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Biomedical subjects

R Fischer

Publications and source records attributed to R Fischer.

At least 937 records · Page 52Linked to original sources

Agnogenic myeloid metaplasia (AMM)--correlation of bone marrow lesions with laboratory data: a longitudinal clinicopathological study on 114 patients.

A clinicopathological study was performed on 114 patients (46 male/68 female, median age 67 years) with the diagnosis of agnogenic myeloid metaplasia (AMM) respectively primary osteo-myelofibrosis which was not preceded by any other or allied subtype of chronic myeloproliferative disorders. On admission patients revealed a striking variability of laboratory data as well as different histopathological features of initial bone marrow biopsies. For this reason discrimination was done into two groups based on bone marrow findings: group I patients (n = 46, 19 male/27 female) showed a hypercellular marrow without or only borderline (n = 24) to slight (n = 22) reticulin fibrosis and group II cases (n = 68, 27 male/41 female) displayed coarse bundles of collagen fibres (n = 18) frequently accompanied by osteosclerosis (n = 50). Statistical analysis of the corresponding initial hematological findings resulted in significant differences. These differences concerned also the complications occurring during the lengthy course of disease, which included a higher incidence of pancytopenia and severe marrow failure with hemorrhage and blast crisis in group II patients. However, overall survival time was not different in both groups. This may be related to the similarity of age distribution (64 resp. 65 years) and its significant association with arteriosclerotic vascular lesions. Consequently acute myocardial infarction and congestive heart failure were frequent causes of death in addition to infections due to marrow failure and blast crisis. Repeated bone marrow biopsies in 24 patients revealed an insidious transition from hypercellular lesions (group I) into advanced fibro-osteosclerotic changes (group II) concurring with laboratory data. Therefore our discrimination into two groups of patients represents variable stages or static histological and corresponding hematologic features in the evolution of a dynamic disease process in AMM.

Aged↗

Characterization of giant cells in Hodgkin's lymphomas by immunohistochemistry applied to randomly collected diagnostic biopsies from the German Hodgkin Trial.

A panel of 10 monoclonal antibodies reactive with formalin-resistant epitopes was applied to characterize the giant cells of the Reed-Sternberg, Hodgkin, and lacunar cell types in diagnostic biopsies from the German Hodgkin Trial. The 94 tissue samples examined had been sent to the Reference Center by 44 different laboratories which made the initial diagnoses. A board of four referees re-classified the primary diagnoses established by the 44 different histopathologists, providing subtyping of Nodular Sclerosis according to Bennett et al. (1985, 1989). Only cases with unequivocal agreement among the referees and which satisfied standards of fixation and embedding were included. Giant cells stained positively with: Ber-H2 in 92 per cent (81/88), LN-2 in 86.4 per cent (76/88), and DAKO-M1 in 72.2 per cent (64/88) of cases in which the lymphocyte predominance type was not included. Positive staining was quite rare with the other seven monoclonal antibodies. No significant difference in reactivity was revealed between giant cells of Reed-Sternberg, lacunar or Hodgkin cell types. Approximately one third of the cases were negative for at least one of the markers, Ber-H2, LN-2 or DAKO-M1. The lymphocytic and histiocytic cells in lymphocyte predominance Hodgkin's disease displayed a distinctive staining pattern with positivity for B-cell markers, whereas DAKO-M1 and Ber-H2 were predominantly negative. Finally, we found that randomly collected blocks of primary biopsies permit reliable immunostaining by this panel of monoclonal antibodies, since our results agree with results from the literature obtained from biopsies processed according to more uniform protocols for fixation and embedding.

Antibodies, Monoclonal↗

The impact of the Mammography Quality Standards Act on the availability of mammography facilities.

BACKGROUND: The Mammography Quality Standards Act (MQSA) became effective October 1, 1994, and requires all mammography facilities to meet quality standards as promulgated by the Food and Drug Administration (FDA). The FDA undertook an assessment of the MQSA federal certification requirements on the availability of mammography facilities. METHODS: A survey of states on mammography facility closures between October 1, 1993, and October 1, 1994, was conducted. MapInfo software was used to link zip codes to demographic databases. The characteristics of closed facilities were compared to certified facilities as of December 15, 1994. RESULTS: A total of 369 facilities (3.5%) had closed. This closure rate was comparable to previous years' rates (2.5-10%). As of December 15, 1994, 10,142 certified facilities were operating. Relative to their distribution in the United States, closures in rural areas were proportional, but there were more facility closures in the minority areas and in poverty areas. However, the relative distributions of facilities to these areas' populations were unchanged. CONCLUSIONS: Impact on facility availability has been minimal.

Female↗

A comparison of analytical methods for the study of fractional Brownian motion.

