Practice and carryover effects when using small interaction devices.

The use of interaction devices in modern work often challenges the human motor system, especially when these devices introduce unfamiliar transformations to the user. In this paper we evaluated expert performance and skill differences between experts and novices when using small motion- and force-controlled interaction devices (touchpad and mini-joystick) in an applied text-editing task. Firstly, experts performed better with their familiar input device than with an unfamiliar one. Particularly touchpad experts operating the unfamiliar mini-joystick showed highly asymmetric carryover costs. Results showed that the efficient performance of experts depended on domain-specific skills, which were not transferable. Secondly, with considerable practice (more than observed for simple and short tasks) novices were brought up to higher levels of performance. The motion-transformation between hand and cursor action was easier in understanding and application than the force-transformation. Thus, the touchpad was used more efficiently than the mini-joystick. In conclusion, practice effects found so far are considerably underestimated when it comes to an applied task. The results give reason to develop and implement skill-sensitive training procedures, since the acquisition of domain-specific skills is critical for expert performance. As a consequence, training procedures might be essential for complex applications and/or unfamiliar device transformations.

Depth perception in virtual reality: distance estimations in peri- and extrapersonal space.

The present study investigated depth perception in virtual environments. Twenty-three participants verbally estimated ten distances between 40 cm and 500 cm in three different virtual environments in two conditions: (1) only one target was presented or (2) ten targets were presented at the same time. Additionally, the presence of a metric aid was varied. A questionnaire assessed subjective ratings about physical complaints (e.g., headache), the experience in the virtual world (e.g., presence), and the experiment itself (self-evaluation of the estimations). Results show that participants underestimate the virtual distances but are able to perceive the distances in the right metric order even when only very simple virtual environments are presented. Furthermore, interindividual differences and intraindividual stabilities can be found among participants, and neither the three different virtual environments nor the metric aid improved depth estimations. Estimation performance is better in peripersonal than in extrapersonal space. In contrast, subjective ratings provide a preferred space: a closed room with visible floor, ceiling, and walls.

Notebook input devices put to the age test: the usability of trackpoint and touchpad for middle-aged adults.

In two experiments, the usability of input devices integrated into computer notebooks was under study. The most common input devices, touchpad (experiment 1) and trackpoint (experiment 2) were examined. So far, the evaluation of mobile input devices has been restricted to younger users. However, due to ongoing demographic change, the main target group of mobile devices will be older users. Therefore, the present study focused on ageing effects. A total of 14 middle-aged (40-65 years) and 20 younger (20-32 years) users were compared regarding speed and accuracy of cursor control in a point-click and a point-drag-drop task. Moreover, the effects of training were addressed by examining the performance increase over time. In total, 640 trials per task and input device were executed. The results show that ageing is a central factor to be considered in input device design. Middle-aged users were significantly slower than younger users when executing the different tasks. Over time, a significant training effect was observed for both devices and both age groups, although the benefit of training was greater for the middle-aged group. Generally, the touchpad performance was higher than the trackpoint performance in both age groups, but the age-related performance decrements were less distinct when using the touchpad.

Carcinoma showing thymic-like elements--a rare malignancy of the thyroid gland.

BACKGROUND: Carcinoma showing thymic-like elements (CASTLE) is a rare tumour of the thyroid of thymic origin. The histological appearance of this tumour may be similar to that of squamous cell carcinoma of the thyroid, but outcome associated with CASTLE is more favourable. METHODS: A systematic literature review was conducted for case reports on CASTLE. A text word search of the Medline database was made with a manual search of the citations from these references. Twenty-two case reports were found. RESULTS: In five patients with tumour-negative lymph nodes no local or distant recurrence was observed. Seventeen patients had unknown or involved lymph nodes. Two patients were excluded from further study: one had no follow-up and one was treated by irradiation only. Of the remaining 15, six had local, three had distant and two had local and distant recurrence. In patients with involved or unknown lymph node status, local recurrence was noted in one of five patients treated by surgery and irradiation, and in seven of ten patients treated by surgery alone. Irradiation or systemic chemotherapy was given to four patients with recurrent tumours, with variable response. CONCLUSION: CASTLE with tumour-negative lymph nodes has a low risk of recurrence and surgery without adjuvant therapy is sufficient. Radiotherapy seems indicated when lymph nodes are tumour positive and can be effective for recurrent tumours. In selected patients surgery for recurrent tumour can improve quality of life and outcome.

