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Biomedical subjects

R Fiedler

Publications and source records attributed to R Fiedler.

At least 19 recordsLinked to original sources
PubMed2005

Ovarian cancer identification based on dimensionality reduction for high-throughput mass spectrometry data.

MOTIVATION: High-throughput and high-resolution mass spectrometry instruments are increasingly used for disease classification and therapeutic guidance. However, the analysis of immense amount of data poses considerable challenges. We have therefore developed a novel method for dimensionality reduction and tested on a published ovarian high-resolution SELDI-TOF dataset. RESULTS: We have developed a four-step strategy for data preprocessing based on: (1) binning, (2) Kolmogorov-Smirnov test, (3) restriction of coefficient of variation and (4) wavelet analysis. Subsequently, support vector machines were used for classification. The developed method achieves an average sensitivity of 97.38% (sd = 0.0125) and an average specificity of 93.30% (sd = 0.0174) in 1000 independent k-fold cross-validations, where k = 2, ..., 10. AVAILABILITY: The software is available for academic and non-commercial institutions.

Algorithms↗
PubMed2004

[Reconstructive foot surgery in cases of diabetic-neuropathic osteoarthropathy].

QUESTION: Neurogenic osteoarthropathy often results in a debilitating deformity of the foot which can not be handled conservatively. Indications for surgery are recurrent ulcers, deep tissue infection and decompensated statics with progressing deformity. External fixation as a possible method of correction has to show its efficiency and methods. METHODS: Between 1997 and 2003, 65 feet which could be examined retrospectively, were operated for neuroarthropathy in 21 women and 43 men. A diabetic polyneuropathy was present in 56 patients. In 59 cases, an external fixation was used while in nine cases Steinmann pins were used. Follow-up treatment consisted of mobilisation in a ankle-foot-orthosis (AFO) for up to a year. RESULTS: For diabetics, the mean duration of illness was 24.8 years (Type 1) and 13.7 years (Type 2). All feet were Levin stage 3 or 4 and for the classification types II-V. In five cases there was only luxation, another nine had a combination of luxation and osseous changes. Surgical revision was necessary in seven cases, sometimes more than once. Additional operations as the illness progressed were necessary 13 times, in six cases due to loss of correction. The application of a prosthesis was necessary in three cases following amputations in two patients after an average of 752 days. Pin infections and disturbances in healing wound were common but could be successfully treated conservatively and were independent of previous ulceration or infection. Within the first year after operation, 13.9% of the feet developed an ulcer. All of the patients could be mobilised with the help of an orthosis (47 cases) or orthopedic shoes (15 cases) CONCLUSIONS: External fixation is a suitable and variable method for correcting malalignment of the foot in cases of neuroarthropathy. It has a low complication rate and can be used for rapidly developing as well as non-progressing osteoarthropathies. In general, a fibrous ankylosis is the result of treatment, which allows pain free mobilisation under full weight bearing. In suitable cases, with a good alignment of the foot and good patient cooperation, the use of the AFO can be changed to orthopedic shoes after about 12 months.

Aged↗
PubMed2004

[Lower limb orthosis to relieve stress forces on the foot and its use in patients with diabetic neuropathic osteoarthropathy: Case examples].

In the daily routine of treating patients with diabetic neuropathic osteoarthropathy (DNOAP), their history often reveals a prolonged course of therapy caused in part by incorrect diagnosis but also by inadequate provision of orthopedic devices. A "classic" case is that of undetected osteoarthropathy, which is erroneously interpreted as osteomyelitis. Thus, subsequent to frustrating attempts at therapy and persistence of the clinical symptoms, patients are not infrequently "offered" the option of amputation, which is performed quite proximal to the osseous lesion to "ensure treatment success." The fact that major amputations lead to a statistically significant decrease of the patient's life span is usually not taken into consideration during the decision making process for amputation. Orthopedic surgical procedures to preserve the leg should be given precedence for the sake of maintaining quality of life just as orthopedic devices and orthopedic shoes should be preferred to retain mobility before amputation is indicated in patients with DNOAP. The cases reports presented here should encourage others to implement treatment concepts with the aim of avoiding unnecessary amputations.

