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Video-assisted thoracoscopic surgery--indications, results, complications, and contraindications.

In recent times minimally invasive surgery has secured a firm place among the therapeutic options in thoracic surgery. The experience and results gained from video-assisted surgery on 109 patients between January 1, 1992 and July 31, 1993 are critically discussed. The procedure could be completed thoracoscopically on 94 of them. A change of method was necessary nine times for technical reasons and six times for oncological reasons (two times due to metastasis, four times due to bronchial carcinoma). A total of 154 individual operations were conducted. Sixty-three patients with recurrent spontaneous pneumothorax were successfully treated. The relapse rate was 1.5%. With the exception of three rethoracotomies (one due to postoperative hemorrhaging and two to persistent fistula) no significant complications occurred. Further indications included capsulated pleural empyema (n = 1), persistent hematothorax (n = 2), pleurectomy for malignant pleural effusion (n = 2), pleural tumors (n = 3), pulmonary parenchyma (n = 2), interstitial lung diseases (n = 3), bullous emphysema (n = 2), peripheral lung nodules (n = 18), mediastinal tumors (n = 8), and sympathectomy (n = 2). The advantages of video-assisted thoracoscopic surgery for patients include cosmetic considerations, low pain, earlier postoperative mobilization, and for some indications, a shorter operation period. The significant disadvantages for the surgeon are the loss of binocular vision as well as the impossibility of intraoperative palpation.

Bronchial Neoplasms↗

[Complicated intestinal tuberculosis of the mesenteric root].

HISTORY AND CLINICAL FINDINGS: In the course of 2 1/2 years a 72-year-old man had five episodes of intestinal bleeding with anaemia, but no cause was at first found by routine diagnostic tests. After the fourth episode a diagnostic laparotomy was performed at which a diffusely infiltrating growing tumour was found. As it encircled the mesenteric vascular axis resection was not possible. But because of threatened ileal obstruction by the tumour a segmental ileal resection was performed, but no intraoperative diagnosis could be established. INVESTIGATIONS: Repeated oesophago-gastro-duodenoscopies and a coloscopy all revealed blood, especially in the upper gastrointestinal tract, but no bleeding source was found. Angiography suggested bleeding in the terminal ileum. Computed tomography demonstrated a tumour in the region of the mesenteric root. DIAGNOSIS, TREATMENT AND COURSE: At a second laparotomy because of another bleeding, which required a blood transfusion, tuberculosis was diagnosed. Triple drug treatment was initiated and the patient has been free of symptoms and bleedings since then and fully active for 1 1/2 years. CONCLUSION: This case clearly demonstrates the difficulty of diagnosis and the long delay until specific treatment, because the combination of "tumour", bleeding and stenosis of the small intestine by an infiltrative lesion at first pointed to malignant process.

Aged↗

Validation of cardiologists' decisions to initiate reperfusion therapy for acute myocardial infarction with electrocardiograms viewed on liquid crystal displays of cellular telephones.

BACKGROUND: The transmission of 12-lead electrocardiograms from remote locations to hand-held computers of cardiologists is now possible with the development of wireless technology and computer software. This investigation determined whether the cardiologist's decisions regarding reperfusion therapy for patients with symptoms suggestive of an acute myocardial infarction are the same when given electrocardiograms displayed on a cellular telephone as on a standard paper recording. METHODS: Cardiologists were given 20 electrocardiograms of patients with acute chest pain suggestive of acute myocardial infarction to test the diagnostic reliability of the Nokia 9000i cellular telephone liquid crystal display (LCD) screen. The cardiologists made their decision to initiate or not initiate reperfusion therapy for the patients after viewing their electrocardiograms displayed on both 5-mm and 1-mm formatted grids and twice on traditional printout electrocardiograms. The control level of intraobserver agreement between the responses from the 2 sets of paper display electrocardiograms was compared with the experimental level of intraobserver agreement between the 1-mm LCD electrocardiograms and both sets of paper display electrocardiograms to determine whether the viewing medium affected the cardiologist's decisions. The 1-mm and 5-mm LCD screen electrocardiograms were compared to determine if the grid size affected the cardiologist's decisions. RESULTS: Ninety-three percent of the 2 sets of paper-guided decisions were in agreement. When comparing the 1-mm LCD-guided decisions with both sets of paper-guided decisions, 94% and 89% of the decisions, respectively, were in agreement. The differences between the control and experimental degrees of intraobserver agreement of 1% and 4% were not statistically significant (P1 =.81, P2 =.29). Ninety-one percent of the 1-mm LCD-guided decisions were in agreement with the 5-mm LCD-guided decisions. CONCLUSIONS: Cardiologists' decisions did not vary significantly when viewing either traditional paper electrocardiograms or LCD screen electrocardiograms. Even though there was not a significant difference in the cardiologists' decisions when they viewed electrocardiograms displayed on both the 1-mm and 5-mm grid, it is recommended that the 1-mm grid be used for clinical implementation of the LCD screen.

