruptured aneurysms a conventional operation is inevitable, for asymptomatic aneurysms laparoscopic or interventional therapy is an alternative.

Abdomen, Acute↗
PubMed2001

[Results and complications of endovascular therapy of aortic aneurysms].

INTRODUCTION: Endovascular repair (ER) has been established as an alternative treatment option for aortic aneurysm (AA) in case of a suitable morphology. However, there are specific problems related to diagnostic and therapeutic management including potential complications of the new procedure. PATIENTS AND METHODS: Between 8/1996 and 11/1999, 41 patients (6 female, mean age 67.9 (range 55-84) years) underwent an operation with the intention of ER. Modular, self-expanding stent-grafts were used for aorto-biiliacal (36), aorto-monoiliacal (1), and aorto-aortal (infrarenal-1, thoracic-1) aortic aneurysm (AA) exclusion. Postoperatively and during the follow-up period, diagnostic measures included clinical investigation, native X-ray, and color-coded Doppler sonography, and spiral computed tomography, and digital subtraction angiography. Results were analysed with special reference to complications and resulting therapeutic consequences. RESULTS: Technical success was achieved in 36/41 patients (87.8%). There were 2 primary distal endoleaks and 3 conversions because of lacking vascular access. Of 4 primary endoleaks, a proximal one was treated successfully by overstenting, a distal one was sealed off by iliac extension, and 2 distal ones were treated conservatively. Three secondary endoleaks, a proximal and 2 distal ones, required conversion each by retro- and transperitoneal approach. Presently, there are 4 endoleaks, with the maximal aortic diameter remaining constant except one case. Five secondary occlusions of an iliac limb (4) or artery (1) were treated by thrombectomy (1), PTA (1), PTA with overstenting (1), and cross-over (1) or ilicofemoral bypass (1). Three patients died of unrelated disease during the follow-up period. DISCUSSION: On condition of a critical indication, improved diagnostic management and further refinement of stent-graft systems ER constitutes an alternative, minimally invasive treatment option for AA. Long-term results must be obtained by means of continued prospective and comparative studies to definitely evaluate ER.

Aged↗
PubMed2001

[Aneurysm of the femoral vein as differential diagnosis of femoral hernia].

Venous aneurysms are rare, especially those of the femoral vein. Groin hernias and femoral hernias are in contrast to this more frequent enteties. The literature includes only six cases of aneurysms of the femoral vein. We report on a 61-year-old patient who underwent an operation for femoral hernia. An aneurysm of the femoral vein was found intraoperatively and directly resected. The differential diagnosis of femoral hernias and the following diagnostic and therapeutic strategies are described.

Aneurysm↗
PubMed2001

Thoracic epidural anesthesia combined with general anesthesia: the preferred anesthetic technique for thoracic surgery.

UNLABELLED: Thoracic epidural anesthesia (TEA) combined with general anesthesia (GA) as well as total-IV anesthesia (TIVA) are both established anesthetic managements for thoracic surgery. We compared them with respect to hypoxic pulmonary vasoconstriction, shunt fraction and oxygenation during one-lung ventilation. Fifty patients, ASA physical status II-III undergoing pulmonary resection were randomly allocated to two groups. In the TIVA group, anesthesia was maintained with propofol and fentanyl. In the TEA group, anesthesia was maintained with TEA (bupivacaine 0.5%) combined with low-dose concentration 0.3-0.5 vol% of isoflurane (end-tidal). Changing from two-lung ventilation to one-lung ventilation caused a significant increase in cardiac output (CO) in the TIVA group, whereas no change was observed in the TEA group. One-lung ventilation caused significant increases in shunt fraction in both groups which was associated per definition with a significant decrease in PaO(2) in both groups but PaO(2) remained significantly increased in the TEA group (P < 0.05). We conclude that both anesthetic regimens are safe intraoperatively. However, TEA in combination with GA did not impair arterial oxygenation to the same extent as TIVA, which might be a result of the changes in CO. Therefore, patients with preexisting cardiopulmonary disease and impaired oxygenation before one-lung ventilation might benefit from TEA combined with GA. IMPLICATIONS: Fifty patients underwent lung surgery through the opened chest wall requiring ventilation of only one lung. Patients were randomly assigned to receive either general anesthesia alone or in combination with regional anesthesia via a catheter in the back. Oxygen content in the blood and blood pressure was better maintained in the group receiving the combination of general with regional anesthesia.

