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Biomedical subjects

B Oberg

Publications and source records attributed to B Oberg.

At least 91 records · Page 5Linked to original sources
PubMed1988

Reverse transcriptases from human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIVMAC) are susceptible to inhibition by foscarnet and 3'-azido-3'-deoxythymidine triphosphate.

Reverse transcriptases from human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV) were investigated with respect to susceptibilities to the reverse transcriptase inhibitors foscarnet and 3'-azido-3'-deoxythymidine triphosphate (AZTTP). The different reverse transcriptases had the same sensitivity to foscarnet (50% inhibition at 0.10 to 0.16 microM). The Ki values for AZTTP were 0.01 to 0.02 microM for HIV-1 reverse transcriptase and 0.02 to 0.03 microM for HIV-2 and SIVMAC reverse transcriptases.

Animals↗
PubMed1988

Antiviral therapy.

The complicated machinery used by HIV for multiplication offers several targets for therapy and the viral enzymes appear to be particularly appropriate targets. For the HIV reverse transcriptase, this has been demonstrated by the clinical effect of zidovudine, but less toxic drugs are needed. The HIV protease is another viral enzyme against which inhibitors are likely to be developed. As the function and structure of HIV proteins are understood in more detail, it will become possible to construct more selective inhibitors. It is necessary to evaluate new HIV inhibitors in animal models to facilitate the rapid selection of suitable compounds and combinations for further clinical evaluation. It appears likely that several drugs preventing HIV replication will be required, and that these will appear during the next few years, but it is also apparent that the elimination of HIV from a patient remains a remote possibility.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Characterization of EBV-carrying B-cell populations in healthy seropositive individuals with regard to density, release of transforming virus and spontaneous outgrowth.

Peripheral or tonsil lymphocyte populations of EBV-seropositive donors give rise to EBV-carrying LCLs upon in vitro explantation. Such lines can arise either by a 2-step mechanism, namely release of virus from some of the explanted cells followed by infection of previously uninfected B cells, or by direct outgrowth of virus-harboring B cells (Rickinson et al., 1974; Dalens et al., 1975; Hinuma and Katsuki 1978; Katsuki et al., 1979). We observed that cells responsible for both the 2-step mechanism and for direct outgrowth are found in the purified B-cell compartment. Virus release was more frequent than direct outgrowth. The majority of virus-releasing cells were found in the low-density fraction that contains large, activated B blasts. Cells that were capable of spontaneous outgrowth in the presence of the viral inhibitor PFA and of virus-neutralizing antibody gave rise to cell lines that carried the sex chromosome marker of the original donor, rather than that of admixed cord blood lymphocyte of the opposite sex. Such cells were found in both the low- and the high-density fractions. The majority of the EBV-carrying B cells in vivo are thus low-density blasts. Rare small B cells of high density harboring EBV were capable of spontaneous outgrowth. This may be indicative of a host control mechanism that is removed upon cultivation in vitro.

B-Lymphocytes↗
PubMed1987

Inhibition of hepatitis B virus DNA polymerase by 3'-azido-3'-deoxythymidine triphosphate but not by its threo analog.

An inhibitory effect of 3'-azido-3'-deoxythymidine triphosphate on hepatitis B virus DNA polymerase was found. No effect was seen by its threo analog. The effect was detected at and above a concentration of 0.05 microM. The inhibition of DNA polymerase activity was the same in ten different strains of HBV. The mechanism was shown to be competitive, with an inhibition constant (Ki) of approximately 0.04 microM, and the Km value for dTTP was 0.1 microM.

Antiviral Agents↗
PubMed1987

Inhibition of the reverse transcriptase from HIV by 3'-azido-3'-deoxythymidine triphosphate and its threo analogue.

3'-Azido-3'-deoxythymidine triphosphate (erythro) and its threo isomer were synthesized and investigated for their inhibition of HIV reverse transcriptase from virus isolate U 937/HTLV-III. The erythro isomer was a competitive inhibitor of the reaction directed by (rA)n(dT)12-18 and the Ki value was 0.0022 microM. The threo isomer was at least 100-fold less active. The inhibition was specific for dTMP incorporation, and dGMP incorporation using (rC)n(dG)12-18 as template/primer was not affected. The Km value for dTTP varied between 0.7 microM and 1.7 microM. Reverse transcriptase from nine HIV isolates were tested for inhibition by the erythro isomer and only slight differences in sensitivity were observed.

