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Biomedical subjects

A Fuchs

Publications and source records attributed to A Fuchs.

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

Evaluation of endovascular techniques for creating a porcine femoral artery occlusion model.

PURPOSE: To determine the optimal endovascular approach to achieve long-term occlusion of large arteries, while preserving the integrity of periarterial tissue, in an animal model of ischemia. METHODS: Femoral artery occlusions were created in 16 pigs using detachable balloons, coils, or blinded stent-grafts. Feasibility, safety, primary and long-term success, and the degree of neovascularization were determined over a 6-month period by serial angiography and histological analyses. Four animals served as untreated controls. RESULTS: Overall primary success for all occlusion devices was 100%. The 6-month occlusion rate using detachable balloons or coils was 33% and 0%, respectively; however, all arteries occluded with blinded stent-grafts remained obstructed to the end of the study. There was no significant difference in capillary densities and collateralization of periarterial areas when occluded arteries were compared with nonoccluded controls in the same animal. No increase in collateralization was observed following endovascular arterial occlusion. CONCLUSIONS: Percutaneous insertion of blinded stent-grafts easily, safely, and reliably creates long-term arterial occlusion in pigs, which may make this a more appropriate model for studying the effects of angiogenic factors in vivo.

Anatomy, Cross-Sectional↗
PubMed2001

Laryngeal pyogenic granulomas do not express oestrogen or progesterone receptors.

The objective of this study was to determine the presence of oestrogen and/or progesterone receptors in laryngeal pyogenic granulomas and the impact of these receptors on recurrence of pyogenic granulomas. Twenty-two consecutive patients who underwent microlaryngoscopy and removal of pyogenic granulomas were studied retrospectively. The indications for surgery were airway compromise, failure of medical therapy and suspicion of malignancy. Twelve of these patients' granulomas were analysed for oestrogen and progesterone receptors. Charts were analysed for age, sex, location of the lesion, history of trauma, intubation or gastroesophageal reflux disease (GORD), airway symptoms and recurrence. Oestrogen/progesterone receptors were analysed following deparaffinization of specimens and immunostaining with prediluted anti-oestrogen receptor monoclonal antibody and anti-progesterone receptor monoclonal antibody. No sample expressed oestrogen or progesterone receptors. There were too few recurrences to detect if lack of these receptors played any role in determining outcome in this group. Most of the patients had a history of GORD, intubation or laryngeal surgery. There were 12 recurrences in four patients. All of the recurrences improved on prolonged courses of omeprazole. Pyogenic granulomas do not possess oestrogen or progesterone receptors and are unlikely to respond to hormonal therapy. Patients who have, or are being operated on for, laryngeal pyogenic granulomas should be placed on proton pump inhibitors to decrease the likelihood of recurrence.

Adult↗
PubMed2001

[Value of volume rendering in musculo-skeletal disorders].

Three dimensional imaging is increasingly important for evaluation of anatomic relationships and extent of disease, for treatment planning and for follow-up evaluation. The volume rendering technique allows creation of accurate 3D images that can be used for several clinical applications especially in musculo-skeletal disorders such as evaluation of tumors or fractures. This article describes the methods used for volume rendering technique and focuses on the specific aspects of volume rendering applied to musculo-skeletal applications.

Humans↗
PubMed2001

Influenza surveillance during winter 1997-1998 in Israel.

