Analysis of historical negative control group data from the rat in vivo micronucleus assay.

A database of micronuclei counts for historical negative control data from rat in vivo micronuclei tests performed in 10 different laboratories was established. Data were available from over 4000 negative control rats from 10 laboratories. The mean frequency of micronucleated cells (MN)/1000 cells ranged from 0.44 to 2.22, a 5-fold range. Overall there were no major sex or strain differences in frequency, although there were some small but statistically significant differences within laboratories. There was appreciable variability between experiments compared with variability within experiments in some laboratories. No specific factor was identified which could explain this variability although it was noted that many different vehicles were used in the experiments. It is hoped that these data will help laboratories beginning studies with the rat micronucleus assay and those involved in the assessment of micronucleus assay results.

[Determination of renal function in clinical routine: which is the best method?]. / Bestimmung der Nierenfunktion im klinischen Alltag--welche Methode ist die beste?

BACKGROUND AND OBJECTIVE: Accurate quantification of renal function is important for diagnosing and monitoring progression of renal diseases and for calculating adequate doses of drugs that are excreted by the kidneys. Gold-standard procedures are too complex for routine clinical use. At the moment there are several formulae to choose from, all said to estimate renal function precisely enough for clinical purposes. It was the aim of this study to compare the accuracy of several of these in clinical routine. PATIENTS AND METHODS: The results of inulin clearance were compared with those calculated by the Cockcroft-Gault formula (CGF), abbreviated diet modification of renal disease (MDRD) formula, the Mayo formula and the cystatin C-based formula as proposed by Larsson et al. Included were 189 in-patients (aged 20-87, 40% of them women, range of inulin clearance 8-244 ml/min/1,73m). In addition, inulin clearance was compared with creatinine clearance in 142 patients (aged 20-87 years, 42% women. Inulin clearance 13-244 ml/min/1,73m). Bland-Altman diagrams were drawn and mean bias and standard deviation of the formulae were compared with inulin clearance, as were sensitivity and specifity for diagnosing reduced renal function. RESULTS: All formulae underestimated glomerular filtration rate (GFR), with CGF and MDRD formulas giving the best results. These formulae had a mean bias of -16.2 (SD 24.8) and -18.2 (SD 25.6) ml/min/1,73m (2) , respectively. All creatinine-based formulae showed a high sensitivity and specifity for diagnosing a GFR below 60 ml/min/1,73m (2). CONCLUSION: None of the estimating formulae can replace inulin clearance with adequate accuracy. In our patients the cystatin C formula of Larsson et al showed no advantage. But the MDRD formula, which can be calculated without knowing body weight, is as accurate and precise as CGF.

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.

[Reconstructive foot surgery in cases of diabetic-neuropathic osteoarthropathy]. / Rekonstruktive Fusschirurgie bei diabetisch-neuropathischer Osteoarthropathie.

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.

[Lower limb orthosis to relieve stress forces on the foot and its use in patients with diabetic neuropathic osteoarthropathy: Case examples]. / Die fussentlastende Unterschenkelorthese und ihre klinische Anwendung bei Patienten mit diabetisch-neuropathischer Osteoarthropathie. Fallbeispiele.

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.

[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]. / Erste klinische Erfahrungen mit einem grossformatigen Flächendetektorsystem bei Aufnahmen des peripheren Skelettsystems - Teil 2 : Nachverarbeitung mit einem neu entwickelten adaptiven Autofensteralgorithmus -

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.

[First clinical experience with a full-size, flat-panel detector for imaging the peripheral skeletal system]. / Erste klinische Erfahrungen mit einem grossformatigen Flächendetektorsystem bei Aufnahmen des peripheren Skelettsystems - Teil 1: halbierte Patientendosis -

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.

Characteristics of persons rehospitalized after stroke rehabilitation.

OBJECTIVE: To develop classification models for risk of hospital readmission 80 to 180 days after discharge based the demographic and functional characteristics of persons discharged from acute inpatient rehabilitation after stroke. DESIGN: Retrospective, using information from US facilities subscribing to the Uniform Data System for Medical Rehabilitation (UDS(MR)). SETTING: Information submitted to the UDS(MR) from 1994 through 1996 by 167 hospital and rehabilitation facilities from 40 states was examined. PARTICIPANTS: A total of 15,992 records of patients (mean age +/- standard deviation, 70.97 +/- 12.19yr) with a diagnosis of stroke were included in the final sample. The sample included 52.7% women and was 80% non-Hispanic white with an average length of stay (LOS) of 25.31 +/- 14.72 days. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Six subscales of the FIM instrument (self-care, sphincter control, transfers, locomotion, communication, social cognition), total FIM, and other predictor variables for regression analysis (gender, age, ethnicity, marital status, prehospital living setting, LOS, primary payer source, level of function-related group). RESULTS: A logistic regression model included the following statistically significant variables (p <.05): ethnicity, sphincter control, self-care ability, gender, and LOS. The greatest variability occurred among men. Exactly 18.1% of non-Hispanic white men and 17.9% of African-American men were rehospitalized. In contrast, only 10.1% of Hispanic men and 11.4% of Asian men were rehospitalized. The odds of rehospitalization were lowest for Hispanic men. CONCLUSION: As prospective payment systems are introduced for postacute care, it is important that the relationship among functional abilities, demographic characteristics, and incidence of hospital readmission following medical rehabilitation be examined.

