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Biomedical subjects

M Bauer

Publications and source records attributed to M Bauer.

At least 91 records · Page 5Linked to original sources
PubMed2000

Surgical treatment of a chest-wall penetrating left ventricular pseudoaneurysm.

This report describes the treatment of a patient who developed a chest-wall penetrating pseudoaneurysm 3 years after coronary bypass grafting and after the resection of a lateral wall left ventricular aneurysm twice. The patient presented with a pulsatile tumor in the left submammilar region. Surgery was done in deep hypothermia, with femoro-femoral cannulation and via a left anterolateral thoracotomy. The perioperative course was uneventful and the patient is still well 5 years after surgery.

Aged↗
PubMed2000

Reinforcing the conventional sternal closure.

Sternal infection is a devastating complication of heart surgery. It may be the result of unstable osteosynthesis, caused by the sternal wires cutting into the cortical layers, which results in tension loss and gap formation. We describe a technique that prevents the cerclages from cutting into the sternal plates and covers the sternum with a well-capillarized barrier of major pectoralis muscle.

Aged↗
PubMed2000

The biocompound method in coronary artery bypass operations: surgical technique and 3-year patency.

BACKGROUND: Complete arterial revascularization may be unsafe in patients with a high operative risk. In patients with varicose ectatic veins, the biocompound technique, which uses unsuitable autologous veins, enables the surgeon to influence the bypass graft wall stress levels and diameter. This report summarizes the 3-year patency of 53 patients, the survival rate of 200 patients, and operative technical considerations. METHODS: Biocompound grafts were used for aortocoronary bypass in 200 patients who were considered inappropriate subjects for complete arterial revascularization and who had unsuitable saphenous veins. RESULTS: The mortality rate (30 days) of 200 patients was 3.5%. The 3-year survival rate was 88.5%. The patency rate of the left internal thoracic artery (LITA) after 3 years was 97.3%, of the native vein was 68.7%, and of the biocompound graft was 68.3%. The LITA showed a superior patency rate (p = < 0.05). CONCLUSIONS: The LITA is the first choice in coronary bypass operation. The biocompound technique is a reliable method to achieve complete revascularization in patients with a lack of suitable saphenous veins.

Aged↗
PubMed2000

Hirudin as anticoagulant for cardiopulmonary bypass: importance of preoperative renal function.

BACKGROUND: Recombinant hirudin is an alternative anticoagulant for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II. Although there is no neutralizing agent for recombinant hirudin, its fast renal elimination enables quick cessation of bleeding after cardiopulmonary bypass. The aim of the study was to compare anticoagulant effects of recombinant hirudin in regards to renal function in patients with heparin-induced thrombocytopenia type II. METHODS: Twenty-one patients (mean age, 65 years, and range, 35 to 82 years) underwent different complex cardiovascular procedures using recombinant hirudin as the anticoagulant for cardiopulmonary bypass. Postoperative blood loss, transfusion requirements, and hemostatic variables were compared between patients with a creatinine level lower than 1.5 mg/dL (group 1, normal renal function; n = 17 patients) and those with a creatinine level greater than 1.5 mg/dL (group 2, impaired renal function; n = 4 patients). RESULTS: The patients in group 1 showed no increased tendency toward postoperative bleeding. In contrast, all 4 patients in group 2 required reexploration for increased postoperative bleeding. They had higher activated partial thromboplastin times and transfusion requirements postoperatively. CONCLUSIONS: If recombinant hirudin is used as the anticoagulant for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and impaired renal function, the risk of postoperative bleeding is increased.

Adult↗
PubMed2000

Flexible bronchoscopy: a safe method for metal stent implantation in bronchial disease.