Intra-abdominal sequestration of the lung and elevated serum levels of CA 19-9: a diagnostic pitfall.

BACKGROUND: Extralobar pulmonary sequestration is an uncommon congenital abnormality that is rarely diagnosed after the age of 40 years. We describe a 64-year-old woman with an intra-abdominal sequestration of the lung and elevated carbohydrate antigen (CA) 19-9 serum levels. CASE OUTLINE: On abdominal ultrasound a semi-solid cystic tumour was demonstrated that showed tight connection to the tail of the pancreas according to computed tomography. Cytological examination of the percutaneous biopsy did not lead to a definitive diagnosis. CA 19-9 serum levels were repeatedly elevated >250 IU/ml. With a tentative diagnosis of a tumour of the tail of pancreas the semi-solid cystic mass was resected. Frozen section histology suggested the diagnosis of pulmonary sequestration, which was confirmed by definitive histological examination. Immunohistochemical staining of the specimen with a specific monoclonal antibody against CA 19-9 showed strong immunoreactivity. Three months later the elevated CA 19-9 serum levels returned to normal. DISCUSSION: Elevated CA 19-9 serum levels have been described in benign pulmonary and mediastinal cystic lesions and in one case of extralobar intrathoracic lung sequestration. Although there is evidence that malignancies may arise in congenital lung cysts, CA 19-9 serum levels have not been investigated in such cases. Based on our results elevated serum values of CA 19-9 in combination with a cystic semi-solid mass in the left subphrenic space should include the differential diagnosis of extralobar pulmonary sequestration.

Association of microsomal epoxide hydrolase polymorphisms and lung cancer risk.

Microsomal epoxide hydrolase (mEH) plays a dual role in the detoxification and activation of tobacco procarcinogens. Two polymorphisms affecting enzyme activity have been described in the exons 3 and 4 of the mEH gene, which result in the substitution of amino acids histidine to tyrosine at residue 113, and arginine to histidine at residue 139, respectively. We performed a hospital-based case-control study consisting of 277 newly diagnosed lung cancer patients and 496 control subjects to investigate a possible association between these two polymorphisms and lung cancer risk. The polymorphisms were determined by polymerase chain reaction/restriction fragment length polymorphism and TaqMan assay using DNA from peripheral white blood cells. Logistic regression was performed to calculate odds ratios (ORs), confidence limits (CL) and to control for possible confounders. The exon 3 polymorphism of the mEH gene was associated with a significantly decreased risk of lung cancer. The adjusted OR, calculated relative to subjects with the Tyr113/Tyr113 wild type, for the His113/His113 genotype was 0.38 (95% CL 0.20-0.75). An analysis according to histological subtypes revealed a statistically significant association for adenocarcinomas; the adjusted OR for the His113/His113 genotype was 0.40 (95% CL 0.17-0.94). In contrast, no relationship between the exon 4 polymorphism and lung cancer risk was found. The adjusted OR, calculated relative to the His139/His139 wild type, was for the Arg139/Arg139 genotype 1.83 (0.76-4.44). Our results support the hypothesis that genetically reduced mEH activity may be protective against lung cancer.

Significant symptomatic relief after transoral endoscopic staple-assisted treatment of Zenker's diverticulum.