Comparison of logistic regression and neural networks to predict rehospitalization in patients with stroke.

CONTEXT: Rehospitalization following inpatient medical rehabilitation has important health and economic implications for patients who have experienced a stroke. OBJECTIVE: Compare logistic regression and neural networks in predicting rehospitalization at 3-6-month follow-up for patients with stroke discharged from medical rehabilitation. DESIGN: The study was retrospective using information from a national database representative of medical rehabilitation patients across the US. SETTING: Information submitted to the Uniform Data System for Medical Rehabilitation from 1997 and 1998 by 167 hospital and rehabilitation facilities from 40 states was examined. PARTICIPANTS: 9584 patient records were included in the sample. The mean age was 70.74 years (SD = 12.87). The sample included 51.6% females and was 77.6% non-Hispanic White with an average length of stay of 21.47 days (SD = 15.47). MAIN OUTCOME MEASURES: Hospital readmission from 80 to 180 days following discharge. RESULTS: Statistically significant variables (P <.05) in the logistic model included sphincter control, self-care ability, age, marital status, ethnicity and length of stay. Area under the ROC curves were 0.68 and 0.74 for logistic regression and neural network analysis, respectively. The Hosmer-Lemeshow goodness-of-fit chi-square was 11.32 (df = 8, P = 0.22) for neural network analysis and 16.33 (df = 8, P = 0.11) for logistic regression. Calibration curves indicated a slightly better fit for the neural network model. CONCLUSION: There was no statistically significant or practical advantage in predicting hospital readmission using neural network analysis in comparison to logistic regression for persons who experienced a stroke and received medical rehabilitation during the period of the study.

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.

[External fixator for reconstruction of foot statics in neurogenic osteoarthropathies]. / Der Fixateur externe zur Rekonstruktion der Fussstatik bei neurogenen Osteoarthropathien.

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.

Satisfaction with medical rehabilitation in patients with cerebrovascular impairment.

OBJECTIVE: Overall satisfaction has important social and economic implications for patients who have received inpatient medical rehabilitation. We conducted this study to examine the overall satisfaction level at 3- to 6-mo follow-up for inpatients with cerebrovascular impairments discharged from medical rehabilitation. DESIGN: The study was retrospective using information from a national database representative of medical rehabilitation patients across the United States. Information submitted in 1997 and 1998 to the Uniform Data System for Medical Rehabilitation by 177 hospital and rehabilitation facilities from 40 states was examined. The final sample included 8,900 patient records. The main outcome measure was the level of satisfaction with medical rehabilitation at 80-180 days postdischarge follow-up. RESULTS: A logistic regression model including ten independent variables was used to predict satisfied vs. dissatisfied at follow-up. Three statistically significant variables were included in the final model and correctly classified 95.1% of the patients. Higher FIM instrument discharge scores were associated with increased satisfaction. Further analysis of the FIM instrument subscales indicated that higher ratings in transfers, social cognition, and locomotion were significantly associated with increased satisfaction. CONCLUSION: We identified several functional variables associated with increased satisfaction after medical rehabilitation in persons with stroke. The ability to objectively assess patient satisfaction is important as consumer-based outcome measures are integrated in accreditation and healthcare evaluation.

Length of stay and hospital readmission for persons with disabilities.

OBJECTIVES: Length of stay (LOS) and hospital readmission for persons receiving medical rehabilitation were examined. METHODS: A total of 96,473 patient records (1994-1998) were analyzed. Mean age of patients was 68.97 years; 61% were female and 83% were non-Hispanic White. RESULTS: A decrease in LOS of 6.07 days (SD = 3.23) and increase in hospital readmission were found across all impairment groups (P < .001). Readmission increases ranged from 6.7% for amputations to 1.4% for orthopedic conditions. LOS was longer (2.1 days) for readmitted patients (P < .01). Age was not a significant predictor of rehospitalization. CONCLUSIONS: Understanding variables associated with rehospitalization is important as prospective payment systems are introduced for postacute care.

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.

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.