Biomedical subjects

H J Wagner

Publications and source records attributed to H J Wagner.

At least 73 records · Page 4Linked to original sources

PubMed1998

The eyes of deep-sea fish. II. Functional morphology of the retina.

Three different aspects of the morphological organisation of deep-sea fish retinae are reviewed: First, questions of general cell biological relevance are addressed with respect to the development and proliferation patterns of photoreceptors, and problems associated with the growth of multibank retinae, and with outer segment renewal are discussed in situations where there is no direct contact between the retinal pigment epithelium and the tips of rod outer segments. The second part deals with the neural portion of the deep-sea fish retina. Cell densities are greatly reduced, yet neurohistochemistry demonstrates that all major neurotransmitters and neuropeptides found in other vertebrate retinae are also present in deep-sea fish. Quantitatively, convergence rates in unspecialised parts of the retina are similar to those in nocturnal mammals. The differentiation of horizontal cells makes it unlikely that species with more than a single visual pigment are capable of colour vision. In the third part, the diversity of deep-sea fish retinae is highlighted. Based on the topography of ganglion cells, species are identified with areae or foveae located in various parts of the retina, giving them a greatly improved spatial resolving power in specific parts of their visual fields. The highest degree of specialisation is found in tubular eyes. This is demonstrated in a case study of the scopelarchid retina, where as many as seven regions with different degrees of differentiation can be distinguished, ranging from an area giganto cellularis, regions with grouped rods to retinal diverticulum.

Animals↗

PubMed1998

[Infrapopliteal angioplasty: a forgotten region?].

Although percutaneous transluminal angioplasty (PTA) has become established as an endovascular technique--in the more strict sense as a balloon dilatation but being increasingly supplemented by stent implantations--for many vascular regions, reports on infrapopliteal angioplasties are rather scarce. With the development of hydrophilically coated guide wires, improved catheter materials, and dedicated balloon catheters for infrapopliteal use, dilatation treatments distal of the popliteal artery are now standard procedures. Major advances in peri-interventional drug management have also made their contribution. The initial technical and clinical results obtained are excellent. For the majority of the patients, the main concern is for limb salvage. In this context, infrapopliteal PTA also achieves satisfactory results. However, the long-term results must still be considered as unsatisfactory since recurrences are frequent and require repeat interventions. Therefore new therapeutic strategies are required that can reduce re-stenoses especially in this peripheral vascular segment.

Angioplasty, Balloon↗

PubMed1998

[Bacteremia in intra-arterial angiography, percutaneous transluminal angioplasty and percutaneous transhepatic cholangio-drainage].

PURPOSE: Prospective evaluation of the rate of bacteremia attributed to invasive radiological techniques. METHODS: Aerobic and anerobic blood cultures were obtained in 100 patients (62 men, 38 women; mean age 65 +/- 14 years) undergoing intra-arterial angiography (N = 50), PTA (N = 30) or percutaneous transhepatic biliary drainage (PTCD; N = 20). Samples were taken before the treatment (T0), immediately after puncture of the vessel or bile duct (T2), and 30 min after the termination of the procedure (T3). RESULTS: The overall rate of bacteremia was 18%. During diagnostic angiography a 16% rate of temporary bacteremia (no positive T3 samples) was observed. During PTA the rate was 27% (no clinically significant infectious disease) and during PTCD the rate was 10% (5% cholangitis with septicemia). We isolated staphylococci (S. epidermidis: N = 7, S. species: N = 3, S. aureus: N = 1), streptococci (N = 2), Propionibacterium acnes (N = 5), E. coli (N = 1), Enterococcus faecium (N = 1), Enterobacter species (N = 1), and Clostridium perfringens (N = 1). Apart from the one patient with cholangitis no clinical infectious complication occurred. CONCLUSION: Temporary bacteremia is rather frequent during invasive radiological procedures. Strictly aseptic conditions and antibiotic prophylaxis, specially in case of implantation of a permanent foreign body, is warranted.

Aged↗

PubMed1998

[Mortality and morbidity conference in radiology].

PURPOSE: To establish a morbidity and mortality conference in a radiology department as an instrument of quality assurance. METHODS: Since April 1995 a monthly conference is held in the radiology department. Complications of invasive diagnostic procedures (angiography and biopsy) and minimal invasive interventions are presented. Cases of morbidity (major complications) and mortality (deceased patients, who were examined or treated in the radiology department before) are discussed. The identification of cases was possible due to a data base that included all such procedures prospectively. RESULTS: Twenty cases of major complications were identified and discussed during 18 morbidity and mortality conferences in 1996 and 1997. Out of the 9 patients who died in our hospital and previously had an interventional procedure in the radiology department, one case was identified as being procedure-related. An analysis of this case was performed. CONCLUSION: With a formalised structure of case detection, the morbidity and mortality conference becomes a tool of a complete analysis of complications and a meaningful instrument for the solution of problems concerning procedure-related complications.

