Biomedical subjects

M Menozzi

Publications and source records attributed to M Menozzi.

At least 19 recordsLinked to original sources

PubMed2004

Information access at the point of care: what can we learn for designing a mobile CPR system?

OBJECTIVES: Hospitals have started to migrate their paper-based records to computerized patient records (CPR). The majority of today's CPR systems are stationary, which means that physicians use a clinical workstation to access CPR information. But health care professionals need to request and enter information at different locations, for example, on their daily ward round. This suggests the use of mobile computers, enabling an ubiquitous access to needed data. Different studies show that health care professionals are reluctant to use poorly designed mobile CPR systems, as the work at the point of care is very time-pressured and hectic. To design a system with high acceptance, it is essential to obtain empirical insight into the work practices and context in which the mobile CPR system will be used. METHOD: We investigated the physicians' work with the patient record during their daily round. With the help of a compact notation method, the physicians' interaction with the information system was recorded in real time. Fourteen physicians from three different departments (internal medicine, surgery, and geriatrics) of a middle-sized Swiss hospital participated in our study. RESULTS: Physicians have clear access preferences when they interact with the patient record during their daily round. There exists a clear profile of access frequencies and patterns, respectively. As an example, approximately 50% of all patient record accesses concern information about medications, vital signs and lab test results. DISCUSSION/CONCLUSION: A CPR system which is designed to reflect the access frequencies and patterns should improve the efficiency of data entry and retrieval and thus result in a system with high acceptance among physicians in the demanding environment during hospital rounds.

Access to Information↗

PubMed2003

Evaluation of two algorithms for counting forward saccades in a reading task.

We compared two algorithms, which are used to assess the number of forward saccades in a reading task from records of eye movements. In one algorithm saccades are detected analysing the velocity of eye movements. The third derivate of eye position in time (jerk) is used in the second algorithm for the detection of saccades. Both algorithms were applied on the same set of data, recorded using 24 subjects reading a German text, which was presented on two different displays. Our subjects read the text at a mean reading speed of 258.5 word/min. Both algorithms were found to produce a similar rate of artefacts in the number of detected saccades (2.5%), provided the threshold for detection (velocity or jerk) is set at an appropriate level and the same level of threshold is applied to all data. In both algorithms, the rate of artefacts increases with increasing distance of the threshold from its optimum. Inter-individual variation of the rate of artefacts increases more pronounced in the algorithm based on jerks. Eye blinks were identified as a major source of artefacts. A remedy is proposed, by means of which the rate of artefacts can be reduced.

Adult↗

PubMed2001

[Virtual retinal display system with nodal point image of a laser beam: construction example and evaluation of subjective brightness perception].

We investigated the perception of brightness for red monochromatic laser light. For this purpose, a modified virtual retinal display (VRD) was constructed. The modification involved projecting the laser beam into the eye. In our VRD, the laser beam pivots in the nodal point of the eye (badal system). The displayed image therefore does not depend on the refractive state of the eye. Brightness perception was assessed by means of psychophysical experiments. The results of these experiments indicate that perception of brightness at 652 nm increases more rapidly with increasing physical stimulus than does the perception of white light (colour temperature 2'935 K). At a wavelength of 652 nm, an optical power of 79 nW is required to produce an image subtending 2 degrees of equal brightness, as is perceived with an image of about 2'900 cd/m2 subtending 2 degrees.

Adult↗

PubMed2001

[Technical realization of an LCD-based vision test device].

We describe a computer-aided self-test vision screener for testing near and far visual acuity. The device generates images separately for each eye on a LCD. Acuity can be measured in the range between 0.1 and 1.6 for any distance between 0.34 m and 6 m. In addition, it also enables testing for colour deficiency, phoria, stereopsis and contrast sensitivity. The device is fully automatic and enables self-testing of the above mentioned functions. Initial practical application in an industrial environment has demonstrated the practicability of the device.

Diagnosis, Computer-Assisted↗

PubMed1998

[Effects of presbyopia on clinical phoria].