Computer Terminals↗

An experimental solution for the Luria-Delbrück fluctuation problem in measuring hypermutation rates.

A cell line harboring all trans-acting elements necessary for hypermutation was transfected with a plasmid harboring the major cis-acting elements plus a green fluorescent protein gene containing a premature chain-termination codon. Transfected cells do not fluoresce unless the stop codon reverts. When a sizable cell population is purged of revertants by sorting, the frequency of mutants increases linearly with time, and there is no Luria-Delbrück fluctuation effect. Moreover, as mutant frequencies seemed to vary less than cell numbers in replicate cultures, it is suggested that hypermutation might not be coupled closely to cell division.

Cell Line, Transformed↗

The LHbeta gene of several mammals embeds a carboxyl-terminal peptide-like sequence revealing a critical role for mucin oligosaccharides in the evolution of lutropin to chorionic gonadotropin in the animal phyla.

The expression of a previously untranslated carboxylterminal sequence is associated with the ancestral lutropin (LH) beta to the beta-subunit gene evolution of choriogonadotropins (CG). The peptide extension (denoted as CTP) is rich in mucin-type O-glycans and confers new hormonal properties on CG relative to the LH. Although the LHbeta gene is conserved among mammals and only a few frameshift mutations account for the extension, it is merely seen in primates and equids. Bioinformatics identified a CTP-like sequence that is encrypted in the LHbeta gene of several mammalian species but not in birds, amphibians, or fish. We then examined whether or not decoding of the cryptic CTP in the bovine LHbeta gene (boCTP) would be sufficient to generate the LHbeta species of a ruminant with properties typical to the CGbeta subunit. The mutated bovine LHbeta-boCTP subunit was expressed and N-glycosylated in transfected Chinese hamster ovary cells. However, unlike human (h) CGbeta CTP, the cryptic boCTP was devoid of mucin O-glycans. This deficiency was further confirmed when the boCTP domain was substituted for the natural CTP in the human CGbeta subunit. Moreover, when expressed in polarized Madin-Darby canine kidney cells, this hCGbeta-boCTP chimera was secreted basolaterally rather than from the apical compartment, which is the route of the wild type hCGbeta subunit, a sorting function attributed to the O-glycans attached to the CTP. This result shows that the cryptic peptide does not orientate CG to the apical face of the placenta, to the maternal circulation as seen in primates. The absence of this function, which distinguishes CG from LH, provides an explanation as to why the LHbeta to CGbeta evolution did not occur in ruminants. We propose that in primates and equids, further natural mutations in the progenitor LHbeta gene resulted in the efficient O-glycosylation of the CTP, thus favoring the retention of an elongated reading frame.

Amino Acid Sequence↗

Patients with visual display unit-related facial symptoms are stingers.