Aged↗

PubMed1998

A craniospinal enterogenous cyst: case report.

An enterogenous cyst of the craniospinal region producing medullary compression is reported in a 4.5-year-old boy. The patient presented with stiffness of the neck and headache, but otherwise without neurological deficits. Magnetic resonance imaging (MRI) demonstrated a high-intensity mass extending from the cerebellomedullary cisterna to the second cervical vertebra flattening the medulla and the upper cervical cord. Complete recovery ensued following total excision of the cyst. Histologically, the cyst was lined by a single layer of PAS-positive columnar epithelium. Presentation of this unusual case is discussed together with a review of the literature.

Child, Preschool↗

PubMed1998

K-ras oncogene mutations indicate malignancy in cystic tumors of the pancreas.

OBJECTIVE: To evaluate clinical parameters, presurgical diagnostic tests, histologic findings, and the presence of K-ras oncogene mutations in cystic tumors of the pancreas to determine which best predict malignancy. SUMMARY BACKGROUND DATA: Because presurgical, intraoperative, and final pathologic differentiation is difficult in cystic tumors of the pancreas, it would be a major benefit to identify markers that accurately predict malignancy in these rare tumors. The role of K-ras oncogene mutations as an indicator of malignancy has not been determined in these tumors. METHODS: Nineteen patients with cystic tumors of the pancreas were evaluated, including K-ras mutation analysis based on polymerase chain reaction and restriction digestion assays and direct DNA sequencing, to screen for parameters that accurately predict malignancy. RESULTS: All malignant cystic pancreatic tumors (five cystadenocarcinomas and three mucin-producing adenocarcinomas) harbored K-ras mutations at codon 12 or 13. K-ras mutations were also detected in the percutaneous fine-needle aspirates of two of these patients. In contrast, none of nine benign cystadenomas or the solid-papillary neoplasm had K-ras mutations. None of the patients with a benign tumor carrying K-ras wild-type sequences developed recurrent disease after a mean follow-up of 50 months. Seven of the 8 malignant cystic pancreatic tumors, but none of the 11 benign tumors, showed dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography. CONCLUSIONS: K-ras mutation analysis seems to be a powerful tool to determine the malignant potential of cystic pancreatic tumors before and after surgery. Dilatation of the main pancreatic duct on computed tomography or endoscopic retrograde cholangiopancreatography is highly suggestive for malignancy in these rare tumors.

Adult↗

PubMed1998

Correlation of flow velocity measurements by magnetic resonance phase contrast imaging and intravascular Doppler ultrasound.

RATIONALE AND OBJECTIVES: The authors compare the magnetic resonance (MR) phase contrast flow velocity measurements in varying concentric stenoses with invasive measurements obtained with a Doppler guidewire. METHODS: Flow velocity measurements were obtained using a calibrated 0.018 inch 12 MHz Doppler guidewire and a 1.0 T MR imaging system in a pulsatile hydraulic model with variable arterial stenoses. Velocity measurements were performed proximal, intrastenotic, and distal to the stenoses. The cross-sectional area of stenosis was calculated from the data of both methods. For MR imaging measurements, fast low-angle shot two-dimensional phase contrast sequences with different velocity encodings were used. RESULTS: Phase contrast flow measurements correlated well (r = 0.95, Pearson) with Doppler guidewire-based flow velocity data. Generally, flow velocities obtained with MR imaging were lower when compared with the Doppler-based data (P < or = 0.001, Wilcoxon matched pairs test). However, the ratios and the calculated cross-sectional area of stenoses showed a high correlation (r = 0.96) with the predefined area of stenoses. CONCLUSIONS: The assessment of flow alterations in vitro due to variable stenoses using MR phase contrast flow measurements is very well correlated with the Doppler guidewire. Consequently, these results required in vivo measurements of atherosclerotic lesions to evaluate the clinical impact.

Blood Flow Velocity↗

PubMed1997

Connectivity patterns of cone horizontal cells in blue acara (Aequidens pulcher, Cichlidae) reared in different light regimes.

