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Biomedical subjects

D Adam

Publications and source records attributed to D Adam.

At least 19 recordsLinked to original sources
PubMed1992

Cross-linking of surface immunoglobulin activates src-related tyrosine kinases in WEHI 231 cells.

Crosslinking of sIgM on the B cell line WEHI 231 with anti-sIgM antibody induces protein tyrosine phosphorylation, implicating protein tyrosine kinases (PTKs) in sIg-mediated signal transduction. We have analyzed this cell line for members of the src family of PTKs and have evaluated whether these PTKs might be involved in the process of sIgM-mediated signaling. Our results show that Blk, Lyn, Lck, and Hck are detectable in WEHI 231 cells. Addition of antibodies to sIgM were found to variably stimulate the activities of Blk, Lyn, Lck, and Hck as measured by immune-complex protein kinase assays. Autophosphorylation of these src PTKs, as assessed by reaction with anti-phosphotyrosine antibodies, increased over the time course of sIgM-mediated activation. Co-immunoprecipitation studies to investigate the potential physical interaction of src PTKs with the sIgM receptor complex revealed that, under digitonin and Brij 96 lysis conditions Lyn, Lck, Hck, but not Blk associated with sIgM.

Animals↗
PubMed1992

Conservation and characterisation of spatial features in a new method of data compression for body surface potential maps.

Body surface potential maps consist of a huge amount of data represented as a series of three-dimensional maps, which are time consuming to process and expensive to store. In spite of the continuous interest in body surface potential maps, their use has not become common and they are of no practical use in the clinics. This is due to the overwhelming amount of measured data required to generate the maps and the lack of quantitative methods to analyse them. Data compression or reduction may solve these deficiencies. Such a procedure must conserve the fine spatial details of the maps, which are usually extracted from low level surface potentials, as these are reported to be significant in diagnostic electrocardiography. A technique is presented for data reduction, that implements two-level thresholding and conserves the fine significant spatial features of each map. A sequence of annuli thus produced is shown to describe the dynamic nature of the underlying process. This sequence is further processed and characterised by features which quantify its dynamic behaviour: time of annuli sequence appearance, its duration, three-dimensional loci of centres of mass of the annuli, distances between successive centres of mass and cross-correlation coefficients between successive annuli. To test the data reduction procedure and the usefulness of the features, maps from 20 subjects are studied (both normal patients and those with various pathologies). It is found that the use of annuli instead of the whole measured information allows simple storage, display and calculations; the features, which vary in time, represent closely the changes in location of the annuli and their dynamic variations of shape. The features are also found to be grouped together for the maps of the normal patients and for each pathology. Thus, body surface potential maps may become more commonly used in clinics by being represented by a set of features, which conserve their dynamic and spatial nature, and which may serve for classification of cardiac pathologies.

Action Potentials↗
PubMed1992

Classification of pathologies by reduced sequential potential maps.

Body surface potential mapping (BSPM) is an electrocardiographic measuring technique which produces the data as a series of three-dimensional maps. These maps are assumed to contain information which may help classify subjects for diagnostic purposes more effectively than standard ECGs. As quantitative classification of the complete sequences of maps is complex and cumbersome, the present study uses extracted features which characterise the data. The features, which have been presented and evaluated in a recent work, have been extracted after the maps were processed by a compression technique which conserved the spatial details of the maps. The compression by two-level thresholding converted the sequences of maps into sequences of annuli, from which the following features were extracted: time indices, velocity vector magnitude, loci in three-dimensional space of the centres of mass and cross-correlation coefficients between successive annuli in the sequence. Here, three different classification methods are applied to these features: statistical methods, the Fisher linear discriminant method and visual inspection. BSPMs from 54 subjects are used: 25 normal, 11 WPW syndrome and 18 CAD cases. It is found that by applying a decision role which comprises all features, the procedure offers a completely accurate classification of the subjects to their groups. The three-dimensional centre of mass is found to be the single best classifier; successfully categorising 20/25 of the normals 17/18 of the CAD patients and 11/11 of the WPW patients.

Action Potentials↗
PubMed1992

Portable system for acquisition and transmission of ECG parameters.