Aged↗
PubMed2002

[First clinical experience with a full-size, flat-panel detector for imaging the peripheral skeleton - Part II: Post-processing with a newly developed adaptive autowindow algorithm].

PURPOSE: of the second part of the investigation was the evaluation of a newly developed adaptive autowindow algorithm in comparison to the system processing radiographs of the wrist and ankle to further optimize the image quality with softcopy reading. MATERIAL AND METHODS: All 120 radiographs of the wrist and all 100 radiographs of the ankle used in the 1st part of this paper were processed with the adaptive autowindow algorithm. The evaluation was again performed by 5 radiologists with softcopy reading. For the data analysis a variation of the Visual Grading Analysis (VGA) was used. RESULTS: Up to 19 % of the wrist radiographs and 2 % of the ankle radiographs processed with the system software had to be processed manually afterwards to get acceptable results. By the application of the adaptive autowindow algorithm a manual post-processing was no longer necessary. Highly significant (p less-than-or-equal 0.001) differences for all criteria to be evaluated were found for the wrist radiographs and in the case of the ankle radiographs for the bone contrast, the contrast in soft-tissue regions, the fine details in the bone and the artifacts, the adaptive autowindow algorithm performed always better than the system software. CONCLUSION: Using half of the exposition dose on a flat-panel detector, an optimized post-processing leads to comparable or better results compared to the conventional film-screen-system concerning the image quality.

Algorithms↗
PubMed2001

[External fixator for reconstruction of foot statics in neurogenic osteoarthropathies].

The localization of neurogenic osteopathy in the hindfoot often results in deformities which cannot be corrected by conservative methods. Indications for operation are recurring ulcers, deep infection, and reduced stability with progressive deformity. The aim of this study was to ascertain whether external fixation enables reestablishment of foot stability even when the osteoarthropathic processes have not entirely ceased. A bilaterally mounted Hoffman 2 fixator was used for open repositioning and restabilization on 14 patients with osteoarthropathy of the hindfoot: 12 had diabetes mellitus and 13 had florid processes. Revision with axial correction was necessary in 2 patients. One underwent amputation according to Syme and received a prosthesis. Thirteen were completely remobilized: ten were fitted with an orthosis and three with a rigid orthopedic shoe. Complicated deformities of the hindfoot from neurogenic arthropathy can be satisfactorily restabilized in the edematous and demineralizing stages by surgery and the application of external fixation.

Adult↗
PubMed2001

[First clinical experience with a full-size, flat-panel detector for imaging the peripheral skeletal system].

PURPOSE: This investigation was intended to show that exposures of the peripheral skeleton system can be done with half of the dose used for conventional screen-film systems with a full-size CsI/a-Si flat panel detector. MATERIAL AN METHODS: 120 exposures of the wrist and 100 exposures of the ankle have been made on a full-size flat panel detector system (43 x 43 cm). The patient dose has been reduced by a factor of two compared to conventional images. Five radiologists evaluated every image as a softcopy and a hardcopy image. For the evaluation, a variation of the Visual Grading Analysis (VGA) without reference images was used. For the determination of the patient entrance dose, measurement of a phantom were performed. RESULTS: A dose reduction of about 50 % is possible with the same or even better image quality in routine diagnostics. Only 3 % of the ankle and approx. 21 % of the wrist exposures required a postprocessing. Exposures with implants did not show any artifacts and some of the those achieved better evaluation results compared with exposures without implants. CONCLUSION: A halving of the patient dose is possible with acceptable results for the image quality. The effect of an improved image processing remains to be evaluated. The patient entrance dose is suitable for an evaluation of a radiographic detector and especially for a dose-referred comparison of digital X-ray units.

Ankle Joint↗
PubMed2001

Is interleukin-6 concentration in the dialysate of continuous ambulatory peritoneal dialysis patients a prognostic parameter in peritonitis?