Adult↗
PubMed2001

Differential secretion of atrial and brain natriuretic peptide in critically ill patients.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones with natriuretic, vasorelaxant, and aldosterone-inhibiting properties. We analyzed the plasma of 178 critically ill patients for ANP, BNP, aldosterone, and serum sodium concentration, as well as serum and urine osmolality and sodium filtration fraction. Mean plasma concentrations of ANP and BNP were increased in critically ill patients compared with healthy controls (ANP, 14.3 +/- 5.8 pmol/L versus 8.8 +/- 3.2 pmol/L, P < 0.05; BNP, 26.2 +/- 10.7 pmol/L versus 4.6 +/- 2.8 pmol/L, P < 0.0001). The relative increases in ANP concentrations were comparable in all diseases. BNP concentrations, by contrast, showed a wider variation. The largest BNP concentrations were observed in patients who underwent cardiac surgical procedures and in patients with subarachnoid hemorrhage. ANP, but not BNP, was correlated with aldosterone levels (r = 0.4, P < 0.001), serum sodium (r = 0.42, P < 0.001), sodium filtration fraction (r = 0.3, P < 0.001), serum osmolality (r = 0.25, P < 0.01), urinary osmolality (r = -0.24, P < 0.01), and central venous pressure (r = 0.22, P < 0.01). ANP and BNP concentrations were increased in critically ill patients; however, this did not correlate with the severity of illness or mortality. Our data support a regulatory role for ANP in the maintenance of water and electrolyte balance. The physiologic role of BNP, by contrast, is less clear. ANP and BNP are not predictors for the severity of illness and mortality in critically ill patients.

APACHE↗
PubMed2001

Prolonged prodrome, systemic vasculitis, and deafness in Cogan's syndrome.

Cogan's syndrome is a rare, multisystem disease which occurs predominantly in children and young adults. It was originally described as the combination of interstitial keratitis and audiovestibular disturbance, but other forms of ocular disease, as well as systemic vasculitis, have since been recognised as part of the syndrome. Diagnosis can be difficult if the various manifestations occur separately, but early recognition is important because prompt treatment may prevent deafness. Two cases are presented here illustrating the features of this disease, and providing histological evidence of systemic vasculitis in both.

Adult↗
PubMed2001

Immunohistochemical detection of scrapie prion proteins in clinically normal sheep in Pennsylvania.

Following diagnosis of scrapie in a clinically suspect Suffolk sheep, 7 clinically normal flockmates were purchased by the Pennsylvania Department of Agriculture to determine their scrapie status using an immunohistochemical procedure. Two of the 7 euthanized healthy sheep had positive immunohistochemical staining of the prion protein of scrapie (PrP-Sc) in their brains, nictitating membranes, and tonsils. The PrP-Sc was localized in the areas of the brain where, histopathologically, there was neurodegeneration and astrocytosis. The PrP-Sc occurred within germinal centers of the affected nictitating membranes and tonsils and was located in the cytoplasm of the dendrite-like cells, lymphoid cells, and macrophages. These results confirm that immunohistochemical examination of the nictitating membrane can be used as a screen for the presence of scrapie infection in clinically normal sheep at a capable veterinary diagnostic laboratory. In sheep with a PrP-Sc-positive nictitating membrane, the diagnosis of scrapie should be confirmed by histopathology and immunohistochemical examination of the brain following necropsy. Following full validation, immunohistochemistry assays for detection of PrP-Sc in nictitating membrane lymphoid tissues can improve the effectiveness of the scrapie control and eradication program by allowing diagnosis of the disease in sheep before the appearance of clinical signs.

Animals↗
PubMed2001

High density lipoproteins induce cell cycle entry in vascular smooth muscle cells via mitogen activated protein kinase-dependent pathway.