A simple inexpensive bedside automatic ECG data-collection system is presented. The main parameter measured is the R-R interval length that can be used in the construction of a heart rate variability signal. Another parameter measured is the shape of the T-wave in the ECG signal. The collected data are transferred to a remote host computer through the public telephone network, by means of a modem. The system can function through the whole range of human heart rates. The described solution differs from most existing ones by utilising the existing ECG monitoring equipment in hospitals, which usually does not store any information. This equipment is connected by a portable, independent, special-purpose system to a remote host computer which can further analyse and store the data.

Computer Communication Networks↗
PubMed1992

Clinical use of the new macrolides, azalides, and streptogramins in pediatrics.

Macrolides are the primary drugs of choice for a number of clinically significant infections in children. The clinical aspects of newer macrolides such as roxithromycin, clarithromycin, dirithromycin, flurithromycin, miocamycin, rokitamycin, azithromycin and RP 59500 are discussed in different pediatric infections including streptococcal infections (e.g. pharyngitis, otitis, pneumonia, skin infections), staphylococcus soft tissue infections, mycoplasma pneumonia, chlamydial infections as well as legionellosis and campylobacter enteritis. Also, incidences of adverse events in pediatric patients receiving different macrolides are indicated as well as the dosages in children. The advantages of newer macrolides are: lower dosages, b.i.d. or once daily dosage regimens, good intracellular and tissue penetration, better activity against gram-negative microorganisms (some) and a low rate of adverse reactions.

Adolescent↗
PubMed1992

[An economic comparison between digital luminescence radiography and conventional film processing in intensive care medicine].

The costs of a conventional film-screen radiography daylight-system and storage-phosphor computed radiography (Fuji AC-1) are compared. In 1990, 3841 radiologic procedures (mostly portable chest X-rays) were performed in 3474 patients of a surgical intensive care unit. With conventional film-screen radiography 6.8% retakes were necessary for diagnostic or technical reasons. Comparing the fixed and variable costs of both systems conventional film-screen radiography was more economic under the given conditions of the test. It is concluded that computed radiography in intensive care patients has definite advantages in terms of image quality and reproducibility, however, in order to compete successfully in the economic turf CR has to be implemented in a picture archiving and communication system (PACS).

Costs and Cost Analysis↗
PubMed1992

[A career in nursing sciences?].

A research study was conducted in a francophone high school in Northern Ontario to examine students' perceptions of nursing and the influence of these perceptions on nursing as a career choice. All students in grades 11, 12 and 13 were invited to participate. Fifty-eight percent (n = 268) completed the questionnaire. Results showed that 37 percent of the respondents considered pursuing a career in the health sciences. Only 14% percent were interested in nursing. Respondents' comments suggest that the nurse is viewed favorably but the profession is perceived as a career that does not involve pleasant tasks, good working conditions or opportunities for professional advancement. Reasons advocated for choosing nursing were altruistic rather than career-oriented. Students saw nursing practice as occurring mainly in a hospital setting. Half of the respondents who had chosen nursing as a career opted to enroll in a university program and the other half chose a college program. Results suggest that nursing continues to face an image problem regarding its role in the health care system. In these times of job losses and budget cuts, the profession still needs to attract young recruits. This is the challenge we have to face.

Adolescent↗
PubMed1991

Comparison between single signed integral pulse frequency and sine wave crossing modulation techniques.

The single signed integral pulse frequency modulation (SS-IPFM) is used in modeling neural communication processes. The reference signal crossing and in particular sine wave crossings (SWC) are used to describe physiological processes like vision. Under some restrictions upon the input signal it is possible to define SS-IPFM and SWC systems with identical output for the same modulation input. These restrictions and the exact compositions of the encoders are examined by comparison of both SS-IPFM and SWC to general form of Pulse Position Modulation (PPM) technique.

Cybernetics↗
PubMed1991

Penicillin concentration in the compact bone of the mandible.

