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Biomedical subjects

J Herrmann

Publications and source records attributed to J Herrmann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Coronary vasa vasorum neovascularization precedes epicardial endothelial dysfunction in experimental hypercholesterolemia.

OBJECTIVE: Experimental hypercholesterolemia is associated with vasa vasorum neovascularization, unknown to occur before or after initial lesion formation. Thus, this study was performed to determine the temporal course of neovascularization of coronary vasa vasorum in relation to endothelial dysfunction, a hallmark of early atherosclerosis. METHODS: Female domestic pigs were fed a normal diet (Group 1), a hypercholesterolemic diet for 2 and 4 weeks (Group 2), or a hypercholesterolemic diet for 6 and 12 weeks (Group 3). In vitro analysis of relaxation response to bradykinin served as an index for epicardial endothelial function. Spatial pattern and density of coronary vasa vasorum were assessed by three-dimensional microscopic computed tomography. RESULTS: Relaxation response of coronary arteries to bradykinin was normal in both Group 1 (93+/-6%) and Group 2 (89+/-7%) but impaired in Group 3 (71+/-11%; P<0.05 vs. Group 1 and 2). In contrast, density of coronary vasa vasorum was significantly higher in both Group 2 (4.88+/-2.45 per-mm(2)) and Group 3 (4.50+/-1.37 per-mm(2)) compared to Group 1 (2.97+/-1.37 per-mm(2); P<0.05 vs. Group 2 and 3). CONCLUSION: This study demonstrates that coronary vasa vasorum neovascularization occurs within the first weeks of experimental hypercholesterolemia and prior to the development of endothelial dysfunction of the host vessel, suggesting a role for vasa vasorum neovascularization in the initial stage of atherosclerotic vascular disease.

Analysis of Variance↗
PubMed2001

Human telomerase reverse transcriptase antisense treatment downregulates the viability of prostate cancer cells in vitro.

Telomerase, a ribonucleoprotein complex is activated in the vast majority of human malignancies, including prostate cancer. Its inhibition is a putative way to affect cancer proliferation and might be used in the therapy of tumors. We analysed the influence of antisense phosphorothioate oligonucleotides (PTO) against the reverse transcriptase subunit of telomerase on prostate cancer cell viability, telomerase activity and telomere length. DU145 prostate cancer cells were cultivated in PTO containing medium. The PTO-incorporation was confirmed by confocal laser scanning microscopy. Cell viability was measured by a WST-1 tetrazolium assay. After 15 days of antisense PTO treatment, a significant inhibition of cell viability occurred. Telomerase activity was determined by a telomeric repeat amplification protocol (TRAP) assay and telomere length by Southern blot analysis. Since the long-term telomerase antisense treatment reduces the viability of prostate cancer cells significantly, this antisense approach could be a new therapeutic strategy to treat patients with advanced prostate cancer.

Blotting, Southern↗
PubMed2001

[Applied anatomy of the distal "vinculum tendinis" in the fetlock tendon sheath of the hindlimb in cattle].

A relatively thick (diameter approximately 2 mm), ropelike (length ca. 20 mm) and elastic "Vinculum tendinis" connects--within the fetlock tendon sheath--the dorsal side of the deep digital flexor tendon with the dorsal part of the Manica flexoria (the communicating band of the Musculus interosseous medius to the superficial digital flexor tendon). The extensive fetlock tendon sheath can be involved in diseases such as aseptic and septic inflammations. Spreading of these inflammations makes in some of these cases the partial resection of the tendon of the deep digital flexor muscle and the cutting of these Vincula necessary. The results of this contribution, collected from 60 hindlimbs of adult bovines show variations in number, length, diameter and extent and the inner structure with blood vessels and nerves.

Animals↗
PubMed2000

NMR structure and mutagenesis of the third Bir domain of the inhibitor of apoptosis protein XIAP.