In continuous ambulatory peritoneal dialysis (CAPD) patients, peritonitis is a dangerous complication. Chemical examinations in the dialysate can be successfully used to assess permeability disturbances, hemostatic balance, and (for early detection and follow-up) cellular inflammatory reaction. In 7 CAPD patients (age: 50 +/- 15 years; dialysis duration: 40 +/- 24 months) with peritonitis episodes, and in 17 age-matched CAPD patients (age: 50 +/- 13 years; dialysis duration: 29 +/- 18 months) without peritonitis, we examined daily dialysate cell count (CC) and concentrations of albumin (ALB), immunoglobulin G (IgG), thrombin-antithrombin III complex (TAT), D-dimer (DD), and interleukin-6 (IL-6) after the long dwell (8-10 hours) over an interval of at least 14 days. In CAPD patients with peritonitis episodes, all parameters (CC, ALB, IgG, TAT, DD, IL-6) were significantly increased in the first days [IL-6 mean: 25,190 pg/mL (range: 2560-52,708 pg/mL) vs 66 pg/mL (range: 21-163 pg/mL)]; then, up to day 14 after successful therapy with antibiotics, the levels showed no differences as compared with CAPD patients without peritonitis. In the case of relapse of peritonitis (4 cases), concentration of IL-6 rose again on day 14, 1 day earlier than did the other parameters. Determination of IL-6 in the dialysate is a reliable prognostic parameter for the course of peritonitis (start, end, relapse) in CAPD patients.

Adult↗
PubMed2000

An electrophysiological study of the insertion of overt response choice.

Using electrophysiological measures, the authors studied changes in prestimulus state, stimulus identification, and response-related processing when, in a go/no-go task, forced choice between 2 overt go responses was inserted. The authors observed decreased prestimulus motor preparation (electromyogram), no change in stimulus identification time (selection negativity), a minor increase in response selection time (lateralized readiness potential), a large increase in response preparation time (lateralized readiness potential), a minor effect on response execution time (electromyogram), and a decrease in the activation of a response-inhibition process on no-go trials (frontal event-related potential). The existence of the response-inhibition process was verified by the presence of inverted lateralized readiness potentials on no-go trials. Pure insertion of response choice in a task seems impossible because the choice between activation and inhibition (go/no-go) always seems already present.

Adolescent↗
PubMed2000

Insulin-like growth factor system components in hyperparathyroidism and renal osteodystrophy.

BACKGROUND: The insulin-like growth factor (IGF) system plays a key role in regulation of bone formation. In patients with renal osteodystrophy, an elevation of some IGF binding proteins (IGFBPs) has been described, but there is no study measuring serum levels of both IGF-I and IGF-II as well as IGFBP-1 to -6 in different forms of renal osteodystrophy and hyperparathyroidism. METHODS: In a cross-sectional study, we investigated 319 patients with mild (N = 29), moderate (N = 48), preuremic (N = 37), and end-stage renal failure (ESRF; N = 205). The ESRF group was treated by hemodialysis (HD; N = 148), peritoneal dialysis (PD; N = 27), or renal transplantation (RTX; N = 30). As controls without renal failure, we recruited age-matched healthy subjects (N = 87) and patients with primary hyperparathyroidism (pHPT; N = 25). Serum levels of total and free IGF-I, IGF-II, IGFBP-1 to -6, and biochemical bone markers including intact parathyroid hormone (PTH), bone alkaline phosphatase (B-ALP), and osteocalcin (OSC) were measured by specific immunometric assays. IGF system components and bone markers were correlated with clinical and bone histologic findings. Mean values +/- SEM are given. RESULTS: With declining renal function a significant increase was measured for IGFBP-1 (range 7- to 14-fold), IGFBP-2 (3- to 8-fold), IGFBP-3 (1.5- to 3-fold), IGFBP-4 (3- to 19-fold), and IGFBP-6 (8- to 25-fold), whereas IGFBP-5 levels tended to decrease (1.3- to 1. 6-fold). In contrast, serum levels of IGF-I, free IGF-I, and IGF-II remained constant in most patients. Compared with renal failure patients, pHPT patients showed a similar decline in IGFBP-5 levels and less elevated levels of IGFBP-1 (3.5-fold), IGFBP-2 (2-fold), IGFBP-3 (1.2-fold), and IGFBP-6 (4-fold) but no elevation of IGFBP-4 levels. In all subjects, free and total IGF-I levels showed significant negative correlations with IGFBP-1, IGFBP-2, and IGFBP-4 (that is, inhibitory IGF system components) and significant positive correlations with IGFBP-3 and IGFBP-5 (that is, stimulatory IGF system components). A positive correlation was observed between IGF-II and IGFBP-6. ESRF patients with mixed uremic bone disease and histologic evidence for osteopenia revealed significantly (P < 0.05) higher levels of IGFBP-2 and IGFBP-4 but lower IGFBP-5 levels. Histologic parameters of bone formation showed significant positive correlations with serum levels of IGF-I, IGF-II, and IGFBP-5. In contrast, IGFBP-2 and IGFBP-4 correlated positively with indices of bone loss. Moreover, dialysis patients with low bone turnover (N = 24) showed significantly (P < 0.05) lower levels of IGFBP-5, PTH, B-ALP, and OSC than patients with high bone turnover. CONCLUSION: Patients with primary and secondary hyperparathyroidism showed lower levels of the putative stimulatory IGFBP-5 but higher levels of IGFBP-1, -2, -3, and -6, whereas total IGF-I and IGF-II levels were not or only moderately increased. The marked increase in serum levels of IGFBP-4 appeared to be characteristic for chronic renal failure. IGFBP-5 correlated with biochemical markers and histologic indices of bone formation in renal osteodystrophy patients and was not influenced by renal function. Therefore, IGFBP-5 may gain significance as a serological marker for osteopenia and low bone turnover in long-term dialysis patients.