BACKGROUND: Zenker's diverticulum is associated with characteristic symptoms of progressive dysphagia and regurgitation. As most patients are elderly, the perioperative risk is usually high. We report our clinical experience with the transoral endoscopic staple-assisted method, including a thorough assessment of the symptomatic relief achieved by the procedure. METHODS: 46 consecutive patients (29 m, 17 f) with a median age of 61 years (range, 37-96 years) were treated between 1997 and 2002. The symptoms and their frequency were registered. The follow-up consisted of clinical and radiographic investigations. RESULTS: The median size of the diverticulum was 4 cm (range, 2-12 cm). Transoral treatment was successful in 39 patients; in 7 cases (15.2%) a switch to open surgery was required. The median operating time was 30 min (range, 10-150 min). Mortality rate was nil, while morbidity was 7.7%. The median duration of the postoperative hospital stay was 5 days (range, 1-65 days). After a median follow-up of 11 months (range, 1-40 months), 5 patients had been reoperated on endoscopically due to clinical recurrence. Clinical symptoms were significantly reduced (dysphagia of liquids p

Functional impairment of the abdominal wall following laparoscopic and open cholecystectomy.

BACKGROUND: Subcostal incisions for open cholecystectomy (OC) denervate the right upper and middle abdomen. METHODS: Sensory and abdominal muscle function (Janda's muscle function test, Cybex 6000) was evaluated. Healthy volunteers (10 women, 12 men) were compared with 13 women and 12 men after OC and 11 women and 11 men after laparoscopic cholecystectomy (LC). For computed tomography (CT) studies, a spiral scanner was used. RESULTS: Of the OC patients, 21 (95.5%) complained of dys- and anesthesias below the incision. Of the LC patients, only nine (2.4%) reported anesthesias around the port sites. Normal subjects scored significantly higher in muscle strength (p <.01). LC patients scored higher than OC patients at 10 degrees and 20 degrees trunk flexion (p <.05). Depending on the flexion angles, the men in all groups developed 30-114% more muscle power than the women. Denervation of the abdominal muscles was confirmed by CT. CONCLUSION: OC reduced skin sensitivity and abdominal muscle function. Although the procedure is minimally invasive, LC also causes sensory and functional losses, albeit minor ones.

Endothelial cell compatibility of azithromycin and erythromycin.

Phlebitis is a severe local adverse event related to the use of parenteral macrolides. In order to evaluate the effect of azithromycin and erythromycin on human venous endothelial cells, we set up an in vitro model. The intracellular levels of purine nucleotides, as adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP) and guanosine 5'-triphosphate (GTP), were measured by means of high-performance liquid chromatography. Incubation of cells with 2 mg/mL azithromycin and erythromycin resulted in a rapid decline of intracellular ATP from 12.5 +/- 0.9 nmol/million cells to 4.1 +/- 0.3 and 2.6 +/- 0.4 nmol/million cells, respectively, after 60 min. In addition, ADP was extensively depleted from 2.1 +/- 0.17 nmol/million cells to 0.8 +/- 0.09 and 0.8 +/- 0.13 nmol/million cells after 60 min. After exposure of 0.5 mg/mL azithromycin and erythromycin, no significant decline of intracellular high-energy phosphate levels occurred after 20 and 60 min. Based on these results, solutions of azithromycin and erythromycin may not be well tolerated and may cause local adverse reactions even if diluted according to the manufacturer's recommendation.

Video-assisted resection of pulsative midesophagus diverticula.

BACKGROUND: Pulsative diverticula located in the midesophagus occur rarely. Surgical treatment is indicated for symptomatic diverticula. This study evaluated a new minimally invasive method of treatment. METHODS: Three women, ages 69 to 73 years, underwent resections of diverticula via a thoracoscopic access. No major complications were observed. Preoperative symptoms such as dysphagia, regurgitation, aspiration, loss of weight, and retrosternal pain were not reported at follow-up assessment 3 to 60 months after surgery. The patients were highly satisfied with the functional results. CONCLUSIONS: According to our results, minimally invasive treatment of midesophagus diverticula by thoracoscopic resections may be performed with excellent outcome.

