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Biomedical subjects

G Bertsch

Publications and source records attributed to G Bertsch.

At least 19 recordsLinked to original sources
PubMed1999

Isolation of full-size mRNA from cells sorted by flow cytometry.

Gene expression is one key mechanism to regulate cell growth and differentiation. It is usually determined by Northern blotting or RT-PCR. However, studies with primary cell cultures are frequently hampered due to contaminating cells such as fibroblasts. We have developed a method to isolate intact full-size mRNA from sorted cells. In many cell types, e.g. cardiac myocytes, cell sorting without prior fixation revealed complete RNA breakdown. Based on a murine fibroblast cell line (AKR-2B), ethanol and formaldehyde at various concentrations and pre-treatment with ribonuclease inactivating DEPC were compared with each other. Fixation with 75% ice-cold DEPC-pre-treated ethanol for 5 min yielded mostly intact RNA. In contrast, antibody staining prior to sorting required 15 min fixation. Addition of RNAse-free BSA (0.5%) and 2 mM CaCl2 optimised the cell recovery ratio and thus a better RNA yield (60% compared to control) after sorting than former studies. Northern blotting and RT-PCR show the intact mRNA species beta-actin. Furthermore, dependent on the cellular PCNA content, we have demonstrated the cell cycle dependent cdk2 and cyclin A expression. This fast and reliable method allows to isolate intact full-size mRNA species appropriate for Northern blotting and RT-PCR to monitor gene expression.

Animals↗
PubMed1999

Intralobar lung sequestration with systemic coronary arterial supply.

Pulmonary sequestration is a rare anomaly. An accurate pre-operative evaluation of its vascular supply is essential for the surgeon's operative approach. We describe here an intrapulmonary sequestration with vascular arterial supply via the left circumflex and the right coronary artery. This case demonstrates that if aortography is unrevealing, then a coronary source should be considered in the preoperative search for the arterial supply to a pulmonary sequestration. Moreover, pulmonary sequestration should be listed in the differential diagnosis of aberrant coronary arteries.

Bronchopulmonary Sequestration↗
PubMed1999

Detection of myocardial viability by low-dose dobutamine Cine MR imaging.

The purpose of this work was to test the diagnostic value of dobutamine stress magnetic resonance imaging (MRI) for predicting recovery of regional myocardial contractility after revascularization. Cardiac wall motion abnormalities are due to either non-viable and/or scarred, or viable, but hibernating, myocardial tissue. Dobutamine stress leads to increased systolic wall thickening only in viable myocardium. Twenty-five patients with akinetic or dyskinetic myocardial regions were examined with a Cine FLASH-2D sequence at rest and during dobutamine stress (10 microg/kg/min). Patients were re-examined at rest 3, and in case of persisting wall motion defects, 6 months after revascularization. Criterion of viability was increasing end-systolic wall thickening during stress and/or at follow-up. Akinetic regions related either to the LAD (n = 19) or to the RCA (n = 6) were judged viable if > or = 50% of the affected segments improved. MR studies were completed in all subjects without arrhythmia or need for early terminations due to symptoms. Sensitivity, specificity, and positive predictive value for the prediction of myocardial viability were 61%, 90%, and 87% for the segment-related analysis, and 76%, 100%, and 100% for the patient-related analysis based on coronary artery distribution, respectively. Dobutamine stress MRI allows to predict global functional recovery of akinetic myocardial regions after revascularization with a high positive predictive value and high specificity.

Adult↗
PubMed1997

Cell death of AKR-2B fibroblasts after serum removal: a process between apoptosis and necrosis.