Thirty patients without obvious skin disease but with subjective skin symptoms related to work with visual display units (VDUs) and 32 healthy persons were single-blind-tested with a solution of 5% lactic acid and pure water on their cheeks. Thirteen of the patients and 6 control persons reacted positively as "stingers" (p < 0.05) in this objective test of sensitive skin. The reason why some patients react with subjective symptoms like itching, burning, stinging, prickling or tingling is unclear. The result of this study, that patients with VDU-related skin symptoms have sensitive skin, does not tell anything about the aetiology of the symptoms. Former studies speak against the role of electric and magnetic fields and indicate that "techno-stress", cognitive factors or flickering from the VDUs or fluorescent tubes could be of importance, as could the Swedish mass media debate.

Adult↗

Odontologic survey of referred patients with symptoms allegedly caused by electricity or visual display units.

Twenty-eight consecutive patients with symptoms allegedly caused by electricity or visual display units were odontologically investigated according to a specially designed registration form including an anamnestic interview and a clinical protocol. The most common oral and general symptoms reported were burning mouth, craniomandibular dysfunction symptoms, skin complaints, and fatigue. Oral symptoms such as craniomandibular dysfunction and general symptoms such as eye complaints and dizziness scored highest on a visual analog scale regarding mean symptom intensity. The patients reported various numbers of medical diagnoses, such as allergic rhinitis or asthma and hypothyroidism. Various dental diseases were found; the most common were temporomandibular joint and masticatory muscle dysfunctions, lesions in the oral mucosa, and periodontal diseases. Urinary-Hg (U-Hg) analysis showed a mean U-Hg concentration of 8.5 nmol Hg/L urine, and none of the patients exceeded the limit of 50 nmol Hg/L urine. The U-Hg concentration was positively correlated with the number of amalgam fillings (P< 0.01) and craniomandibular disorders (P < 0.05). No or low secretion of the minor mucous glands was found in 43% of the patients. One patient showed hypersensitivity to gold and cobalt. The present study showed that various odontologic factors might be involved in some of these patients' suffering. Thus, it is important that professionals from other disciplines collaborate with dentistry if these patients are to be properly investigated.

Adult↗

A field study of supplementary rest breaks for data-entry operators.

This study examined the effects of supplementary rest breaks on musculoskeletal discomfort, eyestrain, mood, and performance in data-entry workers. Two rest break schedules were compared in a within-subjects design. Workers alternated between a 'conventional' and a 'supplementary' schedule in 4-week intervals. The conventional schedule contained a 15-min break during the first half of the work shift and a 15-min break during the second half of the shift. The supplementary schedule contained the same two 15-min breaks, and a 5-min break during each hour which otherwise did not contain a break, for a total of 20 extra minutes of break time. Results are based on data from 42 workers. They indicated that discomfort in several areas of the body, and eyestrain, were significantly lower under the supplementary than under the conventional schedule. While symptoms increased from pre- to post-work periods under both schedules, the magnitude of the increases was significantly less under the supplementary schedule. In addition, increases in discomfort of the right forearm, wrist and hand over the course of the work week under the conventional schedule were eliminated under the supplementary schedule. These beneficial effects were obtained without reductions in data-entry performance.

Adult↗

Pointing movement visually controlled through a video display: adaptation to scale change.

This study concerns the adaptation of motor system when the production of movement was visually controlled through a video display. The subjects had to perform a pointing movement in two visual-feedback conditions: they could see the displacement of their hand or only the final location of the hand on the videoscreen. By changing the zoom of the camera, the amplitude of the movement perceived on the screen was increased, decreased or held equal to the actual movement. Results showed that the movement adapted quickly to the apparent distance changes. In the full visual-feedback condition, the adaptation was smaller in magnitude than in the partial visual-feedback condition. Even though the actual movement was always the same, the subjects thought they carried out different movements. Therefore, the subjects did not use kinematic information provided by the kinaesthetic system but essentially visual information furnished by the video-screen. Taken together, these results show that adaptation to scale changes does not allow the achievement of the perception of a single working space but seems rather specific to each scale.

Adaptation, Physiological↗

Posture, discomfort and performance in a VDT task.

