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Biomedical subjects

T Wagner

Publications and source records attributed to T Wagner.

At least 109 records · Page 6Linked to original sources
PubMed1999

High-precision assessment of interface lattice offset by quantitative HRTEM.

We introduce a new method to determine the 'lattice offset' or 'rigid-body shift' between two crystals forming an interface. Our method relies on quantitative evaluation of high-resolution transmission electron microscopy images. Employing the (001)-orientated interface between Al and MgAl2O4 in parallel orientation as a model system we demonstrate that we can assess the interface lattice offset with a precision in the picometre range.

Journal Article↗
PubMed1999

Direct versus iterative structure retrieval for a Cu/Ti misfit dislocation: a comparison of various 1Å HREM technologies.

Using an interface between Cu/Ti as an example, two HREM-based image analysis techniques, strain mapping and iterative digital image matching, are compared. The validity limit of these techniques is discussed as a function of specimen thickness and microscope technology. Two criteria are used to assess the limits: (i) the difference between two geometric phase maps, one calculated in image plane and one in object plane, and (ii) a difference image from two HREM simulations of two structure models differing in one atomic column. The latter displays the overall delocalisation of information by the microscope due to diffraction and imaging. It is outlined how far images and strain maps, obtained for high-voltage microscopy at 1250 kV and CS correction at 200 kV, are identical. Both techniques exhibit a significantly increased regime of applicability of strain mapping near defect cores. Simulations for a 400 kV HREM and a 300 kV FEGTEM with and without focal series reconstruction complement the study.

Journal Article↗
PubMed1999

The sentinel lymph node concept in prostate cancer - first results of gamma probe-guided sentinel lymph node identification.

OBJECTIVE: The goal of this study was to show lymphatic drainage and to verify the validity of lymphoscintigraphy for the identification of the sentinel lymph node (SLN) in prostate cancer. Furthermore, the question is to be raised whether the standardized pelvic lymphadenectomy is a sufficient means for also detecting solitary micrometastases. PATIENTS AND METHODS: Eleven patients with prostate cancer received a sonographically controlled, transrectal administration of a technetium-99m colloid injected directly into the prostate 1 day prior to pelvic lymphadenectomy. 20 min later the dynamic lymphoscintigraphy was carried out. During surgery, the SLNs were identified by using a gamma probe. The standard pelvic lymphadenectomy was performed after removal of the SLN. RESULTS: In 3 of 4 patients with micrometastasis the spread of the tumor could exclusively be found in those nodes which had been identified as SLNs by means of scintigraphy by combining preoperative lymphoscintigraphy and intraoperative gamma probe detection. In 2 cases, the pathologically proved SLNs were situated at the anteromedial region of the internal iliac artery, thus being located outside of the standard pelvic lymphadenectomy area. In 1 patient, however, the micrometastasis was found beyond those nodes which had been identified as SLN intraoperatively. CONCLUSIONS: In the future, we expect the restriction of pelvic staging lymphadenectomy to scintigraphically proved SLN. The perioperative morbidity may be reduced by increasing the sensitivity of the detection of micrometastases. Our data confirm earlier perceptions, according to which even modified standardized pelvic lymphadenectomy is considered insufficient in terms of the detection of micrometastases.

Aged↗
PubMed1998

[Subcutaneous manifestations of a centrocytic non-Hodgkin lymphoma at the injection site of a mistletoe preparation].

HISTORY AND CLINICAL FINDINGS: A 73-year-old man, first diagnosed as having centrocytic Non-Hodgkin lymphoma 5 years previously, presented with subcutaneous nodes of the abdominal wall at precisely the sites of previous regular injections of a mistletoe preparation. These nodes had first appeared 5 weeks after the first injection. Injections were stopped and he reported to the out-patient clinic. Except for the visible and easily nodes in the anterior wall no other subcutaneous nodes were palpated. Prominent cervical lymphomas and swelling of the epicranial aponeurosis and lower lip had, according to the patient, been present for some time. INVESTIGATIONS: There was a T-lymphocytopenia, lactate dehydrogenase activity was raised to 255 U/l. The subcutaneous nodes in the anterior abdominal wall were also demonstrated by ultrasound. Computed tomography showed them as having the density of connective tissue and being up to 5 cm in diameter. The excised nodes histologically revealed to be infiltrations by the centrocytic lymphoma. TREATMENT AND COURSE: Once the mistletoe injections had been discontinued no further subcutaneous infiltrates were seen despite the progression of the lymphoma. Six weeks later the patient died of bilateral pneumonia. CONCLUSION: There are pointers that high concentrations of mistletoe preparations subcutaneously injected can have a growth-promoting action on cells of a centrocytic lymphoma. As part of a leukaemic "wash-out", these cells reach the subcutaneous tissue. This proliferative stimulus may have been mediated by a high local concentration of interleukin-6 liberated from the skin by mistletoe lectins.