BACKGROUND: Due to accommodation-vergence cross-link we can expect that presbyopia will affect vergence as well. From investigations of cross-link as function of age one may assess strain of visual system due to presbyopia. Furthermore, this observation will give hints on innervation of ciliary muscle. MATERIAL AND METHOD: Vergence is assessed as function of stimulus of accommodation in 27 subjects (24-65 years). RESULTS: Presbyops tend to be exophoric for near vision. Vergence is linked to accommodation by means of a quadratic polynome rather than by a linear function. CONCLUSIONS: We may expect, that missing vergence strains visual system of presbyops. Results support Hess-Gullstrand theory of presbyopia and indicate a loss of innervation of ciliary muscle with increasing age.

Accommodation, Ocular↗

PubMed1998

[Computer-based determination of stereopsis].

AIM: A computer-based approach to assess stereopsis for screening purposes is described. This approach is based on random-dot stereograms (RDS). METHOD: The TNO test is a common method to assess stereopsis based on red/green anaglyphs and the use of RDS. This technique was transferred to a computer-based platform. To investigate the validity of the computer-based approach, 25 subjects were tested with both the TNO test and the computer-based approach. RESULTS: With regard to the spectral emission of the monitor screen, accurate separation of red and green for RDS generation was not possible. However, adaptation of the RDS to the colour filters used permitted the best-possible separation. The resolution of the monitor required a viewing distance of 2 m. The results obtained showed no significant differences between the two methods. CONCLUSIONS: For the computer-based screening, RDS and anaglyphs can be employed. The influence of the spectral emission of the monitor screen and its resolution can be reduced by adapting the RDS colours to the filters used and modifying the viewing distance.

Depth Perception↗

PubMed1998

[Computer-based determination of red/green color vision defects].

A commonly used method of investigating colour vision, that is, the ability of the human visual system to discriminate colours, is based on the use of isochromatic colour plates, such as those used in the Ishihara test. The present paper describes a new computer-based method of determining red/green colour vision deficiencies. The method involves the presentation of Ishihara colour plates on a computer monitor. It has been verified experimentally that, despite the differences between the spectral emission of the computer screen and the daylight reflected by the Ishihara plates, the method is capable of distinguishing between subjects with from those without colour vision deficiencies. For screening purposes, the use of a reduced number of plates is suggested. This suggestion makes use of nine instead of 14 plates, and the criterion of two incorrectly recognized plates to determine a colour vision deficiency.

Adult↗

PubMed1997

[Microfluctuations in accommodation].

BACKGROUND: So called microfluctuations of the power of crystalline lens are uncontested in scientific community. However, there are still open questions about possible artefacts which deserve discussion. PURPOSE: This contribution is intended to reopen discussion of matters concerning fundamentals about microfluctuations of the crystalline lens. METHOD AND RESULTS: Thoughts are outlined which render characteristics or even existence of microfluctuations questionable. CONCLUSION: There is still a need for a conclusive experiment to determine existence and role of microfluctuations.

Accommodation, Ocular↗

PubMed1997

[Computer-based assessment of visual acuity--technical realization].

Testing of visual acuity for distant vision can be computerized by using monitor screens to present optotypes. Because of the limited spatial resolution of conventional monitors, measurement of visual acuity for near vision is not possible. This paper describes a new computer-aided method for the measurement of both near and distant visual acuity. Our approach to the assessment of visual acuity for near vision is based on a recently developed liquid crystal display (a screen, LCD) measuring 10.5 mm x 15 mm. The LCD permits the presentation of optotypes for the measurement of visual acuity between 0.063 and 1.25 at a viewing distance of 40 cm (near/distant). The presentation of optotypes for the assessment of the acuity of distant vision uses a standard 17" monitor that permits visual acuity figures of between 0.032 and 1.6 to be assessed.

Diagnosis, Computer-Assisted↗

PubMed1996

[The suitability of various cephalometric planes for the determination of vertical alignment of the head].

