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Biomedical subjects

I Johansen

Publications and source records attributed to I Johansen.

At least 19 recordsLinked to original sources
PubMed2005

High prevalence of drug-resistant tuberculosis, Republic of Lithuania, 2002.

BACKGROUND: Nations of the former Soviet Union have the world's highest reported levels of resistance to anti-tuberculosis drugs. We conducted the first national survey of anti-tuberculosis drug resistance in the Republic of Lithuania. METHODS: We tested Mycobacterium tuberculosis isolates from all incident culture-positive pulmonary TB patients registered in 2002. New patients were those treated for <1 month with any first-line anti-tuberculosis drug (isoniazid [INH], rifampin [RMP], ethambutol, or streptomycin); previously treated patients were those treated for > or =1 month. RESULTS: Of 1163 isolates, 475 (41%) were resistant to at least one first-line drug, and 263 (23%) were resistant to at least INH and RMP (MDR); this included 76/818 (9.3%) from new patients and 187/345 (54%) from previously treated patients. Of 52 MDR isolates randomly selected for extended testing at an international reference laboratory, 27 (51%, 95%CI 38-66) had resistance to pyrazinamide, 21 (40%, 95%CI 27-55) to kanamycin, and 9 (17%, 95%CI 8-30) to ofloxacin. CONCLUSIONS: The prevalence of MDR-TB in Lithuania is among the world's highest. Among MDR-TB isolates, aminoglycoside and fluoroquinolone resistance were common. To combat drug-resistant TB, Lithuania has implemented the WHO global TB control strategy (DOTS), and is developing an MDR-TB treatment program (DOTS-Plus).

Adolescent↗
PubMed2001

Cancer incidence among Danish workers exposed to trichloroethylene.

Human evidence regarding the carcinogenicity of the animal carcinogen trichloroethylene (TCE) is limited. We evaluated cancer occurrence among 803 Danish workers exposed to TCE, using historical files of individual air and urinary measurements of TCE-exposure. The standardized incidence ratio (SIR) for cancer overall was close to unity for both men and women who were exposed to TCE. Men had significantly elevated SIRs for non-Hodgkin's lymphoma (SIR = 3.5; n = 8) and cancer of the esophagus (SIR = 4.2; n = 6). Among women, the SIR for cervical cancer was significantly increased (SIR = 3.8; n = 4). No clear dose-response relationship appeared for any of these cancers. We found no increased risk for kidney cancer. In summary, we found no overall increase in cancer risk among TCE-exposed workers in Denmark. For those cancer sites where excesses were noted, the small numbers of observed cases and the lack of dose-related effects hinder etiological conclusions.

Denmark↗
PubMed2000

[Experiences with teleradiology in general practice in Oppland].

BACKGROUND: Our aim was to evaluate one year of operation of a newly established teleradiology service for people in Mid- and North Gudbrandsdalen (30,000 inhabitants). In Otta, one radiographer works with digital pictures (phosphorus plate technology). Pictures are sent to the local hospital in Lillehammer (115 kilometres away) by a broadband network (for health services only) for radiological evaluation. MATERIAL AND METHODS: We have measured the scope of the service, patient satisfaction, management stability and efficiency, and financial aspects (the latter are not included in this article). RESULTS: Over one year we have examined 3,081 persons (skeleton, thorax, sinuses). A majority of patients (90%) thought it was better for them to be examined at Otta. Waiting time was short, rarely more than one week. No re-examinations due to insufficient picture quality were required. Some expected and some unexpected problems occurred. Pictures from 37 patients were lost and could not be radiologically evaluated. The lead time from when pictures were taken to when the requisitioning doctor received the report, was too long (one to three weeks). The digital pictures are not easily available to hospital physicians. Copies must be made on film. INTERPRETATION: Our experience is positive. Most problems will be solved by storing copies at Otta, by better organisation of the radiologic service, and by establishing a digital picture archiving and communication system (PACS) at the hospital.

Cost Savings↗
PubMed1999

Barriers for dissemination of a national health care data network. A list of recommendations for better dissemination.

Establishment of a Danish Nation-wide Health Care Data Network for exchange of health care related information using standardised EDIFACT messages is agreed between the Danish Government, the Hospital Owners and the GPs organisations. The aim is, within year 2000 in the MedCom project, to reach a level of 66% of all messages between the secondary and primary health sector must be send electronically using EDIFACT. There are many barriers for reaching this goal, and to reveal this barriers an investigation was done, and a list of recommendations are set up. The investigation was based upon literature, interviews and most important a questionnaire among 200 GPs and specialists all over the country. After 6 months where the recommendations have been handled there is seen an increase in communicated messages on 40%, and from January 1999 more than 1.1 mill messages are exchanged each month.

Communication Barriers↗
PubMed1999

Third generation electronic pharmacy communications. Recommendations based on ten years' experience.