Abdominal Muscles↗
PubMed1998

Right auditory cortex lesion in Mongolian gerbils impairs discrimination of rising and falling frequency-modulated tones.

Mongolian gerbils (Meriones unguiculatus) were trained in a shuttle box to discriminate the direction in frequency-modulated tones (FM). Whereas control animals easily acquired FM discrimination, animals with auditory cortex lesion on the right side showed considerable difficulties in learning this task. The discrimination performance of gerbils with left auditory cortex lesion, however, was not different from controls. This study, suggesting that the right auditory cortex plays a dominant role in FM discrimination learning in gerbils, describes a useful animal model for investigation of the basic mechanisms underlying hemispheric asymmetries in auditory perception.

Acoustic Stimulation↗
PubMed1998

Crystallization and preliminary X-ray diffraction studies of E. coli porphobilinogen synthase and its heavy-atom derivatives.

Porphobilinogen synthase (PBGS) catalyzes the condensation of two identical substrate molecules, 5-aminolevulinic acid (ALA), in an asymmetric manner to form porphobilinogen. E. coli PBGS is an homooctameric enzyme. The number of active sites is not clear, but each subunit binds one ZnII ion and one MgII ion. Diffraction-quality crystals of native E. coli PBGS have been obtained, and unit-cell dimensions (a = 130.8, c = 144.0 A) are reported. These crystals diffract to about 3.0 A resolution.

Crystallization↗
PubMed1998

Membrane properties of giant neurons in the caudal pontine reticular formation in vitro.

The intrinsic membrane properties of giant neurons of the caudal pontine reticular nucleus (PnC) were evaluated in a rat brain slice preparation. These neurons show low RP levels, long membrane time constants, low membrane resistance, tonic AP firing, and a lack of rectification behavior. The results are compared to those measured in adjacent areas of the reticular formation and discussed for their impact on triggering and modulating the acoustic startle response.

Animals↗
PubMed1998

[Surgical treatment of acute pericardial tamponade in an infestation of the heart by Echinococcus].

HISTORY AND CLINICAL FINDINGS: A 56-year-old turkish patient, previously in good health, was admitted because of pain suggesting myocardial infarction. Physical examination of the heart, lungs and abdomen was unremarkable. INVESTIGATIONS AND DIAGNOSIS: The concentrations of myocardium-specific enzymes were not elevated and the ECG showed no signs of ischaemia. Echocardiography and magnetic resonance imaging ruled out acute aortic dissection, but demonstrated a round cystic space-occupying mass over the anterior wall of the heart. Hydatid cyst was suspected from the imaging results and the patient's origin from area endemic for Echinococcus. The diagnosis was confirmed by a titre of 1:6,400 (normal: 1: < 100) for Echinococcus antibodies. TREATMENT AND COURSE: Albendazole administration was initiated. Planned elective surgical removal of the hysatid cyst had to be performed urgently because of acute pericardial tamponade. Cyst rupture was suspected but an actually undamaged cyst was subtotally removed under cardiopulmonary bypass. The postoperative course was uneventful and albendazole treatment was continued. CONCLUSION: Because of the high incidence of fatal complications urgent surgical removal under cardiopulmonary bypass is the treatment of choice for hydatid cyst involving the heart. Perioperative albendazole administration is also essential.

Acute Disease↗
PubMed1998

[Primary hemangiosarcoma of the heart].

Primary cardiac sarcomas are malignant neoplasmas of mesenchymal cells. Angiosarcomas, unlike all other primary cardiac sarcomas, are typically found in the right atrium. We present the case of a 52-year-old patient in whom through echocardiography, computed tomography and angiography the precise diagnosis and extent of the tumor was revealed. Surgical treatment consisted of excision of the tumor with right atrium patch-plasty under cardiopulmonary bypass. Despite the successful operation the patient died 6 months later because of metastasis. Very early and precise diagnosis is essential to improve patient survival and prevent the development of metastases.

Blood Vessel Prosthesis Implantation↗
PubMed1998

[Clinical, anatomical-pathological and therapeutic correlates of benign intracavitary heart tumors].