The inhibitor of apoptosis proteins (IAPs) regulate the caspase family of cysteine proteases, which play an important role in the execution of programmed cell death. Human X-linked inhibitor of apoptosis protein (XIAP) is a potent inhibitor of caspases-3, -7, and -9. Here we show that the Bir3 domain is the minimal region of XIAP that is needed for potent caspase-9 inhibition. The three-dimensional structure of the Bir3 domain of XIAP, determined by NMR spectroscopy, resembles a classical zinc finger and consists of five alpha-helices, a three-stranded beta-sheet, and a zinc atom chelated to three cysteines and one histidine. The structure of the Bir3 domain is similar to that of the Bir2 domain of XIAP but differs from the previously determined structure of the Bir3 domain of MIHB. Based on site-directed mutagenesis, we have identified the regions of the Bir3 domain of XIAP that are important for inhibiting caspase-9. Despite the structural similarities of the Bir2 and Bir3 domain of XIAP, a different set of residues were found to be critical for inhibiting the individual caspases. These results suggest that XIAP inhibits caspase-3 and caspase-9 in a different manner.

Amino Acid Sequence↗
PubMed2000

Phase relations, quasicontinuous spectra and subfemtosecond pulses in high-order stimulated raman scattering with short-pulse excitation

High-order stimulated Raman scattering for pumping by ps and sub-ps pulses is studied in the frame of a time-domain approach without the slowly varying envelope approximation. Formation of pulse trains with sub-fs durations in the ps-pump regime is demonstrated using external phase compensation. For sub-ps excitation a novel broadening mechanism of Raman lines is predicted that leads to a quasicontinuous spectrum and permits one to generate single sub-fs pulses. We predict also essential shortening of a delayed fs-probe pulse by the Raman oscillations without phase control.

Journal Article↗
PubMed2000

Outbreak of Klebsiella pneumoniae producing transferable AmpC-type beta-lactamase (ACC-1) originating from Hafnia alvei.

Fifty-two strains of Klebsiella pneumoniae producing an AmpC-type plasmid-mediated beta-lactamase were isolated from 13 patients in the same intensive care unit between March 1998 and February 1999. These strains were resistant to ceftazidime, cefotaxime and ceftriaxone, but susceptible to cefoxitin, cefepime and aztreonam. Plasmid content and genomic DNA restriction pattern analysis suggested dissemination of a single clone. Two beta-lactamases were identified, TEM-1 and ACC-1. We used internal bla(ACC-1) primers, to sequence PCR products obtained from two unrelated strains of Hafnia alvei. Our results show that the ACC-1 beta-lactamase was derived from the chromosome-encoded AmpC-type enzyme of H. alvei.

Amino Acid Sequence↗
PubMed2000

Magnetic resonance imaging volumes of the hippocampus and the amygdala in women with borderline personality disorder and early traumatization.

BACKGROUND: Based on findings of stress-induced neural disturbances in animals and smaller hippocampal volumes in humans with posttraumatic stress disorder), we hypothesized that patients with borderline personality disorders (BPD), who often are victims of early traumatization, have smaller volumes of the hippocampus and the amygdala. We assumed that volumes of these brain regions are negatively correlated with traumatic experiences and with neuropsychological deficits. METHODS: We studied 21 female patients with BPD and a similar group of healthy controls. We performed clinical assessments, a modified version of the Childhood Trauma Questionnaire, and magnetic resonance imaging volumetric measurements of the hippocampus, amygdala, temporal lobes, and prosencephalon. Neuropsychological testing included scales on which disturbances in BPD were previously reported. RESULTS: The patients with BPD had nearly 16% smaller volumes of the hippocampus (P<.001) and 8% smaller volumes of the amygdala (P<.05) than the healthy controls. The results for both hemispheres were nearly identical and were controlled for the volume of the prosencephalon and for head tilts. The volumes of the hippocampus were negatively correlated with the extent and the duration of self-reported early traumatization only when BPD and control subjects were considered together. Levels of neuropsychological functioning were associated with the severity of depression but not with the volumes of the hippocampus. CONCLUSION: In female patients with BPD, we found reduction of the volumes of the hippocampus (and perhaps of the amygdala), but the association of volume reduction and traumatic experiences remains unclear. Arch Gen Psychiatry. 2000;57:1115-1122.

Adult↗
PubMed2000

Potential embolization by atherosclerotic debris dislodged from aortic wall during cardiac catheterization:: histological and clinical findings in 7,621 patients.