AKR-2B cells disintegrate after serum removal. After a delay of approximately 90 minutes, cell death began and reached after six hours a plateau of 40-50% remaining living cells. We used time-lapse video microscopy to monitor dynamic structural changes and to measure the time span of individual cells to die. The first change was the rapid appearance of membrane blebs. Membrane vesicles were rapidly extruded and reintegrated by the cell. This highly dynamic process of an affected cell stopped after 80+/-20 minutes with its death. Conductivity measurements showed that at that time the membrane was electrically permeable. By using fluorescence double staining with propidium iodide and Hoechst 33258, we show that membrane leakage leading to disintegration is accompanied, and for some cells preceded, by nuclear condensation. The energy state of the intact cells was monitored by measuring the intracellular ATP content which remained high (6 mM) throughout the entire time of investigation. Mitochondrial potential was determined by rhodamine 123 fluorescence in parallel to the measurement of membrane permeability via uptake of propidium iodide and lead to the detection of a cell population that exhibits a high mitochondrial potential and an uptake of propidium iodide indicating a membrane disruption of cells which still have a high energy charge. It is shown by electron microscopy that mitochondria were swollen and damaged in parallel to nuclear condensation. There was no DNA fragmentation as shown by two independent methods. Addition of the ICE-like protease inhibitor tyr-val-ala-asp-chloromethylketone immediately after serum starvation lead to an almost complete survival of the cells up to 6 hours. A pronounced protection was still observed after 24 hours, suggesting an involvement of this type of protease in the onset of cell death after serum removal. Apparently, serum withdrawal activates a succession of initial events that are similar to those defined as 'apoptosis', i.e. nuclear condensation and membrane blebbing. These steps are, however, accompanied or rapidly followed by cell lysis and disruption of mitochondria, both of which are characteristic of necrosis.

Adenine Nucleotides↗
PubMed1997

Cardiac high-energy phosphate metabolism in patients with aortic valve disease assessed by 31P-magnetic resonance spectroscopy.

BACKGROUND: The purpose of this work was to determine the clinical and hemodynamic correlates of alterations in cardiac high-energy phosphate metabolism in patients with aortic stenosis and with aortic incompetence. METHODS: Fourteen volunteers, 13 patients with aortic stenosis, and 9 patients with aortic incompetence were included. Patients underwent echocardiography and left and right heart catheterization. 31P-MR spectra from the anterior myocardium were obtained with a 1.5 Tesla clinical MR system. RESULTS: Aortic stenosis and aortic incompetence patients had similar New York Heart Association (NYHA) classes (2.77 +/- 0.12 vs 2.44 +/- 0.18), ejection fractions (normal), left ventricular (LV) end-diastolic pressures, and LV wall thickness. In volunteers, phosphocreatine/adenosine triphosphate (ATP) ratios were 2.02 +/- 0.11. For all patients, phosphocreatine/ATP was significantly reduced (1.64 +/- 0.09; *p = 0.011 vs volunteers). Phosphocreatine/ATP decreased to 1.55 +/- 0.12 (*p = 0.008) in aortic stenosis, while in aortic incompetence, phosphocreatine/ATP only showed a trend for a reduction (1.77 +/- 0.12; p = 0.148). For all patients, phosphocreatine/ATP decreased significantly only with NYHA class III (1.51 +/- 0.09; *p = 0.001), but not with NYHA classes I and II (phosphocreatine/ATP 1.86 +/- 0.18). In aortic stenosis, phosphocreatine/ATP ratios decreased (1.13 +/- 0.03; *p = 0.019) only when LV end-diastolic pressures were > 15 mm Hg or when LV diastolic wall stress was > 20 kdyne cm-2 (1.13 +/- 0.03; *p = 0.024). CONCLUSIONS: For a similar clinical degree of heart failure in human myocardium, volume overload hypertrophy does not, but pressure overload does, induce significant impairment of cardiac high-energy phosphate metabolism. In aortic valve disease, alterations of high-energy phosphate metabolism are related to the degree of heart failure.

Adenosine Triphosphate↗
PubMed1996

[Elective coronary implantation of a newly developed stent without conventional anticoagulation].