During surgical removal of impacted third molars, the concentration of Penicillin G was determined in the compact bone of the mandible. Fifteen patients received 5 million IU and 15 received 10 million IU of Penicillin G intravenously as a single dose before surgery began. In both groups concentrations of penicillin with a bactericidal effect on most pathogenically relevant oral bacteria were detected during osteotomy. Taking into account the considerable interindividual variation, the one-shot application of 10 million IU of Penicillin G was more effective in certain cases than the 5 million IU dose. The factors influencing the decision on the high single-dose application include expected length of operation, body weight, kidney function, and infusion period. Assuming that in intraoral osteotomies the bone becomes contaminated with bacteria that are highly sensitive to penicillins, the results indicate that preoperative infusion of Penicillin G could be an effective method of preventing wound infection.

Adolescent↗
PubMed1991

Transcriptional activation of the melanoma inducing Xmrk oncogene in Xiphophorus.

The melanoma inducing locus of Xiphophorus encodes a tumorigenic version of a novel putative receptor tyrosine kinase (Xmrk). To elucidate the mechanism of oncogenic activation of Xmrk, we compared the structure and expression of two oncogenic loci with the corresponding proto-oncogene. Only minor structural alterations were found to be specific for the oncogenic Xmrk genes. Marked overexpression of the oncogene transcripts in melanoma, which are approximately 1 kb shorter than the proto-oncogene transcript, correlates with the malignancy of the tumors. The tumor transcripts are derived from an alternative transcription start site that is used only in the oncogenic loci. Thus, oncogenic activation of the melanoma inducing Xmrk gene appears primarily to be due to novel transcriptional control and overexpression.

Animals↗
PubMed1991

Tissue concentrations of ofloxacin in necrotic foot lesions of diabetic and non-diabetic patients with peripheral arterial occlusive disease.

Six diabetic patients with infected foot lesions (mean age 64 years) and six male patients (mean age 71 years) with ischemic acral ulceration due to advanced peripheral arterial occlusive disease were treated with 200 mg ofloxacin b.i.d. The necrotic margin tissue concentrations of ofloxacin determined by HPLC and confirmed by microbiological assay were in the same range (1.6 to 6.4 mg/kg) as plasma levels (1.6 to 5.9 mg/l). No difference of plasma and tissue concentrations was found between patients with peripheral vascular disease and diabetics, respectively. After three weeks treatment bacterial wound pathogens disappeared in 7 subjects, changed in 4 patients and were resistant in one patient. Clinical improvement appeared in 9 of 12 patients after three weeks of therapy. Satisfactory tissue levels of orally administered ofloxacin were achieved in the infected necrotic tissue area of diabetic and non-diabetic patients with impaired peripheral arterial circulation.

Aged↗
PubMed1990

Complete foetal ECG morphology recording by synchronised adaptive filtration.

Present noninvasively measured indices of foetal stress are indirect and not sufficient. Foetal electrocardiography (FECG) is a potential noninvasive measurement of the foetus wellbeing which has been little utilised because of the difficulties of measuring it. The development of time-sequenced adaptive filters which are synchronised to the QRS complex by the use of Doppler echocardiography allowed the recording of relatively noise-free FECG. The paper describes the use of this technique for obtaining the complete complex of the FECG. Several sets of time-sequenced adaptive filters are combined to allow a multilead abdominal recording to produce a measurement system which rejects maternal ECG and enhances the FECG. Five subjects have been analysed, and their FECGs have been accurately reproduced with minimal changes of the filters' parameters.

Electrocardiography↗
PubMed1990

Ceftazidime concentrations in renal cysts.

Levels of ceftazidime (CAZ) in uninfected renal cysts of 25 patients were investigated. Seventeen patients received 2 g CAZ about 140 min prior to puncture of the cysts (group I), and eight patients were treated with 2 x 2 g CAZ one day before, and with a further dose of 2 g 2 h prior to puncture (group II). In eight cases (two of group I and six of group II) the concentration of the cyst fluid was also assessed at 4 h and 6 h after completion of the CAZ infusion. In group I, CAZ concentrations were 0.5 to 1.13, micrograms ml-1, mean 0.71; in group II CAZ concentrations were 3.6 to 6.7 micrograms ml-1, mean 5.55. At 4 h and 6 h after infusion the mean cyst concentrations were 4.4 and 2.9 micrograms ml-1, respectively.

Adult↗