Two types of cone horizontal cells were identified morphologically in the retina of a trichromatic fish by fluorescent labelling with Lucifer Yellow and confocal laser scanning microscopy. H1 cells are located adjacent to the outer plexiform layer, have large somata, small dendritic fields, and contact all cone types. H2 cells are positioned vitread to the H1 cells, have small somata, and large dendritic fields. Their dendrites invaginate the synaptic pedicles of short wavelength sensitive single cones and show a significant preference for one of the spectrally different members of the double cones, presumably the middle wavelength sensitive member. We tested the impacts of different visual environments on the development of these connectivity patterns and found minor changes induced by rearing in white light of different intensities or monochromatic blue light.

Adaptation, Physiological↗

PubMed1997

[Combined intraoperative retrograde stent implantation and thrombendarterectomy of the carotid artery].

HISTORY AND CLINICAL FINDINGS: A 63-year-old man developed recurrent transitory ischaemic episodes of vertigo and weakness in the legs 6 weeks before admission. 3 weeks later he had a left amaurosis fugax. A stenotic murmur was heard over the left carotid artery. INVESTIGATION: Intraarterial digital subtraction angiography of the arteries to the head revealed occlusion of the right internal carotid artery (RICA) and marked narrowing at the origin of the left common carotid artery (LCCA), which could not be passed by catheter. TREATMENT AND COURSE: As a catheter could not be passed into the LCCA, a stent was at operation placed retrogradely into it. Intraoperative angiography showed subtotal stenosis of the left ICA, which was treated by thrombendarterectomy and dacron patch-plasty. The postoperative course was without complication and the patient was free of symptoms. Follow-up angiography was unremarkable. CONCLUSION: If a stenosis of the carotid artery cannot be passed by catheter, intraoperative retrograde placement of a stent is an alternative to percutaneous antegrade transluminal angioplasty or surgical bypass.

Carotid Artery, Internal↗

PubMed1997

Density ratio of dopaminergic versus serotonergic cells correlates with cone-to-rod ratio in teleost retinas.

Dopaminergic and serotonergic cells were visualised immunohistochemically with antibodies against tyrosine hydroxylase and serotonin in retinal wholemounts of eight teleosts from different habitats and with different rod-to-cone ratios. The cell densities were calculated, and the density ratio of dopaminergic cells versus serotonergic cells was compared among these fish species. The density ratio was high (1.9-2.7) in three out of the four species of cichlid fish studied with cone densities roughly equalling rod densities, medium in roach (0.8) where rods dominate cone numbers, and low in deep-sea fish (0.2-0.4) with pure rod retinas. These observations confirm earlier findings on the species-specificity of the ratio of dopaminergic versus serotonergic cells in the retina and further demonstrate a close correlation between the rod-to-cone ratio, and the density ratio of dopaminergic versus serotonergic cells in the inner retina. The possible significance for the processing of photopic and scotopic information in the inner retina is discussed.

Animals↗

PubMed1997

Lytic replication of Epstein-Barr virus in the peripheral blood: analysis of viral gene expression in B lymphocytes during infectious mononucleosis and in the normal carrier state.

Epstein-Barr virus (EBV) has been shown to establish latency in resting B lymphocytes of the peripheral blood. This creates a virus reservoir in contrast to lytic virus replication, which is thought to be restricted to differentiated epithelial cells in vivo. So far, the route of transmission between B cells and the production of progeny virus in the epithelial tissue has remained unclear. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry analysis of 16 patients with acute infectious mononucleosis (IM) and 25 healthy seropositive donors was performed to detect lytic replication gene products in B lymphocytes of the peripheral blood. Transcriptional activity was found in peripheral blood B lymphocytes (PBLs) for BZLF1 in 88%, BALF2 in 50%, and BcLF1 in 25% of the tested IM patients. All positive results were further confirmed in enriched B-cell populations by antigen determination using immunostaining with the APAAP technique. Furthermore, we detected transcripts for BZLF1 in 72% and for BALF2 in 16% of peripheral B lymphocytes of healthy seropositive donors. In contrast to patients with IM, no signals for BcLF1 were ever found in healthy seropositive donors. In these individuals, lytic replication of EBV is probably restricted by immunologic and gene regulatory mechanisms, whereas in the absence of immunologic control, reflected here by IM patients, the production of infectious virus becomes visible in PBLs.

B-Lymphocytes↗

PubMed1997

Presynaptic bodies ("ribbons"): from ultrastructural observations to molecular perspectives.

The morphological diversity and dynamic aspects of presynaptic bodies are summarised. Molecular characteristics of the presynaptic machinery are discussed and the signals that control the plasticity of the presynaptic bodies are examined. A review is presented of recent findings regarding the physiology of tonically active synapses. The significance of the synaptic bodies and their dynamic changes in retinal and pineal photoreceptors are considered.