BACKGROUND: Endoscopic bronchoplastic procedures, such as metal stent implantation, are for safety reasons and mainly performed using rigid bronchoscopy. Major complications, such as bleeding and accidental airway occlusion, are thought to be better managed with the rigid device. An increasing number of pneumologists, however, use the flexible fiberscope for endobronchial stenting. METHODS: Sixty-five stent implantations were performed in 51 patients with flexible fiberoptic bronchoscopy. We implanted 27 Tantalum Strecker stents (Boston Scientific Co, Watertown, MA), 20 Nitinol Accuflex stents (Boston Scientific Co) and 18 Wallstents (Schneider, Zurich, Switzerland). Underlying conditions were malignant disease in 84% and benign bronchial collapse in 16%. Sites of implantation were the trachea (45%), the main bronchi (35%), and other locations (20%). In 47 cases the patients received intravenous sedation combined with high frequency jet ventilation, and in 18 cases the patients were treated with topical anesthesia alone. RESULTS: Mean examination time was 58.3 (standard deviation 29.1) minutes. Eighty percent of patients experienced immediate clinical improvement in respiratory symptoms. Spirometric parameters (forced expiratory volume in one second, peak expiratory flow rate, forced vital capacity) increased. Complications included hypertension (17%), hypotension (12%), hypoxia (5%), bronchospasm (4%), initial displacement of the prosthesis (11%), and diameter mismatch between stent and bronchus (5%). All complications were managed safely. Relevant bleeding or asphyxia during the procedure has not been observed. Late stent migration was observed in 12% of cases. There were 3 fatalities within 30 days of stent placement which, however, were not attributed to the implantation technique. CONCLUSIONS: Flexible fiberoptic bronchoscopy is a safe and suitable method to perform endobronchial metal stent implantation. Complications were rare and not serious. Initial misplacement of the prosthesis occurred in some cases and necessitated removal and replacement within the same procedure.

Adult↗
PubMed2000

Space- and time-resolved Brillouin light scattering from nonlinear spin-wave packets

We have constructed a new Brillouin light scattering apparatus, based on the Sandercock multipass tandem interferometer design, for space- and time-resolved investigations of nonlinear wave packets in thin films. We have applied the method to studies of nonlinear spin-wave pulse propagation in yttrium iron garnet (YIG) films. Spatial resolution is achieved by scanning the laser spot across the YIG film surface, and temporal resolution is obtained by measuring the elapsed time between the launch of spin-wave pulses by an applied microwave pulse and the arrival of the respective inelastically scattered photons at the detector. We report the observation of nonlinear self-focusing of wave beams and pulses in one and two dimensions, the formation of one-dimensional envelope solitons, and of strongly localized, two-dimensional wave packets, 'spin-wave bullets', analogous to 'light bullets' predicted in nonlinear optics. By generating two counter-propagating wave pulses, pulse collision experiments were performed. We show that quasi-one-dimensional envelope solitons formed in narrow film stripes ('waveguides') retain their shapes after collision, while two-dimensional spin-wave packets formed in wide YIG films are destroyed in collision.

Journal Article↗
PubMed2000

Maintenance therapies for classic and other forms of bipolar disorder.

The progressive, episodic and chronic nature of bipolar disorder dictates the need for lifelong pharmacological maintenance treatment in the majority of patients. Prophylaxis should be considered after a single episode of severe mania or after more than one episode of hypomania in bipolar II disorder, although some clinicians now consider an episode of either sufficient to warrant maintenance therapy. Lithium is efficacious as maintenance therapy, but is not as highly effective as early studies initially suggested (abrupt discontinuation of lithium probably increased placebo relapse figures). Rates of premature discontinuation of lithium are high. Divalproex sodium is used frequently in the USA and Canada for long-term treatment for bipolar disorder but an insufficient number of controlled trials have been published to assess adequately its role. Carbamazepine is also employed in maintenance treatment. Randomized studies indicate it is superior to placebo but somewhat less effective than lithium. Augmentation of any of these drugs with another mood stabilizer, an antipsychotic, or electroconvulsive therapy appears to be effective, although there are few controlled studies. Design issues that need consideration in order to achieve meaningful data are discussed. A severe manifestation of bipolar disorder is rapid cycling. It is often induced by antidepressants, although this association frequently goes unrecognized. Patients with a rapid cycling course of illness are difficult to treat effectively. Although rapid cycling is often associated with poor response to lithium, there have been no randomized, controlled treatment studies. Based on open studies and expert panel recommendations, the International Exchange on Bipolar Disorder (IEBD) recommended initial treatment with divalproex sodium, with subsequent addition of other mood stabilizers, antipsychotics or thyroid supplementation as necessary. Combination treatments are frequently required for optimal response in these patients.

Antidepressive Agents↗
PubMed2000

Transcriptional activation of heme oxygenase-1 and its functional significance in acetaminophen-induced hepatitis and hepatocellular injury in the rat.