BACKGROUND: Each winter influenza activity is a major cause of morbidity and mortality both in Israel and worldwide. OBJECTIVES: To identify the influenza viruses active in Israel during the winter season and to assess the extent of influenza morbidity. METHODS: Information was collected on a population of 18,684 individuals enrolled in two community clinics in central Israel. It included the total number of visits for acute respiratory infection--including influenza and influenza-like illness (ARI/flu-like)--during a 20 week surveillance period (23 November 1997 to 27 March 1998) and the percent of influenza virus isolates in nasopharyngeal specimens from a sample of patients with ARI/flu-like collected on a weekly basis during the same period. RESULTS: A total of 5,947 visits for ARI/flu-like were recorded among 18,684 enrolled patients in two community clinics (18.1%). The progressive increase in the number of visits for ARI/flu-like reached a peak on week 2/98 with 597 visits and a rate of 31.95 visits per 1,000 population. After this, a decrease to the initial values was evident by week 12/98. Most affected patients were in the age groups 5-14 and 65 years and over, with a rate of 733.5 and 605.3 visits per 1,000 population, respectively. Influenza virus was isolated from 92 of the 426 nasopharyngeal specimens (21.6%). The most commonly detected strain was A/Sydney/5/97 (H3N2) like (77.2%). The peak rate of isolates was recorded at the beginning of January (01/98). CONCLUSIONS: A/Sydney/5/97 (H3N2) like-strain was the dominant influenza virus. Its presence did not prevent the simultaneous activity of influenza A/H1N1 virus. The dynamic of the clinical disease as expressed by the weekly visit rate for ARI/flu-like was similar to the temporal pattern of the virological findings. The extent of morbidity suggests moderate epidemic activity.

Adolescent↗
PubMed2000

BDCA-2, BDCA-3, and BDCA-4: three markers for distinct subsets of dendritic cells in human peripheral blood.

We have generated a panel of mAbs that identify three presumably novel human dendritic cell Ags: BDCA-2, BDCA-3, and BDCA-4. In blood, BDCA-2 and BDCA-4 are expressed on CD11c(-) CD123(bright) plasmacytoid dendritic cells, whereas BDCA-3 is expressed on small population of CD11c(+) CD123(-) dendritic cells. All three Ags are not detectable on a third blood dendritic cell population, which is CD1c(+) CD11c(bright) CD123(dim), or on any other cells in blood. BDCA-4 is also expressed on monocyte-derived and CD34(+) cell-derived dendritic cells. Expression of all three Ags dramatically changes once blood dendritic cells undergo in vitro maturation. BDCA-2 is completely down-regulated on plasmacytoid CD11c(-) CD123(bright) dendritic cells, expression of BDCA-3 is up-regulated on both plasmacytoid CD11c(-) CD123(bright) dendritic cells and CD1c(+) CD11c(bright) CD123(dim) dendritic cells, and expression of BDCA-4 is up-regulated on CD1c(+) CD11c(bright) CD123(dim) dendritic cells. BDCA-2 is rapidly internalized at 37 degrees C after mAb labeling. The three presumably novel Ags serve as specific markers for the respective subpopulations of blood dendritic cells in fresh blood and will be of great value for their further analysis and to evaluate their therapeutic potential.

Animals↗
PubMed2000

Functionally defined CD164 epitopes are expressed on CD34(+) cells throughout ontogeny but display distinct distribution patterns in adult hematopoietic and nonhematopoietic tissues.

Three distinct classes of epitopes on human CD164 have been identified. Two of these, recognized by the monoclonal antibodies 105A5 and 103B2/9E10, are the CD164 class I and class II functionally defined epitopes, which cooperate to regulate adhesion and proliferation of CD34(+) cell subsets. In this article, we demonstrate that these 2 CD164 epitopes are expressed on CD34(+) cells throughout ontogeny, in particular on CD34(+ )cell clusters associated with the ventral floor of the dorsal aorta in the developing embryo and on CD34(+) hematopoietic precursor cells in fetal liver, cord blood, and adult bone marrow. While higher levels of expression of these CD164 epitopes occur on the more primitive AC133(hi)CD34(hi)CD38(lo/-) cell population, they also occur on most cord blood Lin(-)CD34(lo/-)CD38(lo/- )cells, which are potential precursors for the AC133(hi)CD34(hi)CD38(lo/-) subset. In direct contrast to these common patterns of expression on hematopoietic precursor cells, notable differences in expression of the CD164 epitopes were observed in postnatal lymphoid and nonhematopoietic tissues, with the class I and class II CD164 epitopes generally exhibiting differential and often reciprocal cellular distribution patterns. This is particularly striking in the colon, where infiltrating lymphoid cells are CD164 class I-positive but class II-negative, while epithelia are weakly CD164 class II-positive. Similarly, in certain lymphoid tissues, high endothelial venules and basal and subcapsular epithelia are CD164 class II-positive, while lymphoid cells are CD164 class I-positive. It therefore seems highly likely that these CD164 class I and II epitopes will mediate reciprocal homing functions in these tissue types.