Different cephalometric lines or planes may be used to determine vertical head tilt. 94 subjects were used to assess the difference in inclination between the Frankfurt horizontal and Reid's line by means of a photographic method. We found that the inclination of Reid's line differs about 13 degrees from the inclination of the Frankfurt horizontal and depends on the subject's sex but not on their age. Hand held inclinometer are used in most studies for determining the inclination of the head. In our study different experimenters assessed the above mentioned inclinations at our 94 subject's using a hand held inclinometer. It turned out that the results depend statistically significant on the experimenter. Data were compared to the ones assessed using the photographic method. By means of an analysis of variance in which the experimenter is considered, a significant correlation (p < 0.001) between data assessed with the two different methods was found. However, only 51% of the variance can be explained by our model. Variance might be due to inaccuracy in determining some of the points defining the Frankfurt horizontal and Reid's line, i.e. the lower orbit and the centre of the outer ear channel. The inclination of another reference line running from the tragion to the outer canthus was measured using the same subjects and the same experimental procedure as mentioned above. This line is easier to determine than the Frankfurt horizontal or Reid's line as its defining points can be assessed with greater accuracy. The inclination of this differs 10.5 degrees from the one of the Frankfurt horizontal.

Analysis of Variance↗

PubMed1995

[Personal computer used in visual function screening].

BACKGROUND: The number of medical screenings is increasing. This fact is specially pronounced in the field of occupational health. Due to restricted financial resources and limitations in time there is a need for rationalisation in medical screenings. MATERIALS AND METHODS: Possible uses of personal computers (PC) enabling organisational and financial benefits in medical screenings are suggested. By means of a test for colour-blindness it is shown how unfavourable technical conditions may be by-passed. RESULTS AND DISCUSSION: Rationalisation in medical screenings can be achieved when using the PC as a multi-functional screening-device as well as an expert system, measuring apparatus and as a communication-device. Due to a lack of literature it is difficult to discuss possible effects of technical differences between PC-based screenings of visual functions and screenings where "traditional". Reliability, sensitivity and validity is insufficiently investigated for many of the commercial available screening-devices based on a PC.

Color Perception Tests↗

PubMed1995

Treatment of choroidal neovascularization in age-related macular degeneration with interferon alpha-2a: a short term, nonrandomized pilot study.

A total of 11 patients exhibiting in 11 eyes a subfoveal or juxtafoveal choroidal neovascular membrane due to age-related macular degeneration (AMD) were treated with interferon alpha-2a (Roferon) according to a protocol that was designed for an independent, randomized, open-label pilot study to evaluate the efficacy and safety of this therapy. However, none of the patients agreed to be randomized and all elected to be treated. The average follow-up period after treatment was 8.2 months. In 6 of 7 eyes with classic choroidal neovascularization the membrane increased in size during and after treatment. Of these 6 eyes, 5 lost more than 6 lines of visual acuity. In 2 of 4 eyes with occult neovascularization the lesion enlarged. In the other 2 eyes the lesion became atrophic in 1 case and remained stable in size in the other. Visual acuity decreased by 3-9 lines in 3 eyes with occult neovascularization. Of the 11 patients, 2 discontinued interferon treatment after 8 weeks because of severe adverse reactions. From the data collected thus far in this study and in the majority of published series, we conclude that interferon alpha-2a in the dose range of 3-6 million IU given three times weekly over 8-12 weeks is neither effective nor safe for the treatment of subfoveal neovascularization in AMD.

Aged↗

PubMed1994

Direction of gaze and comfort: discovering the relation for the ergonomic optimization of visual tasks.

Perceived exertion caused by the extraocular muscles was assessed as a function of the direction of gaze and recorded in 114 subjects using a psychometric method. The results confirm statements in the literature that maximum comfort is achieved when gaze is aimed downwards. We found no correlations between perceived exertion and age or viewing distance. The relationship is relevant to ergonomics, for example in lens fitting and workplace layout.

Adult↗

PubMed1991

[Eyeglass frame for detection of eye, head movements and pupillary diameter].

Up till now, the simultaneous recording of the movements of the eyes, the movements of the head and the diameter of the pupil required the combined use of several apparatus. In this paper we present a new apparatus developed for the simultaneous recording of the movements of the eyes and of the head, and the diameter of the pupil. The apparatus consists of a portable frame (weight 215 g) a 19" rack containing electronics, and a PC for storing and analyzing the recorded data. In comparison with other systems providing similar measuring possibilities the present apparatus has the advantage of smaller dimensions and lower weight.

Computer Terminals↗

PubMed1990

Natural history of congestive gastropathy in cirrhosis. The Liver Study Group of V. Cervello Hospital.