[Spontaneous perforation of the large intestine. Resection with primary anastomosis or staged (Hartmann) procedure?]. / Spontane Dickdarmperforation. Resektion mit primärer Anastomose oder Diskontinuitätsresektion (Hartmann)?

Whereas primary resection to remove the septic focus stands undisputed in the therapy of spontaneous perforation of the colon, there is still no consensus as to whether to perform a primary anastomosis or a staged procedure (Hartmann). Prospective randomized studies comparing both concepts are lacking. Obviously these two competing therapies fit different groups of patients whose diseases differ concerning etiology, localisation and severity. Analysis of the literature of the past few years defined some criteria that help to decide when to omit primary anastomosis: MPI > 20, APACHE II score > 15, preoperative organ insufficiency, Hinchey grade III or IV and ASA score IV. In these cases a discontinuity resection is recommended. Primary resection with anastomosis and Hartmann procedure are not competing operations but situation-dependent therapeutic concepts in spontaneous colonic perforation.

Successful treatment of severe respiratory papillomatosis with intravenous cidofovir and interferon alpha-2b.

In contrast to uncomplicated juvenile laryngeal papillomas which may regress spontaneously, papillomatosis involving pulmonary parenchyma is associated with a poor outcome. This report represents the case of a 34 yr-old female in whom respiratory papillomatosis resulted in voice problems and recurrent pneumonias due to bronchial obstruction. A computed tomographic scan of the chest showed worsening bilateral round cavitating consolidations. Bronchoscopy revealed polypoid lesions of the right vocal cord and the midtrachea which were confirmed as squamous papillomatosis by histology. Interferon (IFN)alpha-2b treatment was inefficient as was cidofovir monotherapy on a maintenance basis. Six months of IFN-alpha-2b and cidofovir in combination led to a complete macroscopic disappearance of the laryngeal lesions and to an impressive regression of the tracheal papillomas and of the intrapulmonary consolidations. These data provide support that severe respiratory papillomatosis can be safely treated by interferon alpha-2b and cidofovir in combination. Probably the same mechanisms as in ribavirin plus interferon alpha-2b, in the treatment of patients with chronic hepatitis C, are responsible for the therapeutic success in this case.

Fecal excretion of calprotectin in colorectal cancer: relationship to tumor characteristics.

BACKGROUND: The aim of this study was to evaluate fecal calprotectin in patients treated for colorectal cancer. Furthermore, the changes in fecal calprotectin concentration from before to after surgery were investigated. METHODS: In 155 patients with newly diagnosed colorectal cancer, two spot samples were taken from the same feces on two consecutive days. RESULTS: Three ways of evaluating calprotectin excretion were compared, (1st spot 1st stool; maximum of 1st spot 1st stool and 2nd spot 1st stool; maximum of 1st spot 1st stool and 1st spot 2nd stool) and gave similar results with median fecal calprotectin values 47 mg/l, 52 mg/l and 54 mg/l, respectively. Median calprotectin concentration did not differ significantly between different tumor stages, although the levels were slightly lower in Dukes stage A tumor than in the rest of the stages. Neither were there any differences in the concentrations related to the localization, size or the histological grading of the carcinoma. As the currently used cut-off level for fecal calprotectin is 10 mg/l, 87% of all patients had elevated fecal calprotectin. Seventy-nine percent of the patients had levels above 15 mg/l and 74% had levels above 20 mg/l (1st spot 1st stool). In patients who delivered fecal samples after the operation the calprotectin value fell significantly from a preoperative median value of 45 mg/l to 14 mg/l after the resection. CONCLUSIONS: The majority of patients with colorectal cancer have increased fecal concentration of calprotectin. One single fecal spot seems to be sufficient for determination of the calprotectin level. Measurement of fecal calprotectin may possibly become of value as a marker for colorectal cancer, although calprotectin, similar to fecal occult blood (FOB) tests, is a non-specific test for colorectal pathology, also being elevated in inflammatory bowel diseases. Further investigation of its specificity is therefore needed.