BACKGROUND/AIM: Glutathione depletion contributes to acetaminophen hepatotoxicity and is known to induce the oxidative stress reactant heme oxygenase-1. The metabolites of the heme oxygenase pathway, biliverdin, carbon monoxide, and iron may modulate acetaminophen toxicity. The aim of this study was to assess cell-type specific expression of heme oxygenase-1 and its impact on liver injury and microcirculatory disturbances in a model of acetaminophen-induced hepatitis. METHODS: Gene expression of heme oxygenase-1 was studied by Northern- and Western analysis as well as immunohistochemistry. The time course of heme oxygenase-1 and -2, cytokine-induced neutrophil chemoattractant-1, and intercellular adhesion molecule-1 was studied by Northern analysis. DNA-binding activity of nuclear factor-kappaB was determined by electrophoretic mobility shift assay. Sinusoidal perfusion and leukocyte-endothelial interactions were assessed by intravital microscopy. RESULTS: Acetaminophen caused a moderate sinusoidal perfusion failure (-15%) and infiltration of neutrophils along with activation of nuclear factor-kappaB and intercellular adhesion molecule-1 and cytokine-induced neutrophil chemoattractant-1 mRNAs. Induction of heme oxygenase-1 mRNA and protein (approximately 30-fold) in hepatocytes and non-parenchymal cells paralleled the inflammatory response. Blockade of heme oxygenase activity with tin-protoporphyrin-IX abrogated acetaminophen-induced hepatic neutrophil accumulation and nuclear factor-kappaB activation, but failed to affect sinusoidal perfusion and liver injury. CONCLUSIONS: The inflammatory response associated with acetaminophen hepatotoxicity is modulated by the parallel induction of the heme oxygenase-1 gene. However, heme oxygenase-1 has no permissive effect on sinusoidal perfusion and does not affect liver injury in this model. These data argue against a central role of nuclear factor-kappaB activation and neutrophil infiltration as perpetuating factors of liver injury in acetaminophen toxicity.

Acetaminophen↗
PubMed2000

Ossiculoplasty: autogenous bone grafts, 34 years experience.

A series of 785 bone grafts between the tympanic membrane and head of the stapes were performed between 1964 and 1998. Ears were divided into 'normal tympanic membrane', 'stage I' and 'stage II' groups, in which the averages of the last postoperative air-bone gaps were 13.2, 18.7 and 18.1 dB, respectively (revision operations included). In the same order 43%, 26% and 23% of the ears showed air-bone gaps equal to or smaller than 10 dB; 85%, 61% and 67% equal to or smaller than 20 dB. Failures specific to the bone columella necessitated nine revision operations (eight for osseous fixation and one for atrophy). There have been no extrusions so far. Although, in the light of the literature the results are acceptable there is room for improvement.

Adolescent↗
PubMed2000

CpG-oligodeoxynucleotides enhance T-cell receptor-triggered interferon-gamma production and up-regulation of CD69 via induction of antigen-presenting cell-derived interferon type I and interleukin-12.

Bacterial cytidine-phosphate-guanosine (CpG-DNA) activates antigen-presenting cells (APC) and drives T helper 1 (Th1)-polarized immune responses in the mouse. Claims have been made that CpG-DNA costimulates murine T cells. We examined the direct and indirect effects of CpG-oligodeoxynucleotides (CpG-ODN) on human T-cell activation. CpG-ODN failed to costimulate purified human T cells activated with alpha-CD3 or alpha-T-cell receptor (TCR)alphabeta antibodies. In contrast, CpG-ODN sequence-specifically caused increased expression of CD69 on CD4 and CD8 T cells when peripheral blood mononuclear cells (PBMC) were stimulated via alpha-CD3. CpG-ODN and alpha-CD3 stimulation synergized to induce interferon-gamma (IFN-gamma) in T cells and natural killer (NK) cells, as shown by intracellular fluorescence-activated cell sorter (FACS) staining. These effects of CpG-ODN on human T cells were caused by the release of IFN type I (IFN-I) and interleukin-12 (IL-12) from PBMC. Enhancement of CD69 expression on alpha-CD3-triggered T cells could be reproduced in a coculture transwell system of purified T cells and PBMC, was inhibited by neutralizing antibodies to IFN-I and could be mimicked by adding exogenous IFN-I. Furthermore, neutralization of either IFN-I or IL-12 diminished, and in combination abolished, IFN-gamma production. These findings show that CpG-ODN potentiate TCR-triggered activation of human T cells in an APC-dependent manner.

Adjuvants, Immunologic↗
PubMed2000

Functional significance of endothelin B receptors in mediating sinusoidal and extrasinusoidal effects of endothelins in the intact rat liver.