Fractional Brownian motion (FBM) provides a useful model for many physical phenomena demonstrating long-term dependencies and l/f-type spectral behavior. In this model, only one parameter is necessary to describe the complexity of the data, H, the Hurst exponent. FBM is a nonstationary random function not well suited to traditional power spectral analysis however. In this paper we discuss alternative methods for the analysis of FBM, in the context of real-time biomedical signal processing. Regression-based methods utilizing the power spectral density (PSD), the discrete wavelet transform (DWT), and dispersive analysis (DA) are compared for estimation accuracy and precision on synthesized FBM datasets. The performance of a maximum likelihood estimator for H, theoretically the best possible estimator, are presented for reference. Of the regression-based methods, it is found that the estimates provided by the DWT method have better accuracy and precision for H > 0.5, but become biased for low values of H. The DA method is most accurate for H < 0.5 for a 256-point data window size. The PSD method was biased for both H < 0.5 and H > 0.5.

Bias↗

Hematopoietic turnover index in reactive and neoplastic bone marrow lesions: quantification by apoptosis and PCNA labeling.

In order to determine the dynamics of hematopoietic cell turnover, proliferative activity and incidence of apoptosis (programmed cell death) were evaluated in bone marrow trephine biopsies. Selection of patients (20 in each group) included in addition to a control group, idiopathic thrombocytopenia (ITP), reactive thrombocytosis (TH), secondary polycythemia-smokers' polyglobuly (PG), primary (essential-hemorrhagic) thrombocythemia (PTH), polycythemia vera (PV), and finally acute myeloid leukemia (AML). Apoptosis was demonstrated by the in situ end-labeling technique (ISEL) and proliferative activity by applying the monoclonal antibody PC10 raised against proliferating cell nuclear antigen (PCNA). To assess dynamic features of hematopoiesis, an index was calculated consisting of the ratio between PCNA-positive nuclei and the apoptotic cell fraction. This factor was termed the hematopoietic turnover index (HTI). Morphometric analysis revealed that the HTI was significantly increased in AML and PV. According to cell culture studies both disorders are characterized by either a prevalent proliferation of the myeloid or erythroid cell mass. On the other hand, PG, PTH, and TH showed no relevant enhancement of this index in comparison to the control specimen. In vitro experiment results are in keeping with the finding that PG and PTH are not associated with a significant expansion of the erythroid lineage (CFU-E). Similar to ITP and TH, in PTH megakaryocyte proliferation (CFU-MEG) is the predominant feature of cell turnover. Differences between PTH and TH are in line with the reduced in vitro formation of CFU-MEG in the latter disorder. In conclusion, our in situ study on turnover rates of the bone marrow in various neoplastic and reactive lesions extends previous experimental data on hematopoietic cell kinetics.

Acute Disease↗

[SQUID-biosusceptometry in iron overloaded patients with hematologic diseases].

BACKGROUND: For the long-term survival of iron-loaded patients, early and well adjusted treatment with iron chelators is of crucial importance, especially in children. Basis of the adequate treatment are appropriate diagnostic parameters which are capable to monitor the range of the individual iron burden. PATIENTS: In the time period between 1989 and 2001, the status of iron loading was investigated in 1112 patients with post transfusion siderosis. METHODS: The iron concentration in liver and spleen was quantified by SQUID-biosusceptometry. Using these values, the whole body iron stores were calculated. RESULTS AND DISCUSSION: Based on a large number of patients with secondary siderosis, the benefit of SQUID-biosusceptometry for non-invasive liver iron quantification was evaluated retrospectively. In patients under treatment with deferoxamin, a new therapeutic DFO-index was defined which respects liver iron concentration instead of serum ferritin. This results in a more reliable information about DFO overdosing in a given patient.

Adolescent↗

[Use of ultrasonography in the diagnosis of infections in the locomotor apparatus--possibilities and limitations].

Significance of sonography in the detection of soft tissue infections is unclear and discussed controversial in literature. In a retrospective study sonograms of 40 hematomas and 23 infections were evaluated to examine the possibility of detecting infections by means of sonography alone. Accumulation of fluid, however, could not be differentiated by the established sonomorphological criteria. Especially in postoperative infections with unclear clinical pattern no differentiation between hematoma and abscess could be made. Only ultrasonically guided transcutaneous needle aspiration biopsy can prove the character of sonographic findings.

Abscess↗

[Fluorescence spectroscopy in selective percutaneous nucleotomy using the excimer laser--experimental studies].

Our intention was to test fluorescence spectroscopy as a possibility for selective laser ablation. In an experimental setup a XeCl excimer laser (308 nm) with pulse energies between 5 and 50 mJ was used for fluorescence excitation in 20 human and 100 pig vertebral segments. Tissue fluorescence was detected via a quartz fiber bundle and analyzed by a polychromator and optical multichannel analyzer. Both low and high energy levels led to a broad band fluorescence of nucleus pulposus, intervertebral muscle, spinal cord and vertebral end plate and a typical fluorescence of anulus fibrosus with peak maxima at 385 and 435 nm. Tissue fluorescence was independent of surrounding medium (with air and normal saline used) and excitation energy. Borderlines between different tissues could be clearly indicated in all cases. Using intensity rations at 350, 385 and 435 nm (I1 = I350/I385, I2 = I385/I435) tissue discrimination was possible in all cases. This results demonstrate, that discrimination between intervertebral disc and surrounding tissue is possible and could be used for selective percutaneous laser nucleotomy in the near future.

Animals↗