Improvements in workplace, working posture, and discomfort need to be justified in terms of improvements in performance. Previously, a visual inspection task has been investigated. The objective of the current study was to demonstrate the interactions between workplace, work duration, discomfort, working posture, as well as performance in a 2-h typing task. Three levels of keyboard heights were used to change working posture (e.g. joint angles and postural shifts), and thus presumably discomfort (e.g. rating of perceived discomfort and body part discomfort), and performance (e.g. typing speed, error rate and error correction rate). The results indicated that the hypothesized posture-comfort-performance interrelationships were partially supported. Keyboard height had effects on working posture adopted. As in previous studies, the rate of postural shift was a good indication of discomfort in a VDT task. Discomfort and postural shift rate had adverse effects on performance (e.g. error rate). However, these effects on error rate may not be strong.

Adult↗

Muscle activity and cardiovascular response during computer-mouse work with and without memory demands.

Computer-mouse work is characterized by repetitive movements combined with mental demands. The present purpose was to study how the body responded to simulated Computer Aided Design (CAD) work without memory demand and when a high short-term memory demand was introduced. Nine female subjects repetitively performed a task which involved 15 s of elevation of the right index and middle fingers followed by 6 s of rest. Every second time the fingers rested, the left index finger was required to type a six-figure number, either '123456' (without memory demand) or a random number shown half a minute before (with memory demand). After 7 min of performing the task without memory demand, the memory demand was introduced and continued for 1 h. Introduction of memory demand resulted in increased heart rate (77-->84 beats/min), blood pressure (systolic 129-->140 mmHg; diastolic 72-->79 mmHg) and forearm extensor muscle activity (wrist, 2.7-->4.5% EMGmax; finger, 5.6-->7.5% EMGmax) and finger flexor muscle activity (0.7-->1.2% EMGmax) indicating increased co-contraction. Hereafter, muscle activity and cardiovascular response tended to decrease. Self-reported stress and rating of perceived exertion (RPE) for the right shoulder increased throughout the period. Two additional sub-studies were inlcuded, which focused on adaptation to the physical load, showing a decrease in muscle activity and arousal, and reintroduction of the memory load, showing a lower response as compared to the initial response. The practical consequences of the findings suggest that job content should have variable mental demands.

Adult↗

Observation distance and blinking rate measurement during on-site investigation: new electronic equipment.

Modern work activities often require an intense and prolonged visual effort on near objects. At the same time, occupational asthenopia caused by accommodation and binocularity overloading is a very common complaint in these working populations. Moreover, blinking rate seems to be a sensitive parameter with 'indoor-near-work operators', possibly increased by both chemical and physical environmental agents and decreased by cognitive effort. In this paper, a new piece of electronic equipment used to measure the observation distance and blinking rate is described.

Air Pollution, Indoor↗

A maritime navigation display that provides visual feedback to improve conning officers' ship-handling during low visibility environments.

Navigating a ship at night in close proximity to another vessel is a dangerous task. To improve conning officers' night time ship-handling performance, a visual navigation display is proposed that is mounted on the stern of the aircraft carrier that will help shipboard conning officers manoeuvre in a battle group formation. To test the effectiveness of the visual navigation display, the Nimitz-class aircraft and plane guard vessel, a Ticonderoga-class cruiser, were modelled in a virtual environment. A navigation display condition had significantly fewer navigational positional errors than a non-navigation display condition. The navigation display provided immediate feedback as to whether the aircraft carrier had changed bearing or speed, thus enabling the operator to initiate the appropriate input to maintain station astern of the carrier. Actual or potential applications of this research include the deployment of a maritime navigation display to assist conning officers' ship handling.

Computer Graphics↗

The impact of working technique on physical loads - an exposure profile among newspaper editors.