Adult↗
PubMed2000

Preparing nursing students for contemporary practice: restructuring the psychomotor skills laboratory.

The restructured laboratory experience offered a safe environment that supported student experimentation with psychomotor skills and self-initiated approaches to problem solving. Restructuring psychomotor laboratory experiences with emphasis on communication and conceptualization of principles supported students to begin addressing clinical problems with flexibility, creativity, and the premise for lifelong skill acquisition. Students who have skills that extend beyond technique will inevitably be better prepared to meet the demands of health care systems and patients now and in the future.

Clinical Competence↗
PubMed1999

[Functional outcome and quality of life at least 6 months after pneumonectomy--effect of operation, adjuvant therapy, tumor stage, sex, type of pneumonia and recurrence].

This study reports on the results of a checkup carried out on 38 patients subjected to an extended cancer aftercare examination at least 6 months after pneumectomy because of bronchial carcinoma, 12 of these patients receiving adjuvant chemotherapy and/or radiotherapy. Lung function data determined by body plethysmography were measured, as well as the quality of life, using the Karnofsky and Spitzer indices as well as QLQ-C30 of the EORTC. In addition, anamnestic data and postoperative ECG and blood gas analysis results were recorded. The most important findings concern restricted lung function due to pneumectomy, an IVC decrease by 33.3%, a drop in FEV1 by 27.3% and a reduction of the total lung capacity (TLC) by 14%. Moreover, a distinctly increased right heart load was seen in 23.4% of all patients. The quality of life tests revealed a slightly reduced quality of life in the external assessment indices according to Karnofsky (86 +/- 11%) and Spitzer (8.6 +/- 1.2). Self-assessment by QLQ-C30 of the EORTC, however, evidenced a clear reduction of the global quality of life (54.2 +/- 15.6) and role function, a moderate decrease of physical, emotional, cognitive and social functioning as well as a greatly increased incidence of the symptoms fatigue, dyspnea, sleep disturbances and pain after surgery. Adjuvant therapy applied in 12 patients had no significant influence, neither on lung function parameters nor on the quality of life. A more advanced tumour stage or a relapse, however, will adversely affect the quality of life.

Adult↗
PubMed1998

[Mutilating complex trauma of the pelvis].

Traumatic hemipelvectomy is a rare, but devastating pelvic injury with few survivors reported in the literature. We report on a 19-year-old motorcyclist with a near-total hemipelvectomy. After a complicated course, the patient survived with good potential for a functional level of activity. We review the experience of other authors and give details on the management of one of the most challenging injuries confronting surgeons. Successful treatment requires extraordinary efforts and multidisciplinary team cooperation.

Adult↗
PubMed1998

Comparing consumer and clinician values for alternative functional states: application of a new feature trade-off consensus building tool.