Endothelins (ET) are important regulators of the hepatic microcirculation that act through different receptor subtypes. We investigated functional significance of ET(B) receptors in mediating microhemodynamic effects of ETs in normal and endotoxin (lipopolysaccharide [LPS])-primed rat liver. LPS priming (Escherichia coli O26:B6; 1 mg. kg(-1)) selectively increased ET(B) mRNA and led to a shift in available receptors to the ET(B) subtype. IRL 1620 (an ET(B) agonist) increased portal pressure in a dose-dependent manner, and the increase in ET(B) expression was associated with prolonged portal pressor response in isolated livers. However, lactate dehydrogenase (LDH) release was attenuated and sinusoidal blood flow was better maintained upon ET(B) stimulation in vivo. In isolated livers, portal constriction as well as release of LDH, were substantially increased in the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS). In vivo microscopic assessment of sinusoidal perfusion during ET(B) stimulation revealed a disruption of the flow pattern including frequent reversal of the flow direction without significant sinusoid constriction. Sinusoidal flow decreased even further after discontinuation of IRL 1620. Both effects were mediated at extrasinusoidal sites that probably included postsinusoidal sites. However, after pretreatment with L-NAME, IRL 1620 evoked a significant sinusoidal constriction that colocalized with the body of the stellate cell. We propose that ET(B1)-induced NOS activity attenuates ET(B2) (and presumably ET(A))-mediated portal pressor response and stellate cell constriction. Transcriptional activation of the ET(B) gene may have a permissive effect on liver blood flow and protect against hepatocellular damage under pathophysiological conditions associated with endotoxemia.

Animals↗
PubMed2000

The correction of congenital heart defects with less invasive approaches.

BACKGROUND: The minimally and less invasive approaches for the surgical treatment of different heart diseases are rapidly increasing because of their cosmetic and recovery-related advantages. Presented here are the results of less invasive surgery in 51 patients with congenital heart defects. METHODS: From June 1996 to January 1999, we used less invasive techniques for the correction of congenital heart defects in 51 patients. In 32 patients, we performed right anterolateral thoracotomy (6-13 cm), and on the other 19 patients, we used the partial inferior sternotomy (4-7 cm). The ascending aorta and the caval veins were cannulated in all patients. RESULTS: The following congenital heart defects were corrected: ostium secundum atrial septal defect (n = 35), sinus venosus atrial septal defect with partial anomalous pulmonary venous connection (n = 7), ventricular septal defect (n = 7), tetralogy of Fallot (n = 1), and cor triatriatum sinistrum (n = 1). The average age of the patients was 15 years old ranging from 2 months to 48 years and the average weight 39.6 kg (range 3.8-86 kg). The patients were removed from artificial respiratory support on average 8 hours (range 1-48 hours) after surgery and left the hospital after 7 days (range 2-10 days). In 16 patients, blood transfusions were required, an average 5.7 ml/kg BW (range 1.45-19.75 ml/kg BW). The postoperative course was uneventful in all patients. Follow-up (range 3-33 months, mean 17.5 months) was complete with no late deaths or residual defects. CONCLUSION: The right anterolateral thoracotomy and the partial inferior sternotomy provide a safe approach for the correction of certain congenital heart defects. These techniques enable operative correction without any additional risks being incurred and can be performed with standard instruments and cannulation. Additional approaches for extracorporeal circulation are unnecessary.

Adolescent↗
PubMed2000

Coexistence of intestinal trefoil factor (hITF) and oxytocin in magnocellular neurons in the human hypothalamus.

Human intestinal trefoil factor hITF, a polypeptide of the P-domain family, was found to occur in hypothalamic neurons. With combined immunofluorescence and immunoperoxidase technique we investigated the coexistence of hITF with the neurohypophysial peptide oxytocin and the associated neurophysin I in sections of the human hypothalamus. In the supraoptic nucleus, 39.2% of magnocellular oxytocinergic perikarya show hITF immunoreactivity. A similar distribution was observed in perivascular hypothalamic oxytocinergic neurons, whereas in the paraventricular nucleus, 99% of the oxytocinergic neurons show hITF coexpression. In the periventricular nucleus (PEV), single, scattered neurons with both immunoreactivities occur. Our findings indicate that hITF and oxytocin are coexpressed in a portion of the magnocellular neurons in the human hypothalamus, and that hITF is among the neurohypophysial peptides.

Aged↗
PubMed2000

A quick assay for monitoring recombinant hirudin during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II : adaptation of the ecarin clotting time to the act II device.