OBJECTIVE: To assess in an open prospective study the angiographic and clinical results of the elective implantation of the recently developed AVE micro-stent (Applied Vascular Engineering, Santa Rosa, CA, USA), in combination with dual antiaggregation treatment. PATIENTS AND METHODS: Between January and December 1995 AVE micro-stents were implanted into 128 vessels in 121 patients (20 women, 101 men; mean age 60.7 +/- 9.5 [34-84] years) with symptomatic coronary heart disease (CHD). Indication for the primary implantation of the stent type was a complex morphology of the stenosis with unfavourable short- and long-term prognosis. The stent consists of a 4 mm long tubular highly flexible segment made of 0.008 inch wire and can be advanced even into tortuous vessels. After balloon dilatation of the stenosis the stent was advanced into the vessel wall at a pressure of 10-12 bar, followed by further dilatation at 16-18 bar. Conventional long-term anticoagulation was dispensed with, patients only receiving antiaggregation medication: 500 mg ticlopidine and 100 mg aspirin daily for 6 weeks. RESULTS: The primary success rate of stent implantation was 99% (121 of 122). Neither acute nor subacute thromboses were revealed during hospital stay nor was there any emergency bypass operation or early repeat balloon angioplasty. There were no abnormal bleedings. CONCLUSION: Stenoses which are unsuitable for conventional balloon angioplasty can be reliably treated with the AVE microstent. Optimal high-pressure dilatation in combination with dual antiaggregation treatment will prevent stent thrombosis and bleeding complications.

Adult↗
PubMed1996

Okadaic acid induces cellular hypertrophy in AKR-2B fibroblasts: involvement of the p70S6 kinase in the onset of protein and rRNA synthesis.

At low concentrations (50 nM), okadaic acid (OA), an inhibitor of phosphatases 1 and 2A, inhibits platelet-derived growth factor-induced cell proliferation in late G1 (A. Simm et al., Exp. Cell Res., 210: 160-165, 1994). This inhibition is caused by the interference of OA in the induction and activation of the cell division protein kinases cdk1 and cdk2. OA alone has no effect on cell number, but induces a pronounced increase in cell size. The OA-induced hypertrophy can be divided into two phases. The first phase is characterized by a swelling of the cells. This increase in cellular volume is not accompanied by a change in the level of cellular macromolecules, i.e., protein and RNA. Inhibitor studies indicated a possible role of the Na+/H+ antiporter and Cl- channels in this process. In the second phase, an increase in the cellular protein and RNA content was observed along with a minor change in cell volume. To delineate a possible signaling pathway, the involvement of numerous protein kinases was analyzed. Low concentrations of OA lead to pronounced and sustained activation of the p70S6 kinase. There was little or no effect on various other kinases that can be activated by extracellular signals, e.g., mitogen-activated kinase, ribosomal S6 kinase, or other S6 peptide kinases. Likewise, at these concentrations, OA did not activate the genes for fos, myc, or ornithine decarboxylase. At very low concentrations (ED50, 0.5 nM), rapamycin, a specific inhibitor of the activation of p70S6 kinase, reversed the activation of the p70S6 kinase and the enhancement of RNA synthesis and partially the increase in cell volume and protein synthesis. The OA-induced hypertrophy of AKR-2B fibroblasts may serve as a model system for investigations aimed at the identification of signaling pathways leading to hypertrophy of differentiated nonproliferating cells.

Adenine Nucleotides↗
PubMed1992

Who repeats? A follow-up study of state hospital patients' firesetting behavior.

The authors report on a population of psychiatric patients who were studied over a 6.75 year period to determine the occurrences of firesetting behavior noted in their psychiatric inpatient records. Two groups of 50 patients each were drawn from an earlier study and were matched by sex, age, and diagnoses. One group of patients had prior firesetting behavior; the other did not. Firesetting behavior was found not only in patients originally identified as having previously engaged in this behavior, but also in those with no documented history of this act prior to the period of the study. Patients having firesetting behavior in their past psychiatric record set more actual fires. Total number of episodes of firesetting behavior, however, was not significantly different between the two groups. Results are discussed in terms of the communicative function of firesetting and the dilemma of clinical prediction.

Female↗