Embolic events during cardiac catheterization have been attributed to atherosclerotic aortic debris dislodged by catheter manipulation. We evaluated the frequency and the histologic morphology of atherothrombotic material retrieved during placement of coronary catheters in patients undergoing diagnostic or interventional cardiac procedures. Over a 4-year period, macroscopically visible aortic debris from coronary catheters, if present after advancement to the ascending aorta, was obtained for histologic examination. In 41 of 7,621 patients (0.54%), visible atherothrombotic material was present in the backflow of catheters. Debris occurred most frequently with 8 Fr guiding catheters (98%). Histologic examination showed foam cells, cholesterol crystals, and amorphic lipoid substance as markers of atheromatous material from atherosclerotic plaques in 38/41 patients (93%) with former plaque hemorrhage in 55% of them. In three patients, fresh thrombus material was observed (7%). None of these patients showed in-hospital ischemic complications. Although visible atheromatous material is a rare phenomenon in cardiac catheterization, an increased risk of scraping debris is associated with large-lumen guiding catheters. In order to avoid vascular embolization, the use of smaller guiding catheters and sufficient free backflow of catheters after advancement are recommended.

Adult↗
PubMed2000

Nonsurgical retrieval of embolized coronary stents.

Embolization of coronary stents before deployment is a rare but challenging complication of coronary stenting. Different methods for nonsurgical stent retrieval have been suggested. There were 20 cases (0.90%) of intracoronary stent embolization among 2,211 patients who underwent implantation of 4,066 stents. Twelve of 1,147 manually crimped stents (1.04%) and eight of 2,919 premounted stents were lost (0.27%, P < 0.01) during retraction of the delivery system, because the target lesion could not be either reached or crossed. Percutaneous retrieval was successfully carried out in 10 of 14 patients (71%) in whom retrieval was attempted. In 10 patients, stent retrieval was tried with 1.5-mm low-profile angioplasty balloon catheters (success in 7/10) and in seven cases with myocardial biopsy forceps or a gooseneck snare (success in 3/7). Three patients (15%) underwent urgent coronary artery bypass surgery after failed percutaneous retrieval, but their outcomes were fatal. In two patients, stents were compressed against the vessel wall by another stent, without compromising coronary blood flow. In two patients, a stent was lost to the periphery without clinical side effects; treatment was conservative in these cases. Embolization of stents before deployment is a rare but serious complication of coronary stenting, with hazardous potential for the patient. Manual mounting of stents is associated with a significantly higher risk of stent embolization. Stent retrieval from the coronary circulation with low-profile angioplasty balloon catheters is a readily available and technically familiar approach that has a relatively high success rate.

Aged↗
PubMed2000

Percutaneous transluminal laser guide wire recanalization of chronic subclavian artery occlusion in symptomatic coronary-subclavian steal syndrome.

Treatment of subclavian artery stenosis by percutaneous balloon angioplasty and adjunctive stent placement was shown to be safe and efficacious, but it may be limited in tight stenoses and long occlusions. We describe the case of a patient who experienced progressive angina pectoris associated with signs of cerebrovertebral insufficiency 9 yr after bypass surgery, including left internal mammary artery (LIMA) grafting to the left anterior descending coronary artery. Angiography showed reversed flow through the LIMA graft into the subclavian artery and a 4-cm occlusion beginning at the origin of the left subclavian artery, representing a rare coronary-subclavian steal syndrome. After a conventional approach failed, recanalization was performed successfully using laser guide wire angioplasty with adjunctive stent placement in a combined radial and femoral approach.

Angioplasty, Balloon, Laser-Assisted↗
PubMed2000

[Electromechanically controlled versus roengenologically guided percutaneous transluminal laser myocardial revascularization].