In a prospective study of the natural history of congestive gastropathy, 212 consecutive cirrhotic patients (75 treated with sclerotherapy) were included. Mean follow-up was 46 months. Mild gastropathy (mosaiclike pattern) was found in 110 patients and severe gastropathy (granular mucosa with cherry spots) was found in 20. Prevalence of Helicobacter pylori, formerly Campylobacter pylori, was 50% in patients without, 43% in those with mild, and 28% in those with severe gastropathy. Congestive gastropathy was significantly more frequent in patients treated with sclerotherapy (83% vs. 50%, P less than 10(-5)). Sixty-month actuarial proportions of patients free of anemia (in the absence of hematemesis or melena), were 17% with severe, 62% with mild, and 93% without gastropathy (P less than 10(-8]. Corresponding figures for overt bleeding were 25%, 73%, and 87% (P less than 10(-7], whereas those for survival were 46%, 72%, and 85% (P = 0.0005), respectively. A multivariate regression analysis supported the following conclusions: (a) sclerotherapy and the presence of large esophageal varices significantly increase the risk of congestive gastropathy, which (b) is a significant risk indicator of both chronic and overt bleeding but does not independently affect survival.

Adult↗

PubMed1989

Kinetic studies of anthracycline-DNA interaction by fluorescence stopped flow confirm a complex association mechanism.

The kinetics of association and dissociation between calf thymus DNA and five anthracyclines, including doxorubicin, daunorubicin, and three synthetic analogues, were investigated with stopped flow using fluorescence detection. The sensitivity of this technique allowed us to work with submicromolar drug concentrations, thus excluding formation of aggregates, and with ratios of DNA base pairs to drug in the range 10-250, where site exclusion effects could be taken into account with a simple correction of DNA concentration and pseudo-first-order conditions were nearly fulfilled. In all cases, both association and dissociation reactions required a sum of three exponential terms to be fitted. However, satisfactory interpretation of reciprocal relaxation times as functions of DNA concentration was only achieved with kinetic models comprising a total of five steps. One of the extra steps was tentatively assigned to formation of a weakly bound, probably nonintercalated species. Another step was deduced from a comparison between results of association and dissociation experiments. The five steps are arranged, for convenience, in an association mechanism with two branches, though other mechanisms cannot be definitely ruled out. Correlation of cytotoxicity data with both association and dissociation rates is not found to be significant. This suggests that other factors must be involved in modulating the different biological properties of the investigated anthracyclines.

Animals↗

PubMed1989

Synthesis, DNA-binding properties, and antitumor activity of novel distamycin derivatives.

A group of potential alkylating agents have been synthesized that are structurally related to the oligopeptide antiviral antibiotic distamycin. All derivatives form complexes with native calf-thymus DNA but compounds 2, 3, and 6 give rise to covalent adducts. Cytostatic activity against both human and murine tumor cell lines in vitro is displayed by the new compounds. Compounds 3 and 4 are active on melphalan-resistant L1210 leukemia in mice.

Alkylating Agents↗

PubMed1989

Joint experimental and theoretical investigation of the comparative DNA binding affinities of intercalating anthracycline derivatives.

The comparative binding affinities for poly(dA-dT) and poly(dG-dC) of novel antitumor anthracyclines are reported. The data concern, besides the parent compound adriamycin (ADM), 4-demethoxy 6-deoxy 6-aminodaunomycin (II), 9-deoxy-ADM (III), 4-demethyl-6-O-methyl-ADM (IV), and 3'-deamino-3'-hydroxy-4'-epi-ADM (IV). Theoretical computations are performed in parallel for their comparative binding affinities to model double-stranded hexanucleotides, d(GCGCGC)2, d(TATATA)2, and d(CGTACG)2, using the SIBFA (sum of interactions between fragments computed ab inito) procedure. The computations reproduce in a very satisfactory manner the most salient features of the experimental comparative binding affinities. These encompass, in particular, a higher affinity for the d(TATATA)2 oligomer of II than that of ADM, despite the absence of the 14-OH substituent in II, a marked reversal of the CG versus TA sequence selectivity of the neutral compound V, favoring the d(CGCGCG)2 oligomer over the d(TATATA)2 one; and the deleterious effect incurred on the binding affinities by the presence of an O-methyl substituent at position 6 of the chromophore.

Antibiotics, Antineoplastic↗