Adult↗
PubMed2000

Optimization of nonviral gene transfer of vascular smooth muscle cells in vitro and in vivo.

Gene therapy strategies for the prevention of restenosis postangioplasty are promising. Nonviral gene transfer to the arterial wall in vivo has so far been limited by poor efficiency. This study aimed to optimize transfection of primary vascular smooth muscle cells using cationic nonviral formulations based on cholesterol derivates (DC-, DAC-, DCQ-, and Sp-Chol), double-chained amphiphils (LipofectAMINE, DOTMA, DOSGA, DOSPER, and DOCSPER), or heterogeneous reagents (Superfect, Effectene, and Tfx-50). Estimation of transfection efficiencies was performed using galactosidase assays at different ratios of transfection reagent to plasmid DNA with reporter gene. Toxicity was monitored by analyzing cell metabolism. Transfer efficiency and safety were determined in a porcine restenosis model for local gene therapy using morphometry, histology, galactosidase assays, and reverse-transcriptase polymerase chain reaction. The highest in vitro transfection efficiency was achieved using the recently developed DOCSPER liposomes, with transfer rates of at least 20% in vascular smooth muscle cells. Transfer efficiency was further enhanced up to 20% by complexing with poly-L-lysine. Transfection efficiency in vivo in a porcine restenosis model was up to 15% of adventitial cells using DOCSPER versus 0.1% using LipofectAMINE. Toxicity in vivo and in vitro was lowest using DOCSPER. Increased biological effects were demonstrated following optimization of transfer conditions.

Angioplasty↗
PubMed2000

Theory of the relation between human brain activity (MEG) and hand movements.

Earlier research established that spontaneous changes in human sensorimotor coordination are accompanied by qualitative changes in the spatiotemporal dynamics of neural activity measured by multisensor electroencephalography and magnetoencephalography. More recent research has demonstrated that a robust relation exists between brain activity and the movement profile produced. In particular, brain activity has been shown to correlate strongly with movement velocity independent of movement direction and mode of coordination. Using a recently developed field theoretical model of large-scale brain activity itself based on neuroanatomical and neurophysiological constraints we show here how these experimental findings relate to the field theory and how it is possible to reconstruct the movement profile via spatial and temporal integration of the brain signal. There is a unique relation between the quantities in the theory and the experimental data, and fit between the shape of the measured and the reconstructed time series for the movement is remarkably good given that there are no free parameters.

Brain↗
PubMed2000

Spatiotemporal analysis of neuromagnetic events underlying the emergence of coordinative instabilities.

A full-head 143-channel superconducting quantum interference device was used to study changes occurring in the magnetic activity of the human brain during performance of an auditory-motor coordination task in which the rate of coordination was systematically increased. Previous research using the same task paradigm demonstrated that spontaneous switches in timing behavior that arise with higher coordination rates are accompanied by qualitative changes in spatiotemporal brain activity measured by electro- and magnetoencephalography. Here we show how these patterns can be decomposed into basic physiological events, i.e., evoked brain responses to acoustic tones and self-initiated finger movements. The frequency dependence of the amplitudes of these component responses may shed new light onto why spontaneous timing transitions occur in the first place.

Evoked Potentials, Auditory↗
PubMed2000

Mitochondrial defects by intracellular calcium overload versus endothelial cold ischemia/reperfusion injury.

Questions as to the critical stress factor and primary targets of cold ischemia/reperfusion (CIR) injury were addressed by comparing mitochondrial defects caused by (1) CIR injury and (2) intracellular Ca2+ overload. CIR was simulated in transformed human umbilical vein endothelial cell cultures (tEC) by 8 h cold anoxia in University of Wisconsin solution and reoxygenation at 37 degrees C. Intracellular Ca2+ concentrations were changed by permeabilization of suspended cells with digitonin in culture medium (RPMI, 0.4 mM Ca2+). Binding of free Ca2+ by ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid in RPMI or mitochondrial incubation medium served as controls. Extracellular Ca2+ protected the cell membrane against permeabilization. Mitochondrial functions were determined before and after permeabilization of the cell membrane. After CIR, mitochondrial respiratory capacity declined, but oxygen consumption remained coupled to adenosine triphosphate (ATP) production. In contrast, Ca2+ overload caused uncoupling of mitochondrial respiration. High intracellular Ca2+ overload, therefore, does not reproduce cold ischemia/reperfusion injury in endothelial cells.