Intracellular concentration of the HIV protease inhibitors indinavir and saquinavir in human endothelial cells.

Human vascular endothelial cells may serve as targets and a reservoir for human immunodeficiency virus type 1 (HIV-1). The antiviral activity of HIV protease inhibitors is reported to be related directly to the intracellular amount of the drug. To assess intracellular concentrations of two HIV protease inhibitors, human umbilical venous endothelial cells (HUVECs) were exposed for 3 h and 24 h to 100, 10 and 1 mg/L indinavir and saquinavir. Intracellular drug concentrations and the total drug amount in the supernatant were measured by means of high-performance liquid chromatography (HPLC). Exposure of HUVECs to 10 and 1 mg/L indinavir and saquinavir resulted in undetectable intracellular drug levels in 6 x 10(5) cells/well. Incubation of cells with solutions of 100 mg/L indinavir and saquinavir led to mean intracellular concentrations of indinavir (132 +/- 56 mg/L after 3 h and 150 +/- 29 mg/L after 24 h, respectively) and of saquinavir (96 +/- 10 mg/L after 3 h and 100 +/- 5 mg/L after 24 h) that were comparable to the levels determined for the substances in the supernatant over time (P > 0.001). These data indicate that intracellular concentrations of indinavir and saquinavir correlate well with the extracellular levels. Consequently, measurements of drug concentrations in patient's plasma by HPLC are assumed to be a good means of monitoring the intracellular drug concentration.

Gender-specific differences in the natural history, clinical features, and socioeconomic status of HIV-infected patients: experience of a treatment centre in Vienna.

BACKGROUND: In order to evaluate natural history, clinical features, and socioeconomic aspects in HIV-infected women, a prospective study comprising 695 HIV-infected patients was performed at our department. METHODS: Demographic data, CD4+ T-lymphocyte counts, human immunodeficiency virus-1 (HIV-1) plasma loads, AIDS indicator diseases and socioeconomic variables were recorded. Prognostic factors for survival were evaluated by univariate and multivariate analysis. Data of men and women were compared. RESULTS: The mean age of the 150 women (29.4 +/- 9.4 years) was significantly lower than that of men (32.6 +/- 9.7 years, p = 0.0002). CD4+ T-lymphocyte counts, HIV1-plasma loads, and AIDS indicator diseases did not significantly differ between men and women; the same was true for all socioeconomic variables (family status, education, professional training, employment status) except family status. No significant difference in median overall and AIDS-free survival was observed between females (2033 and 1593 days) and males (1554.5 and 1235 days, respectively, p = 0.36 and p = 0.098). Overall survival compared by age groups (< 30, 31-50, > 50 years), by risk categories (homosexuals, i.v. drug users, heterosexual contacts) and by CD4+ T-lymphocyte count (< 200, 200-500, > 500 cells/mm3), differed significantly (p < 0.001) as did AIDS-free survival. Lower age and a high CD4+ T-lymphocyte count were independently associated with the outcome in the multivariate analysis. (Overall survival/relative risk: 0.49 for age < 30 years and 2.3 for CD4+ T-lymphocyte count < 200 cells/mm3, AIDS-free survival/relative risk: 0.65 for age < 30 years and 3.3 for CD4+ T-lymphocyte count < 200 cells/mm3). HIV-1 plasma loads as a prognostic factor could not be evaluated due to the small number of patients who died or developed AIDS (2/375 and 10/375 patients, respectively). CONCLUSION: Our results showed no difference in the natural history and clinical features of HIV infection between men and women. However, pulmonary tuberculosis was associated with a significantly longer survival compared to other AIDS-defining diseases. Lower age and high CD4+ T-lymphocyte count are independent predictors for survival. With the exception of family status, socioeconomic variables showed no differences between male and female patients.