Benign intracavitary cardiac tumors lead to "malignant" complications, so early diagnosis and adequate treatment are of vital importance. Our investigation summarizes a 10-year experience after surgical treatment of 29 patients suffering from benign intracavitary cardiac tumors. The postoperative histological examination revealed a myxoma in 27 cases; in 2 cases a papillary fibroelastoma was diagnosed. The main symptom in 19 patients was dyspnea. In 8 cases an embolic event occurred. All patients underwent extirpation of the tumor. Early mortality was 10%, while late mortality was 4%. The treatment of choice of benign intracavitary cardiac tumors is extirpation, which, due to unpredictable embolic complications, is to be carried out immediately should the tumor have a lobulated tuberous surface. In such cases the descriptive function of echocardiography is of considerable importance.

Adult↗
PubMed1998

A genetic screen for elements of the network that regulates neurogenesis in Drosophila.

The development of external sensory organs on the notum of Drosophila is promoted by the proneural genes achaete and scute. Their activity defines proneural cell clusters in the wing imaginal disc. Ectopic expression, under control of the GAL4 system, of the proneural gene lethal of scute (l'sc) causes the development of ectopic bristles. Persistent ectopic expression of l'sc is not sufficient to impose a neural fate on any given cell. This implies that mutual inhibition, mediated by the Notch signaling pathway, occurs among the cells of the ectopic proneural cluster. Consequently, the dominant, quantifiable phenotype associated with ectopic expression of l'sc is modified by mutations in genes known to be involved in neurogenesis. This phenotype has been utilized to screen for dominant enhancers and suppressors that modify the number of ectopic bristles. In this way, about 100,000 progeny of EMS or X-ray-treated flies have been analyzed to identify autosomal genes involved in regulation of the neural fate. In addition 1200 chromosomes carrying lethal P-element insertions were screened for modifiers. Besides mutations in genes expected to modify the phenotype, we have isolated mutations in six genes not known so far to be involved in neurogenesis.

Alleles↗
PubMed1998

Fibrinolysis-adjusted perioperative low-dose aprotinin reduces blood loss in bypass operations.

BACKGROUND: Postoperative bleeding still remains a serious problem in bypass surgery. This study evaluated fibrinolysis and perioperative low-dose antifibrinolytic regimens adjusted to the time course of fibrinolysis. METHODS: In a prospective, randomized study of 42 patients undergoing bypass grafting, patients received low-dose aprotinin (group A; n = 14) or low-dose tranexamic acid (group TA; n = 14) intraoperatively and postoperatively, respectively, with no antifibrinolytics for comparison (group C; n = 14). Parameters of procoagulation, fibrinolysis, and activated factor VII were measured preoperatively, intraoperatively, and postoperatively. Blood loss was determined up to 24 hours. RESULTS: The level of thrombin-antithrombin III complex was significantly decreased postoperatively in the treatment groups (group A and TA versus C: 25 +/- 14 and 19 +/- 10 microg/L, respectively, versus 40 +/- 21 microg/L; p < 0.05). Levels of plasmin-antiplasmin complexes were significantly decreased postoperatively in group A (607 +/- 231 microg/L) versus group C (825 +/- 225 microg/L) (p < 0.05) but were increased in group TA (1,145 +/- 394 microg/L) versus group C (p < 0.05). At all times intraoperatively and postoperatively, levels of D-dimers were significantly decreased in group A and group TA versus control (p < 0.001), indicating that fibrinolysis persists after the operation. Intraoperatively, the factor VIIa level decreased significantly in group A (20 +/- 8 mU/mL) versus group C (31 +/- 15 mU/mL) (p < 0.05), but not in group TA (32 +/- 15 mU/mL). Blood loss was significantly lower in group A (135 +/- 37 mL) and group TA (155 +/- 71 mL) versus group C (354 +/- 170 mL) (p < 0.001). CONCLUSIONS: This low-dose aprotinin regimen adjusted to perioperative fibrinolysis reduces blood loss significantly in coronary bypass grafting. For further progress in this subject, clinical investigations of individual fibrinolysis-adjusted antifibrinolytic treatment seems warranted.

Aged↗
PubMed1998

Categorical discrimination of direction in frequency-modulated tones by Mongolian gerbils.