Adenosine↗
PubMed2000

Fine-needle aspiration of granulocytic sarcomas: a morphologic and immunophenotypic study of seven cases.

Granulocytic sarcoma is an uncommon extramedullary, solid tumor of myeloid cells. Only rarely has this entity been diagnosed by fine-needle aspiration (FNA) cytology. This report encompasses the cytologic findings of FNAs from seven patients with granulocytic sarcomas, including four male and three female patients with a mean age of 52 years (range, 12 to 77 years). The aspirates were obtained from skin or subcutaneous tissue (four cases), testis (one case), posterior ileum (one case), lymph node (one case), and abdominal washing (one case). Morphology of the aspirates varied from well-differentiated to poorly differentiated cells showing little or no evidence of myeloid differentiation. Thorough search for evidence of myeloid differentiation and a high index of suspicion of granulocytic sarcoma are of paramount importance. In three cases, flow cytometric and immunocytochemical studies were applied to the FNA materials to confirm the myeloid lineage of the cells and the diagnosis. In the other four cases more than one site was involved by the tumor; once the diagnosis of granulocytic sarcoma was established with a biopsy, the FNA sufficed to confirm the diagnosis at another location. This study demonstrates that FNA cytology in conjunction with appropriate immunophenotyping can provide an accurate diagnosis of granulocytic sarcoma. Fine-needle aspiration can reduce the need for surgical intervention when combined with immunophenotypic studies and when additional anatomic sites are involved.

Adolescent↗
PubMed2000

Aggressive natural killer cell lymphoma presenting as an anterior mediastinal mass in a patient with acquired immunodeficiency syndrome.

We report a case of aggressive natural killer cell lymphoma presenting as an anterior mediastinal mass in an African-American man with acquired immunodeficiency syndrome. Histologically, the anterior mediastinal mass showed a diffuse dense infiltrate of atypical intermediate-sized and large lymphoid cells, as well as scattered immunoblasts with angiocentric and angiodestructive growth and extensive zonal necrosis. Similar lymphoid infiltrates were present in the patient's lungs, spleen, and bone marrow, accompanied by extensive lymphophagocytosis. Electron microscopic and cytologic examinations showed the presence of dense cytoplasmic granules. Immunophenotyping by flow cytometry and by immunohistochemistry yielded surface markers consistent with a natural killer cell lymphoma. The Epstein-Barr virus genome and monoclonality were detected by in situ hybridization and Southern blot analysis. Polymerase chain reaction confirmed the presence of type A Epstein-Barr virus. T-cell receptor gene rearrangement could not be identified by Southern blot analysis or polymerase chain reaction. To the best of our knowledge, this is the first reported case of designated natural killer cell lymphoma from the mediastinum, as well as the first reported case of natural killer cell lymphoma in a patient with acquired immunodeficiency syndrome. This tumor disseminated early and pursued a highly aggressive course. Epstein-Barr virus may play a role in the pathogenesis of this disease.

Adult↗
PubMed2000

An unusual variant of composite lymphoma: a short case report and review of the literature.

We recently encountered an unusual case of composite lymphoma arising in a 73-year-old man with a history of follicular small cleaved cell lymphoma. The neoplasm was composed of follicular small cleaved cell lymphoma and nodular sclerosing Hodgkin disease within a single groin lymph node. In addition to morphologic evidence, the immunologic studies performed in this case demonstrated the simultaneous occurrence of 2 separate lymphocytic proliferations. To the best of our knowledge, only one such histologic type has been reported in the literature.1 Hodgkin lymphoma can develop in patients with non-Hodgkin disease and vice versa, especially after treatment. The simultaneous occurrence of Hodgkin disease and non-Hodgkin lymphoma in a single lymph node is extremely rare. In this article, the relationship between Hodgkin disease and non-Hodgkin lymphoma is explored, possible explanations for the occurrence of composite lymphoma are discussed, and the literature is reviewed.