BACKGROUND: Recombinant hirudin is increasingly advocated as a promising alternative anticoagulation for patients with heparin-induced thrombocytopenia type II during cardiopulmonary bypass. This requires monitoring of the ecarin clotting time. No commercial ecarin clotting time assay is available for clinical use. We adapted the ecarin clotting time to the easy-to-handle ACT II device. METHODS: Three different concentrations of the ecarin reagent (20, 10, 5 U/mL) were investigated as preliminary studies. Standard calibration curves were constructed for concentrations of recombinant hirudin ranging from 0 to 5 microgram/mL. In vivo samples were collected from patients with heparin-induced thrombocytopenia type II who underwent cardiopulmonary bypass, and the values were compared with the values obtained by the chromogenic method. The final concentration for the assay of 5 IU/mL ecarin was further assessed in vitro for reproducibility and the influence of variations in hematocrit, platelet count, and procoagulants. RESULTS: All three concentrations of ecarin revealed linearity to 5 microgram/mL concentrations of recombinant hirudin. The ecarin concentration of 5 U/mL revealed the best correlation (0.87) to the laboratory method, was reproducible over the whole recombinant hirudin range, and was not influenced by the variations in the in vitro setup. CONCLUSIONS: The ACT II/ecarin clotting time with an ecarin concentration of 5 U/mL is a simple and reliable assay for monitoring recombinant hirudin during cardiopulmonary bypass. Use of this assay allows a wider use of recombinant hirudin in patients with heparin-induced thrombocytopenia type II during bypass and thereby may contribute to the safer management of these patients.

Anticoagulants↗
PubMed2000

Complicated chronic pancreatitis causing mycotic aortic aneurysm: in situ replacement with a cryopreserved aortic allograft.

Mycotic aortic aneurysm, which resulted from infected pancreatic pseudocysts with retroperitoneal abscess, developed in a patient with chronic pancreatitis. The aorta was approached through median laparotomy. Necrotic material was debrided from the pancreatic pseudocysts, and the mycotic aneurysm was resected. The aorta was replaced in situ with a cryopreserved aortic allograft. This report discusses the rare complication of pancreatic pseudocysts, which affect the infrarenal abdominal aorta and cause a large mycotic aneurysm. This case suggests that the use of cryopreserved allografts is promising for in situ reconstruction, even in a grossly infected field.

Aneurysm, Infected↗
PubMed2000

Endotoxin desensitization of human mononuclear cells after cardiopulmonary bypass: role of humoral factors.

BACKGROUND: The ability of leukocytes to release proinflammatory cytokines on lipopolysaccharide stimulation in vitro is impaired after cardiopulmonary bypass (CPB). This study tested contribution and interaction of humoral factors in altered leukocyte responsiveness to lipopolysaccharide. METHODS: Whole blood and isolated peripheral-blood mononuclear cells (PBMCs) from 10 patients obtained after induction of anesthesia (T1) and 20 min (T2) and 24 h (T3) after CPB were cultured in the absence or presence of lipopolysaccharide and assessed for release of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta and their functional antagonists, IL-1 receptor antagonist (IL-1ra) and IL-10. In addition, dose-response characteristics and interaction of IL-10 and norepinephrine as modulators of TNF-alpha release were studied. RESULTS: Cardiopulmonary bypass induced release of antiinflammatory (T2: IL-10: median 25 pg/ml, 25th-75th percentile 9-42; IL-1ra: median 1,528 pg/ml, 25th-75th percentile 1,075-17,047; P < 0.05 compared with T1) but failed to induce proinflammatory cytokines (T2: TNF-alpha: median 0 pg/ml, 25th-75th percentile 0-6; IL-1beta: median 1 pg/ml, 25th-75th percentile 0-81; nonsignificant). Removal of plasma at T2 increased TNF-alpha response to lipopolysaccharide (+83.8%; P < 0.05), whereas it suppressed IL-10 (-36.8%; P < 0.05). Similarly, incubation of PBMCs (T1) with plasma obtained after CPB (T2) as well as addition of IL-10 or norepinephrine in concentrations present in plasma after CPB led to a reduced lipopolysaccharide-stimulated TNF-alpha and an increased IL-10 response. Coadministration of norepinephrine and IL-10 had synergistic effects. Although pretreatment with an anti-IL-10 antibody and labetalol before addition of plasma obtained at T2 largely restored the TNF-alpha response in vitro, their addition post-treatment failed to restore the monocytic TNF-alpha response. CONCLUSIONS: Plasma contains interacting factors that inhibit the release of TNF-alpha and increase the release of IL-10, presumably attenuating the inflammatory response to CPB. Although norepinephrine fails to induce a cytokine response in the absence of other stimuli, its administration seems to augment the antiinflammatory IL-10 response while attenuating the TNF-alpha response.

Adult↗