Transmyocardial laser revascularization is a modern therapeutic concept for patients with end-stage coronary artery disease not eligible for bypass surgery, percutaneous coronary interventions or heart transplantation. Although the principal idea of creating additional myocardial perfusion from the cavum of the left ventricle was derived from observations in reptile hearts, histological investigations suggest that channel patency is not the underlying mechanism for improved clinical symptoms. Sympathetic denervation and angioneogenesis may be additional explanations for improvement of angina and stress tolerance. The first experiences with transmyocardial laser revascularization were made using a surgical approach. Two randomized multicenter trials could show a significant improvement in angina and stress tolerance 12 months after creating channels using laser technique. While these results were obtained by performing thoracotomy, catheter-based systems have been designed for a less invasive approach of this technique. A further advantage of these new systems is that regions like the septum can be treated which are not eligible for a surgical approach. Using percutaneous transluminal catheter-based systems channels of up to 6 mm length can be created. Beside the fluoroscopic guided creation of myocardial channels a new mapping system has been applied using electromechanical features of viable myocardial tissue. This system is based on the observation that endocardial electrograms recorded from an infarcted area are characterized by very low amplitude and fractionated morphology. This system allows online mapping of viable myocardium and provides spatial, electrical, and mechanical information of the myocardium. This method of electromechanical mapping highly correlates with results obtained from myocardial perfusion scans. Recent preliminary clinical trials demonstrated that catheter-based creation of myocardial channels is a feasible and successful alternative to the surgical laser revascularization. Also with this approach a significant improvement in angina and stress tolerance can be achieved. The results of the PACIFIC study, the first randomized multicenter study using percutaneous transluminal laser revascularization, demonstrates that after 3 and 6 months more than half of the patients presented improved angina of at least 1 Canadian-Cardiovascular-Society class. Whether electromechanical guided myocardial laser revascularization is more efficient than fluoroscopic guided has not been proven yet. Further studies will have to evaluate this issue.

Animals↗
PubMed2000

Molecular characterization of STAT5A- and STAT5B-encoding genes reveals extended intragenic sequence homogeneity in cattle and mouse and different degrees of divergent evolution of various domains.

The STAT transcription factors form a family of signal transducers and activators of transcription. We sequenced the bovine STAT5B cDNA and both STAT5-encoding genes, STAT5A and STAT5B, representing the first complete description of any STAT5-encoding gene. DNA fiber FISH hybridization revealed that the genes reside only 40 kbp apart on BTA19. Both genes are segmented into 19 exons and all but two of the homologous exons are of equal size. The genes harbor a central block of nearly identical DNA sequence (97.5% sequence identity over 3373 bp), spanning from intron 5 to intron 9. Isolation and sequencing of the homologous segments from mouse revealed the same unusually high degree of intronic sequence conservation in these segments of the murine STAT5-encoding genes. However, the respective sequences are completely divergent between the two species. A comparison of the inter- and intragenic cDNA sequence preservation at nonsynonymous sites reveals that the DNA-binding domain is under the strongest selection pressure for both intergenic and factor-specific intragenic sequence preservation. The so-called "SH3" segment of the linker domain, in contrast, shows species-specific sequence identity in all but one amino acid residues in both factors, in cattle, human, and mouse. This indicates that the same species-specific selection pressure occurs on the linker domain from both factors, STAT5A and STAT5B. Thus, the comparison of evolutionary selection pressures resting on various domains suggests that the DNA-binding domain might contribute to differential DNA binding of STAT5A and STAT5B factors, while both might interact equally well with other cellular factors through a segment of the linker domain.

Amino Acid Sequence↗
PubMed2000

[Transluminal exclusion of a subclavian artery aneurysm with stent-graft implantation].

In a 73 year-old male patient with generalized atherosclerosis, known infrarenal abdominal aortic aneurysm, renal artery stenosis, and coronary artery disease, an aneurysm of the proximal left subclavian artery was successfully excluded by implantation of a JOSTENT-Peripheral stent graft. Angiographic follow up after 6 and 12 months showed an excellent outcome with complete exclusion of the aneurysm. Intravascular ultrasound showed no neo-intimal hyperplasia within the stent. A computed tomography revealed complete thrombosis of the aneurysm.

Aged↗
PubMed2000

Cystatin C, an early indicator for incipient renal disease in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic disease requiring potential nephrotoxic therapy with nonsteroidal antiinflammatory drugs (NSAIDs) and disease modifying antirheumatic drugs (DMARDs). The rationale of our study was to examine the renal status of patients suffering from prolonged RA by means of plasma cystatin C, a new parameter of renal function. Fifty-six patients affected with RA for more than 5 years, and treated with NSAIDs for more than 50 months, were included in the study. Besides conventional markers of renal function (i.e. plasma creatinine, estimated glomerular filtration rate, creatinine clearance), we analysed plasma cystatin C by an automated, nephelometric immunoassay on a Behring nephelometer. Sixty percent of the RA patients exhibited elevated levels of plasma cystatin C, whereas only three out of 56 patients showed an elevated plasma creatinine, even though the creatinine clearance was decreased in 57% of these patients. Cystatin C exhibited a by far better correlation with creatinine clearance than plasma creatinine. In conclusion, patients with prolonged RA for more than 50 months, show a disturbed renal function despite normal plasma creatinine. Elevated cystatin C indicates such incipient renal disease, and is, not least because of a simple, well reproducible technique, more recommendable for screening purposes than tedious clearance determinations.