In this study we found that HDL acts as a potent and specific mitogen in vascular smooth muscle cells (VSMC) by stimulating entry into S-phase and DNA synthesis in a time- and concentration-dependent manner, induction of cyclins D1, E, and A, as well as activation of cyclin D-dependent kinases as inferred from phosphorylation of the retinoblastoma protein (pRb). Moreover, HDL induced activation of the mitogen-activated protein kinase pathway including Raf-, MEK-1, and ERK1/2, as well as the expression of proto-oncogen c-fos, which is controlled by ERK1/2. PD98059, an inhibitor of MEK-1 blocked the mitogenic activity of HDL and cyclin D1 expression. HDL-induced VSMC proliferation, cell cycle progression, cyclin D1 expression, and activation of the Raf-1/MEK-1/ERK1/2 cascade were blocked by preincubation of cells with pertussis toxin indicating involvement of trimeric G-protein. By contrast, none of these responses was inhibited by the protein kinase C inhibitor, GF109203X. The mitogenic effects of native HDL were not mimicked by apo A-I, reconstituted HDL containing apo A-I, or cholesterol-containing liposomes. In conclusion, HDL possesses an intrinsic property to induce G-protein- and MAP-kinase-dependent proliferation and cell cycle progression in VSMC. The strong and specific mitogenic effect of HDL should be taken into account, when therapeutic strategies to elevate the plasma level of these lipoproteins are developed.

Animals↗
PubMed2000

Activation of phosphatidylinositol-specific phospholipase C by HDL-associated lysosphingolipid. Involvement in mitogenesis but not in cholesterol efflux.

Our earlier studies demonstrated that high-density lipoproteins (HDLs) stimulate multiple signaling pathways, including activation of phosphatidylcholine-specific phospholipases C and D (PC-PLs) and phosphatidylinositol-specific phospholipase C (PI-PLC). However, only activation of PC-PLs was linked to the HDL-induced cholesterol efflux. In the study presented here, the role of HDL-induced PI-PLC activation was studied. In human skin fibroblasts, HDL potently induced PI-PLC as inferred from enhanced phosphatidylinositol bisphosphate (PtdInsP(2)) turnover and Ca(2+) mobilization. The major protein component of HDL, apo A-I, did not induce PtdInsP(2) turnover or Ca(2+) mobilization in these cells. Both HDL and apo A-I promoted cellular cholesterol efflux, whereas only HDL induced fibroblast proliferation. Inhibition of PI-PLC with U73122 or blocking intracellular Ca(2+) elevation with Ni(2+) or EGTA markedly reduced the extent of HDL-induced cell proliferation but had no effect on cholesterol efflux. In fibroblasts from patients with Tangier disease which are characterized by defective cholesterol efflux, neither HDL-induced PtdInsP(2) breakdown and Ca(2+) mobilization nor cell proliferation was impaired. HDL-induced fibroblast proliferation, PtdInsP(2) turnover, and Ca(2+) mobilization were fully mimicked by the lipid fraction isolated from HDL. Analysis of this fraction with high-performance liquid chromatography (HPLC) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) revealed that the PI-PLC-inducing activity is identical with two bioactive lysosphingolipids, namely, lysosulfatide (LSF) and sphingosylphosphorylcholine (SPC). Like native HDL, LSF and SPC induced PtdInsP(2) turnover, Ca(2+) mobilization, and fibroblast proliferation. However, both compounds did not promote cholesterol efflux. In conclusion, two agonist activities are carried by HDL. Apo A-I stimulates phosphatidylcholine breakdown and thereby facilitates cholesterol efflux, whereas LSF and SPC trigger PI-PLC activation and thereby stimulate cell proliferation.

Apolipoprotein A-I↗
PubMed2000

A placebo-controlled crossover trial of creatine in mitochondrial diseases.

To test the efficacy and safety of creatine (Cr) monohydrate in mitochondrial diseases, 16 patients with chronic progressive external ophthalmoplegia or mitochondrial myopathy were randomized in a crossover design to receive double-blind placebo or 20 g Cr/day for 4 weeks. Cr was well tolerated, but there were no significant effects with regard to exercise performance, eye movements, or activities of daily life. The power of this pilot study was limited and future multicenter trials are needed.

Adult↗