The number of electronic prescriptions in Denmark is increasing and almost 600,000 electronic prescriptions are now sent every month. There is therefore a strong interest in directly reusing the data entered in the medical practitioner systems in the pharmacy systems. It has therefore been decided to introduce a shared data foundation in all medical practitioner and pharmacy systems in Denmark in conjunction with the introduction of the new MEDPRE electronic prescription standard. Parallel to the standardisation work, concrete guidelines have been prepared for the individual EDP (Electronic Data Processing) systems to ensure rapid, problem-free prescription communication. The aim in the longer term is for 95% of all EDIFACT prescriptions to reach the receiving pharmacy no more than 20 minutes after being sent from a medical practice.

Computer Communication Networks↗
PubMed1994

Ultrasonic tomography of biological tissue.

In this paper, quantitative tomographic reconstructions of biological tissue are presented. First, the experimental setup and a hybrid filtered backpropagation (FBP) technique are briefly described. Using this technique, which includes exact backpropagation of data prior to reconstruction by means of the classical FBP algorithm, quantitative velocity maps of relatively large biological objects can be obtained. Since the FBP algorithm is based on a first-order scattering approximation, the deteriorating effects of higher-order scattering in diffraction tomography are also discussed. The higher-order scattering limits the size of the biological object to a few centimeters.

Algorithms↗
PubMed1991

Experimental results in ultrasonic tomography using a filtered backpropagation algorithm.

This paper describes an experimental study in diffraction tomography whose main goal was to determine experimentally the performance of the filtered backpropagation algorithm in ultrasound tomography. We have built a simple water tank with a plane wave source and a scanning hydrophone. The test objects have been cylindrical and of a relatively simple structure and made of acrylic and silicone rubber. The resulting reconstructions show that the structure and position of the objects are well reproduced. The velocity of the objects can also be well reproduced if the velocity contrast is not too large. In medical imaging, it is most important to see the structure, and since the velocity change in biological tissue is small, the method should be well suited for medical imaging.

Algorithms↗
PubMed1975

The radiobiology of DNA strand breakage.

The yield of single-strand breaks in lambda DNA within lysogenic host bacteria was measured after exposure to 4-MeV electrons (50 msec) and rapid transfer (45 msec) to alkaline detergent. In nitrogen anoxia the yield was 1.2 X 10(-12) DNA single-strand breaks per rad per dalton, and under full oxygenation the yield increased to 5 X 10(-12) breaks per rad per dalton. A search for the presence of fast repair of strand breaks operating within a fraction of a second. Strand breaks produced in the persence of oxygen were repaired in 30-40 sec, while breaks produced under anoxia were rejoined even slower. A functional product from the po[A] gene was needed for the rejoining of the broken molecules. Intermediate levels of DNA strand breakage seen at low concentrations of oxygen are dependent on the concentration of cellular sulfhydryl compounds, suggesting that in strand breakage oxygen donors compete for reactions with radiation-induced transients in the DNA. Intercomparisons of data on radiation-induced lethality of cells and single-strand breaks in episomal DNA allow the distinction between two classes of radiation-induced radicals, R-1 and R-2, with different chemical properties; R-1 reacts readily with oxygen and N-oxyls under formation of potentially lethal products. The reactivity of oxygen in this reaction is 30-40 times higher than that of TMPN. R-2 reacts 16 times more readily that R-1 with oxygen under formation of single-strand breaks in the DNA. R-2 does not react with N-oxyls.

Aerobiosis↗
PubMed1975

DNA strand breaks measured within 100 milliseconds of irradiation of Escherichia coli by 4 MeV electrons.

A method was developed in which E. coli cells were irradiated with four MeV electrons and transferred to alkaline detergent within a fraction of a second. This technique minimizes the amount of repair of radiation damage before analysis without the necessity of using physical or chemical treatments to inhibit repair and alter the physiological condition of the cells. The yield of DNA strans breaks formed in covalent circular superhelical lambda DNA molecules superinfecting E. coli lysogens was about 4-fold greater when the cells were irradiated in oxygen than when they were irradiated under nitrogen anoxia. The same yields were obtained in phosphate buffer at 3 degrees and 22 degrees as well as in growth medium at 37 degrees, and the yields were not altered by the polA1 mutation. When E. coli lysogenic cells superinfected with lambda were irradiated with doses sufficient to introduce at least seven breaks in the phage DNA, the chromosomal DNA and the superinfecting phage DNA sedimented similarly in alkaline sucrose gradients, indicating that both DNAs were broken to a similar extent during irradiation. However, the yield of breaks calculated for chromosomal DNA in similar experiments was greater than the yield calculated from the first break introduced into covalent circular lambda DNA molecules. These apparently contradictory results are explicable either if the initial break in a superhelical molecule occurs with an efficiency different from that for subsequent breaks, or if the pulsed electron radiation produces a high proportion of double-strand breaks.

Centrifugation, Density Gradient↗