Aged↗
PubMed1999

Valence Isomerization of a 1,3-Diphosphacyclobutane-2,4-diyl: Photochemical Ring Closure to 2,4-diphosphabicyclo

The bond stretch isomer 1,3-diphosphacyclobutane-2,4-diyl 1 was transformed photochemically to give the previously unknown 2,4-diphosphabicyclo[1.1.0]butane 2, which itself can be converted thermally into gauche-1,4-diphosphabutadiene 3. The crystal structures of these three energy-rich valence isomers of 1,2-diphosphete have been determined. R=SiMe(3); Mes*=2,4,6-tBu(3)C(6)H(2).

Journal Article↗
PubMed1999

1,3-Diphosphacyclobutane-2,4-diyl-2-ylidenide: A Unique Carbene and Its Trimethylalane Complex.

A unique bonding situation is displayed by the lithium 1,3-diphosphacyclobutane-2,4-diyl-2-ylidenide 2 small middle dot[Li(thf)(n)](+) (Ar=2,4,6-tBu(3)C(6)H(2)) obtained by deprotonation of 1. According to ab initio calculations, the anion 2 can viewed as a cyclic bis(phosphanyl)carbene. Reaction with trimethylaluminum gives the complex 3 small middle dot[Li(thf)(4)](+), whose crystal structure is presented.

Journal Article↗
PubMed1999

Spatiotemporal reorganization of electrical activity in the human brain associated with a timing transition in rhythmic auditory-motor coordination.

We used a 61-channel electrode array to investigate the spatiotemporal dynamics of electroencephalographic (EEG) activity related to behavioral transitions in rhythmic sensorimotor coordination. Subjects were instructed to maintain a 1:1 relationship between repeated right index finger flexion and a series of periodically delivered tones (metronome) in a syncopated (anti-phase) fashion. Systematic increases in stimulus presentation rate are known to induce a spontaneous switch in behavior from syncopation to synchronization (in-phase coordination). We show that this transition is accompanied by a large-scale reorganization of cortical activity manifested in the spatial distributions of EEG power at the coordination frequency. Significant decreases in power were observed at electrode locations over left central and anterior parietal areas, most likely reflecting reduced activation of left primary sensorimotor cortex. A second condition in which subjects were instructed to synchronize with the metronome controlled for the effects of movement frequency, since synchronization is known to remain stable across a wide range of frequencies. Different, smaller spatial differences were observed between topographic patterns associated with synchronization at low versus high stimulus rates. Our results demonstrate qualitative changes in the spatial dynamics of human brain electrical activity associated with a transition in the timing of sensorimotor coordination and suggest that maintenance of a more difficult anti-phase timing relation is associated with greater activation of primary sensorimotor areas.

Acoustic Stimulation↗
PubMed1999

Correlational cuing as a function of target complexity and target-flanker similarity.

It is generally assumed that the correlational cuing effect (CE) between targets and correlated flankers is due to learning association between the flankers and their correlated responses. The present study challenges this view. Experiment 1 shows that the CE for targets composed of color is eliminated as soon as the correlation is removed. Experiment 2 shows that the CE during training is not due to association of the flankers with responses. Experiment 3 shows that at least some of the CE during training with the correlation is due to repetition priming of the display. Experiment 4 replicates the results of Experiment 1 for orientation targets. In Experiments 5-7, more typical tasks with letter targets are examined, and it is demonstrated that preexperimental similarity between targets and correlated flankers is crucial. The CE for correlated but dissimilar target-flanker pairs, similar to that for color and orientation targets, is confined to on-line processes that occur during training. The CE is transferred, however, for correlated and similar target-flanker pairs. We propose that, at least for the simple stimulus to response mapping used in our study, the CE is not due to learning at all. Instead it is due to (1) on-line processes, such as repetition priming, that occur during training with the correlation and (2) a regular flanker effect (see, e.g., B. A. Eriksen & C. W. Eriksen, 1974) that occurs for similar target-flanker pairs.

Adult↗