Aged↗
PubMed2000

Dose-dependent effects of intracoronary verapamil on systemic and coronary hemodynamics.

Calcium antagonists are used in interventional cardiology to prevent coronary vasoconstriction or to overcome the no-reflow phenomenon. The aim of the current study was to evaluate the dose-dependent effects of intracoronary verapamil on systemic and coronary hemodynamics. In 20 patients scheduled for routine coronary angiography, heart rate, blood pressure, and ECG recordings were recorded continuously and intracoronary flow velocity was obtained by intracoronary Doppler measurements in angiographically normal vessels. The cross-sectional area, measured by quantitative coronary angiography, allowed the calculation of coronary blood flow (CBF) and the coronary vascular resistance index (CVRI). Without premedication, increasing dosages of verapamil (0.01 mg, 0.1 mg, 1.0 mg, and 2.0 mg) were injected into the left coronary artery. Intracoronary verapamil administration led to a decrease in systemic blood pressure only after administration of 1.0 mg or 2.0 mg (change in mean arterial pressure: from 87.6 +/-14.6 mmHg to 80.1 +/- 14.9 mmHg and 78.5 +/- 13.9 mmHg, respectively; both P < 0.05) without a change in heart rate. Epicardial diameters of the left coronary artery increased only at dosages of 1.0 mg and 2.0 mg (from 2.14 +/- 0.4 mm to 2.22 +/- 0.3 mm, P < 0.01), whereas the coronary blood flow velocity increased significantly at the smallest dosage of 0.01 mg (from 19.9 +/- 8.7 cm/s to 33.2 +/- 14.9 cm/s, P < 0.001) and was further enhanced with increasing dosages. CBF increased and CVRI decreased at every dosage of verapamil compared with baseline values. CBF increased also after 0.1 mg (from 13.5 +/- 6.5 mL/min to 19.5 +/- 9.3 mL/min; P < 0.05), reaching a maximal effect after administration of 1.0 mg verapamil (26.3 +/- 16.1 mL/min, P < 0.05). Application of 2.0 mg did not further increase CBF compared with 1.0 mg. Intracoronary application of verapamil leads to a decrease in systemic blood pressure at higher dosages, whereas heart rate remains unchanged at any dosage. The maximal increase in coronary blood flow and decrease in vascular resistance can be reached by administration of 1.0 mg verapamil into the left coronary artery.

Adult↗
PubMed1999

The radiological exposure of man from radioactivity in the Baltic Sea.

A radiological assessment has been carried out considering discharges of radioactivity to the Baltic Sea marine environment since 1950. The sources of radioactivity that have been evaluated are atmospheric nuclear-weapons fallout, fallout from the Chernobyl accident in 1986, discharges of radionuclides from Sellafield and La Hague transported into the Baltic Sea, and discharges of radionuclides from nuclear installations located in the Baltic Sea area. Dose rates from man-made radioactivity to individual members of the public (critical groups) have been calculated based on annual intake of seafood and beach occupancy time. The dose rates to individuals from the regions of the Bothnian Sea and Gulf of Finland are predicted to be larger than from any other area in the Baltic Sea due to the pattern of Chernobyl fallout. The dose rates are predicted to have peaked in 1986 at a value of 0.2 mSv year-1. Collective committed doses to members of the public have been calculated based on fishery statistics and predicted concentrations of radionuclides in biota and coastal sediments. The total collective dose from man-made radioactivity in the Baltic Sea is estimated at 2600 manSv, of which approximately two-thirds originate from Chernobyl fallout, approximately one-quarter from atmospheric nuclear-weapons fallout, approximately 8% from European reprocessing facilities, and approximately 0.04% from nuclear installations bordering the Baltic Sea area. An assessment of small-scale dumping of low-level radioactive waste in the Baltic Sea in the 1960s by Sweden and the Soviet Union has showed that doses to man from these activities are negligible. Dose rates and doses from natural radioactivity dominate except for the year 1986 where dose rates to individuals from Chernobyl fallout in some regions of the Baltic Sea approached those from natural radioactivity.

Baltic States↗