Animals↗

PubMed1997

[Must the patient fast before intravascular injection of a non-ionic contrast medium? Results of a controlled study].

PURPOSE: Prospective evaluation of food and fluid restriction before the intravascular injection of a non-ionic contrast medium. MATERIAL AND METHODS: 1000 patients (657 men, 343 women; average age 59 +/- 1/4 5 years) undergoing intravascular contrast injections (CT, phlebography, angiography, urography) were randomly allocated to two groups. Group A had no fluid or solids for at least four hours before the injection (499 cases); group B were allowed unlimited food and fluid (501 cases). Both groups were comparable in all other respects and all were given the non-ionic contrast medium iopamidol (300 mg l/ml). RESULTS: The incidence of acute complications was 3.5%. There was, however, no statistically significant difference between the two groups (p = 0.29). Late adverse reactions were seen in 3.9% patients. There was again no difference between the two groups (p = 0.33). No serious or life threatening complications occurred. CONCLUSION: Restriction of food and fluid before intravascular injection of contrast medium does not reduce the number of adverse side effects. For reasons of patient comfort and compliance, and to achieve adequate hydration, the patient should not fast before injection of contrast.

Adult↗

PubMed1997

[In vitro evaluation of the intravasal Doppler guide wire: determination of hemodynamic effects of stenoses in a flow model].

PURPOSE: In a pulsatile hydraulic model, haemodynamic changes caused by stenoses were assessed using an intravascular Doppler guide wire. MATERIAL AND METHODS: In defined stenoses (25, 50, 75 and 87.5% diameter ratio), and with and without collateral flow, a 0.018 inch (0.46 mm) 12 MHz Doppler guide wire was assessed. Flow velocity measurements were taken 20 mm proximal, in, and 20 mm distal to the stenoses. Average peak velocity (APV) and ratios of pre-/poststenotic velocities and pre-/intrastenotic velocities of APV were compared with the grade of stenosis. The degree of the stenosis calculated by the ratio of the cross-sectional area, using the pre- and intrastenotic APV, was correlated with the actual stenosis. RESULTS: The intrastenotic APV increased significantly (APV proximal to the stenosis 15.15 +/- 4.5 cm/s, intrastenotic APV 134.8 +/- 130.9, p < 0.01, Wilcoxon-Mann-Whitney test). The difference between APV pre- and poststenotic was not significant (p > 0.5). Concerning the grade of stenosis the ratio APV pre-/intrastenotic and the consecutively calculated cross-sectional area stenoses was the best predictor (correlation with the known cross-sectional area stenosis r = 0.94 Pearson). CONCLUSION: Using the Doppler guide wire, APV measurements pre- and intrastenotic enable a reliable quantification of the grade of stenosis. The stenosis calculated via the cross-sectional area correlates significantly with the actual stenosis.

Arterial Occlusive Diseases↗

PubMed1997

Rapid thrombectomy with a hydrodynamic catheter: results from a prospective, multicenter trial.

PURPOSE: To evaluate efficacy and safety of a hydrodynamic rheolytic thrombectomy device for rapid percutaneous treatment of acute thromboembolic occlusions of native lower-extremity arteries and bypass grafts. MATERIALS AND METHODS: In 50 patients, thrombectomy was performed with the rheolytic catheter at four centers. Patients had acute occlusions of native lower-extremity arteries (n = 39) or acute thrombosis of lower-limb bypass grafts (n = 11). Estimated occlusion age was 5 days +/- 5. Mean thrombus length was 15 cm +/- 11. Clinical success was measured on a scale of -3 (deterioration) to +3 (improvement) with established criteria. RESULTS: With the thrombectomy catheter, the majority of thrombus material was removed and antegrade blood flow was reestablished in 45 (90%) patients. Technical success (residual luminal narrowing < 50%) was 52% with use of the device alone. Adjunctive therapy was performed in 45 patients. Clinical improvement after intervention was +3 in 25 (50%) patients, +2 in 10 (20%), +1 in six (12%), and 0 (no improvement) in nine (18%). Clinically unimportant complications related to use of the device were one (2%) distal embolization and two (4%) dissections. Laboratory analysis revealed hemolysis without clinical sequelae. Primary patency rates were 76% after 30 days, 74% after 3 months, and 69% after 1 year. CONCLUSION: The hydrodynamic catheter appears to be safe and effective for rapid thrombectomy.

Aged↗

PubMed1996

Effect of astroglial cell swelling on pH of acidic intracellular compartments.