OBJECTIVE: To present the Features-Resource Trade-Off Game (Features Game) as a new method for comparing preferences for alternative outcomes among different groups of people. DESIGN: The Features Game is illustrated by comparing preferences for recovery among the 18 functional status items making up the Functional Independence Measure. Methods involved trading levels of independence (resources) across the different items (features). SETTING: Ten community-dwelling consumers with physical disabilities and 10 rehabilitation clinicians participated in four separate expert panels-two in Houston and two in Philadelphia. MAIN OUTCOME MEASURES: Five sets of hierarchical stages defined by the four separate panels specifying the profiles of function believed to most foster independent living. RESULTS: Cognitive and communication skills were selected preferentially over the recovery of physical tasks by all panels, but, in comparison to clinicians, consumers were more willing to accept mild deficits in cognitive skills as trade for realizing earlier recovery of physical abilities. CONCLUSION: The overwhelming choice of cognitive and communication abilities over physical abilities suggests a need to enhance therapeutic efforts in those areas. More subtle differences in consumer and clinician preferences emphasize the importance of establishing consumer-oriented goals.

Activities of Daily Living↗
PubMed1998

Liver biopsy is a useful predictor of response to interferon therapy in chronic hepatitis C.

AIM: To evaluate the usefulness of easily assessable morphological parameters in liver biopsies in order to predict efficacy of interferon-alpha (IFN) treatment in patients with chronic hepatitis C. METHODS AND RESULTS: Inflammatory activity and fibrosis (according to Scheuer), and the hepatic iron content (according to Rowe and DiBisceglie) were assessed in pre-treatment liver biopsies of 73 de novo patients with chronic hepatitis C. Furthermore the presence of fat, lymphoid aggregates, and bile duct lesions was evaluated. With respect to IFN therapy patients were classified as responders alanine aminotransferase (ALT) normal and negative hepatitis C virus (HCV) RNA in serum at the end of treatment, n = 33) or non-responders (n = 40). Non-responders had more advanced fibrosis (P = 0.0001) and more extensive iron storage (P = 0.0008) than responders. In contrast absence of stainable iron was frequently (46%) associated with sustained response. Absence of fat droplets in hepatocytes was associated with response (P = 0.0001). Stepwise logistic regression analysis indicated that the stage of fibrosis, the hepatic iron grade, and the presence or absence of fat were independent predictors of response. CONCLUSIONS: Liver biopsy provides useful information for selection of patients with hepatitis C for IFN therapy.

Adult↗
PubMed1997

Rational use of polymerase chain reaction--based detection of viral genomes in patients with serologic markers of hepatitis B or C virus infection.

We studied the value of additional diagnostic information obtained by detection of hepatitis B virus (HBV) DNA or hepatitis C virus (HCV) RNA using the qualitative polymerase chain reaction (PCR) in patients with serologic markers of hepatitis B or hepatitis C virus infection. In HBV infection, all HBsAg+HBeAg+ patients and all HBsAg+HBeAg- patients with alanine aminotransferase (ALT) levels > 100 U/L were positive for HBV-DNA by PCR, whereas in HBsAg+HBeAg- patients with ALT < 100 U/L 58% and in HBsAg+HBeAg- patients with normal aminotransferase 45% were found to be positive. In HBsAg+ patients no further clinically useful information can be obtained by PCR as the presence of HBsAg proves infection. However in three of 42 (7%) patients with markers of past HBV infection (antiHBs and/or antiHBc+) HBV-DNA was detected in the serum. Similarly, in some patients with acute hepatitis B HBV-DNA was demonstrable up to four months after the disappearance of HBsAg from serum, pointing to persistence of viremia despite the loss of serological markers of ongoing HBV infection. Demonstrating ongoing HBV infection in patients with serological markers of past infection is valuable additional information in only selected patients. In HCV infection, 10% of anti-HCV+ patients with increased ALT levels had a negative serum HCV-RNA. However, in 20% of those patients HCV-RNA was demonstrated in a serum sample collected later during follow-up, indicating that a single negative HCV-RNA determination cannot be taken as evidence for the resolution of infection.

Adolescent↗