The aim of this study was to investigate the possible associations between working technique, sex, symptoms and level of physical load in VDU-work. A study group of 32 employees in the editing department of a daily newspaper answered a questionnaire, about physical working conditions and symptoms from the neck and the upper extremities. Muscular load, wrist positions and computer mouse forces were measured. Working technique was assessed from an observation protocol for computer work. In addition ratings of perceived exertion and overall comfort were collected. The results showed that subjects classified as having a good working technique worked with less muscular load in the forearm (extensor carpi ulnaris p=0.03) and in the trapezius muscle on the mouse operating side (p=0.02) compared to subjects classified as having a poor working technique. Moreover there were no differences in gap frequency (number of episodes when muscle activity is below 2.5% of a reference contraction) or muscular rest (total duration of gaps) between the two working technique groups. Women in this study used more force (mean force p=0.006, peak force p=0.02) expressed as % MVC than the men when operating the computer mouse. No major differences were shown in muscular load, wrist postures, perceived exertion or perceived comfort between men and women or between cases and symptom free subjects. In conclusion a good working technique was associated with reduced muscular load in the forearm muscles and in the trapezius muscle on the mouse operating side. Moreover women used more force (mean force and peak force) than men when operating the click button (left button) of the computer mouse.

Adult↗

Applying image descriptors to the assessment of legibility in Chinese characters.

The current study derived seven descriptors from the pixel matrix of 5401 Chinese characters in the commonly used Ming, Kai, Li, and Hei fonts. A factor analysis was used to reduce the number of descriptors for a validation experiment. The three-factor solution (number of strokes, character height, and character width) explaining 89.54% of the variance was derived from 5401 characters in four fonts. A 4 x 2 x 2 x 2 factorial experiment using fonts, number of strokes, character height, and character width as the independent variables was conducted to evaluate the impact of each critical factor on the legibility of Chinese characters. Each tested character was chosen from the 500 most commonly used characters to minimize the effect of familiarity and ensure that all participants could recognize the character if it was legible. The 16 university students who participated in the experiment were asked to identify a Chinese character initially displayed on a PC screen at its minimum size and enlarged gradually until the participant could recognize it. The analysis of variance suggests that all the main effects of font, number of strokes, character height, and character width are significant. The legibility thresholds of the four type styles from the most to the least legible are in the Hei, Ming, Kai, and Li sequence. Number of strokes is the only significant factor in predicting the legibility threshold for each individual font. However, if predicting the legibility threshold across four fonts, character height is the other significant factor with about the same predictive power as number of strokes. The legible threshold is increased by the number of strokes and decreased by the character height and character width.

Adult↗

No evidence for prolonged latency of saccadic eye movements due to intermittent light of a CRT computer screen.

Despite previous studies it remains unclear, whether saccadic eye movements across computer screens may be adversely affected by the intermittency of light of cathode ray tubes (CRT). We measured the latency of simple saccades to peripheral targets presented on a CRT-screen, operated at refresh rates of 50, 100 and 150 Hz, compared with a special fluorescent lamp display (FLD). Our results suggest that the intermittent light of CRT screens does not prolong the latency of saccades not even relative to a control condition of unmodulated steady light at the FLD. Further, there was no evidence for any individual effect in possibly susceptible subjects, e.g. at high critical flicker frequencies (CFF).

Adult↗

Standing at a kiosk: effects of key size and spacing on touch screen numeric keypad performance and user preference.

Touch screen input keys compete with other information for limited screen space. The present study estimated the smallest key size that would not degrade performance or user satisfaction. Twenty participants used finger touches to enter one, four or 10 digits in a numeric keypad displayed on a capacitive touch screen, while standing in front of a touch screen kiosk. Key size (10, 15, 20, 25 mm square) and edge-to-edge key spacing (1, 3 mm) were factorially combined. Performance was evaluated with response time and errors, and user preferences were obtained. Spacing had no measurable effects. Entry times were longer and errors were higher for smaller key sizes, but no significant differences were found between key sizes of 20 and 25 mm. Participants also preferred 20 mm keys to smaller keys, and they were indifferent between 20 and 25 mm keys. Therefore, a key size of 20 mm was found to be sufficiently large for land-on key entry.

Adolescent↗