A variety of pathological conditions lead to swelling of astrocytes, which in turn stimulates ion release by activation of ion channels at the plasma membrane. In the present study, acridine orange and fluorescein isothiocyanate coupled to dextran (FITC-dextran) have been used to examine the effect of cell swelling on pH in acidic compartments of cultured astroglial cells. Both NH4Cl (2 mM) and chloroquine (10 microM), known to alkalinize acidic cellular compartments, led to the expected increase in acridine orange fluorescence intensity. Similar, albeit smaller, effects were elicited by a reduction of extracellular osmolarity (-80 mOsm) and treatment of the cells with glutamate (l mM), manoeuvres which enhanced cell volume. Determination of changes in the FITC-dextran fluorescence ratio (485/440 nm) allowed quantification of the pH changes in lysosomal compartments. Treatment with NH4Cl, reduced extracellular osmolarity and glutamate increased lysosomal pH by 0.65 +/- 0.07, 0.85 +/- 0.14 and 0.25 +/- 0.07, respectively. Measurement of cytosolic pH using 2',7',-bis-(2-carboxyethyl)-5- (and -6) carboxyfluorescein (BCECF) demonstrated a pronounced acidification following cell swelling, observed with both reduced extracellular osmolarity (by 0.23 +/- 0.05 pH units) and 1 mM glutamate (by 0.26 +/- 0.02 pH units). In conclusion, pH within lysosomes and possibly other acidic cellular compartments of astrocytes is increased by cell swelling, which may have important consequences for astrocyte function.

Acridine Orange↗

PubMed1996

The eye of the blue acara (Aequidens pulcher, Cichlidae) grows to compensate for defocus due to chromatic aberration.

By rearing fish in various monochromatic illuminations we investigated (1) the potential for compensation of refractive error due to chromatic aberration, (2) the contributions of the chromatic channels to emmetropization, and (3) the role of color cues in the control of eye growth. Cichlid fish (Aequidens pulcher) were reared for 6 months (12 h light/12 h dark) in monochromatic lights (623.5, 534.1, 485.0 nm; spectral purity 5-10 nm). Light levels were isoirradiant at 1.1.10(12) quanta/s/cm2. Two control groups were reared in white light with down-welling illuminances of 0.2 and 33 lx. Nasotemporal diameters (NTDs) of the eyes were measured in relation to lens size. Due to the oblique axis of highest acuity vision in cichlids, NTD is considered to be a more important dimension than axial length. Variances in NTD were equally small in all rearing groups. NTDs were enlarged with increasing wavelengths of the rearing lights with highly significant values over controls in the red-light group. The wavelength-dependent size of the eyes matched the changes in focal length due to longitudinal chromatic aberration. Complete recovery from eye enlargement was observed after fish reared in red light were exposed to a white light regime for 5 weeks. Small variances in NTD in all groups indicated stringent control of eye growth in the absence of color cues. The reversibility of the increase in NTD in fish reared in red light suggests that the eyes were emmetropized by visually guided mechanisms. Eye size in fish reared in white light was intermediate between the values expected if only blue-sensitive single or the red- and green-sensitive double cones contributed to the control of eye growth. This suggests that all chromatic channels participate in emmetropizing the fish eye.

Adaptation, Ocular↗

PubMed1996

Control of rod retinomotor movements in teleost retinae: the role of dopamine in mediating light-dependent and circadian signals.

In the retinae of lower vertebrates, several morphological changes, including photomechanical movements of rods, cones and pigment epithelium, occur during light and dark adaptation. We studied the contribution of exogenous and endogenous circadian control mechanisms to rod retinomotor movements in the teleost retina and their dependence on an intact dopaminergic system. Blue acara (Aequidens pulcher) were kept under a 12:12 h light/dark cycle. One population of fish remained untreated; another population was treated with 6-hydroxy-dopamine, selectively to destroy dopaminergic cells. Rod positions were determined in semi-thin radial sections. During the normal light/dark cycle, rods were elongated during the day and contracted at night. Rod retinomotor movements persisted during two cycles of continuous darkness. Expected light levels of rod positions were reduced by about 40% in comparison with normal light phases. Adaptation-dependent retinomotor movements and movements driven by an endogenous circadian clock also occurred in dopamine-depleted retinae. No statistically significant differences were observed between dopamine-containing and dopamine-depleted retinae. We conclude that rod retinomotor movements in teleost retinae are controlled by light and by an endogenous circadian clock. Dopamine plays no essential role in the light-dependent and endogenous control of rod retinomotor movements.

Animals↗