Reconstructive intestinal surgery after open management of severe intraabdominal infection.

Open management (OM) of severe intraabdominal infection often is complicated by fistula formation and the need for complex reconstructive procedures. From 1988 to 1998 a series of 145 patients were treated by OM. Of these patients, 24 developed intestinal fistulas and 42 had to be treated by discontinuity resections prior to OM for intestinal perforations or anastomotic insufficiency. Of the patients with fistulas or enterostomies, 61% survived. Reconstructive surgery was performed after infections had completely subsided. Patients were examined on follow-up, and the quality of life was assessed by 36-item short-form health survey questionnaires. Restorative surgery was performed in 32 of 40 patients 102 days (median) after beginning OM. All patients survived. Anastomotic leakage developed in six patients (18%). Thirty patients (94%) were followed up; 70% indicated their quality of life to be good. Despite a higher rate of anastomotic problems than with elective visceral operations, reconstructive intestinal surgery after OM may be performed without mortality and satisfying long-term outcome.

Endothelial cell compatibility of trovafloxacin and levofloxacin for intravenous use.

Levofloxacin and trovafloxacin have excellent activity against a variety of Gram-positive and Gram-negative organisms resistant to the established agents. One local side-effect closely related to the use of parenteral fluoroquinolones is phlebitis. To evaluate the effect of trovafloxacin and levofloxacin on endothelial cell viability, intracellular levels of adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), guanosine 5'-triphosphate (GTP) and guanosine 5'-diphosphate (GDP) levels were measured using high-performance liquid chromatography. Trovafloxacin at concentrations of 2 and 1 mg/mL reduced the intracellular ATP content from 12.5 +/- 1.7 to 1.9 +/- 0.3 nmol/10(6) cells and 9.3 +/- 0.8 nmol/10(6) cells, respectively, within 60 min. In addition, ADP, GTP and GDP levels were extensively depleted. Levofloxacin at concentrations of 5 and 2.5 mg/mL led to a significant ATP decline from 12.5 +/- 1.7 to 2.3 +/- 0.2 nmol/10(6) cells and 10.3 +/- 0.9 nmol/10(6) cells, respectively, within 60 min. These data indicate that infusions of high doses of trovafloxacin or levofloxacin are not compatible with maintenance of endothelial cell function. Commercial preparations have to be diluted and should be administered into large veins.

A simple method to quantify staphylococcal protein A in the presence of human or animal IgG in various samples.

Immunoassays designed to measure low concentrations of staphylococcal protein A (SPA) that have been leached into antibody preparations intended for therapeutic use are subject to differing degrees of interference. Methods established to quantify SPA in murine antibody preparations are not accurate in the presence of human or humanized IgG. We report the development of an enzyme-linked immunosorbent assay (ELISA) for SPA with a detection limit of 7 pg/ml and the optimization of a method that permits complete dissociation of SPA-immunoglobulin-complexes. This assay is a modification of our heat-mediated dissociation (HD-SD) treatment with sodium dodecyl sulfate (SDS) and diethylenetriaminepentacetic acid (DTPA) for total immune-complex dissociation, in which the heat treatment has been prolonged and the diluent is characterized by increased protein content and buffering capacity. The diluent developed contains SDS, DTPA and bovine serum albumin dissolved in a 0.1 M phosphate buffer (pH 7.2). To validate the efficiency of this novel method, a series of samples have been assayed, including samples reconstituted in vitro, samples of purified antibodies, and plasma from patients. The described method has been shown to be generally efficient in quantitating all native and recombinant SPA in samples containing up to 50 mg/ml of human IgG. These data demonstrate the utility of this technique in determining SPA contamination of recombinant immunoglobulin therapeutic products.