Discrimination of the direction of linearly frequency-modulated tones (FMs) was investigated in adult Mongolian gerbils (Meriones unguiculatus) using a footshock motivated shuttle box avoidance go/no go procedure. Symmetric pairs of FMs with frequency linearly increasing with time (ascending FMs) and with frequency linearly decreasing with time (descending FMs) were used as conditioned stimuli, CS+ and CS-, respectively. Stimuli were presented in randomized order in daily sessions over a period of several months. After a number of sessions, the set of conditioned stimuli was changed with respect to frequency range, steepness of modulation and duration. In experiment 1, we observed that gerbils could discriminate between the ascending 2-4 kHz CS+ and the descending 4-2 kHz CS- after a training period of 10-15 days. In experiment 2, we used FM pairs of six other frequency ranges in successive sessions (6-13; 1-2; 13-25; 0.5-1; 3 6; 0.25 0.5 kHz). We found that in the final session the last FM pair (0.25-0.5 kHz) was discriminated already after 3-4 days. Experiment 3 showed that the animals were able to discriminate five of the FM pairs learned in the separate sessions of experiment 2 (i.e. 10 different stimuli) when they were given in randomized order during one training session. In experiment 4, novel FM pairs (not heard before) and familiar FM pairs (trained in experiments 1-3) were presented within one session. It was found that, except for FMs of very short duration and small frequency range, novel FMs were discriminated according to their modulation direction. These results show that Mongolian gerbils are able to discriminate FM tones by modulation direction and, after familiarization with a number of different FM pairs, transfer the ascending-descending concept to stimuli not heard before.

Acoustic Stimulation↗
PubMed1998

Total body irradiation and cyclophosphamide is a conditioning regimen for unrelated bone marrow transplantation in a patient with chronic myelogenous leukemia and renal failure on hemodialysis.

Five years after the diagnosis of Ph chromosome-positive chronic myeloid leukemia (CML) a 31-year-old patient developed malignant nephrosclerosis with renal failure. He then underwent an allogeneic unrelated BMT in first chronic phase CML. The preparative regimen consisted of fractionated total body irradiation (TBI) and cyclophosphamide (CY). We studied the pharmacokinetics of cyclophosphamide on hemodialysis and compared clinical parameters including time to engraftment and toxicity with parameters of a patient with normal renal function who also received an unrelated marrow as treatment for CML in first chronic phase. Our results suggest that TBI/CY is a suitable conditioning regimen for allogeneic transplantation in patients with hematological malignancy and renal failure on hemodialysis.

Adult↗
PubMed1998

Evaluation of two new integrated adapters for blood drawing in closed blood bag systems: influence on different molecular coagulation markers.

We compared a conventional blood donation bag system (A) with two newly developed ones (B, C) with integrated Y-shaped adapters. The new systems facilitate the withdrawal of blood samples in a closed system under aseptic conditions. The purpose of the study was to determine whether disturbances during blood donation in the different tubings influence the quality of the donated plasma due to activation processes of the coagulation system. In all bag samples from 34 probands for each system, we found higher levels of the global tests (aPTT, TT) compared to intraindividual controls. This was due to a greater amount of anticoagulant in the bag samples. An increase of procoagulant activity was demonstrated for bags A and C. Concerning the fibrinolytic system, values were reduced in all three systems compared to controls. In summary, the quality of the plasma in the three different bag devices was comparable to controls concerning factor activities measured as global tests. The activation of the coagulation system was only slightly higher in the new system B and C than in the conventional one (A). Therefore, the new closed systems are suitable for blood donation and reveal a high coagulation quality of the plasma.

Adolescent↗
PubMed1998

A questionnaire-based outcome analysis of the Stamey bladder neck suspension procedure for the treatment of urinary stress incontinence: the Hannover experience.

OBJECTIVES: To evaluate the long-term continence rate, including subjective satisfaction and therapy-associated morbidity, of patients undergoing Stamey bladder neck suspension. PATIENTS AND METHODS: Eighty-five women (median age 55 years, range 30-85) with urinary stress incontinence treated by Stamey bladder neck suspension at our institution between 1987 and 1995 were evaluated using an anonymous questionnaire over a mean (range) follow-up of 61 (13-93) months. RESULTS: Of the 85 patients, 44 (52%) reported an improvement in clinical symptoms at the evaluation and 29 (34%) were completely continent after the Stamey procedure. However, 53 (62%) patients reported subjective satisfaction with the result, because they had a durable improvement in continence for a mean (range) of 44 (10-79) months. There was no correlation between the number of previous urogynaecological operations undergone by the patients and the success of the Stamey procedure. However, the frequency of complications other than urinary retention was significant during and after surgery, at 27%, and in accord with the complication rate reported in earlier studies. CONCLUSIONS: Compared with other bladder neck suspension procedures, e.g. Burch colposuspension, the Stamey procedure appears to be associated with a higher frequency of postoperative recurrent urinary stress incontinence. Therefore, the Stamey procedure should only be used if the patient demands a minimally invasive surgical procedure for bladder neck suspension. Although approximately equal to 60% of patients were satisfied with the durable improvement in clinical symptoms, it is appropriate to inform patients before surgery of the high recurrence rate after Stamey bladder neck suspension.

Adult↗