Antiviral Agents↗
PubMed1987

Possible role of vacuum systems and compressed air generators in cross-infection in the ICU. A radioactive tracer study.

Cross-contamination between a hospital's vacuum and compressed air systems was demonstrated using xenon-133 as a tracer. A xenon-133 bolus was introduced to the vacuum system in the intensive care unit. Calculations based on the amount of radioactive tracer recovered from the compressed air outlet at the same location as that at which the tracer was introduced indicated that 17% of the tracer had entered the compressed air system. The contamination was caused because the vacuum and compressed air systems were located in the same machine room. This could conceivably provide a route for respiratory tract contamination in patients receiving ventilatory assistance with air-oxygen mixtures.

Air↗
PubMed1987

Different patterns of inhibition of avian myeloblastosis virus reverse transcriptase activity by 3'-azido-3'-deoxythymidine 5'-triphosphate and its threo isomer.

The two isomers 3'-azido-3'-deoxythymidine 5'-triphosphate (erythro-AZT-TP) and 1-(3'-azido-2',3'-dideoxy-beta-D-xylofuranosyl)thymine 5'-triphosphate (threo-AZT-TP) were studied as inhibitors of the reverse transcriptase activity of avian myelobastosis virus. Kinetic analysis of the (rA)n X (dT)12-18 (a standard template primer complex of polyriboadenylate and oligodeoxythymidylate of indicated length)-directed reaction revealed that erythro-AZT-TP was a competitive inhibitor with respect to dTTP, whereas threo-AZT-TP was a noncompetitive inhibitor. The apparent Ki values, as calculated from Dixon plots, were 0.48 and 5.5 microM, respectively, compared with a Km value for dTTP of about 70 microM. These results indicate that erythro-AZT-TP had an approximately 150-times-higher affinity to the enzyme than dTTP had and that the avian myeloblastosis virus reverse transcriptase had different binding sites for the two isomers.

Avian Leukosis Virus↗
PubMed1987

Testing of isokinetic muscle strength in the ankle.

The purpose of this study was to evaluate isokinetic strength measurement in ankle joint. The study was divided into three parts. A comparison of dorsal and plantar flexion with and without consideration to the biomechanical circumstances was done. The series comprised 15 men and 10 women. A comparison of strength measurements of dorsal flexion with and without fixation of the upper trunk. The series consisted of 10 men. A reference series for dorsal and plantar flexion comprising 15 men (mean age = 34 +/- 9 yr) was used for comparison. Strength was tested at 0 degree, 15 degrees, 30 degrees, 60 degrees, 120 degrees, 180, and 240 degrees/s. The readings made without biomechanical adjustment were significantly higher than connected readings. Mean difference at 30 degrees/s was 8.4 +/- 7.1 Nm for dorsal flexion and 18 +/- 3.1 Nm for plantar flexion. The torque values were significantly higher when the upper trunk was not immobilized, and higher standard deviations were obtained. The left (viz. dominant) leg produced significantly higher muscle torque at all velocities for plantar flexors and at all but 180 degrees and 240 degrees/s for dorsal flexors. The regression coefficient was used as a measure of peak torque velocity relation, the coefficient was -0.50 +/- 0.16 for plantar flexion and -0.22 +/- 0.06 for dorsal flexion.

Adult↗
PubMed1986

Influence of twenty potentially antiviral substances on in vitro multiplication of hepatitis A virus.

A multiwell tissue culture system was developed to study the influence of various substances on hepatitis A virus (HAV) propagation. A panel of 20 substances of different structure types, each with known effect against at least some viruses, was studied at a concentration of 100 microM. Three substances showed reproducible inhibition. The strongest inhibitor, arabinosylcytosine, also produced cytotoxic changes in cells down to a concentration of 1 microM, and its effect was considered as nonspecific. Amantadine and ribavirin showed a moderate effect at 100 microM. A stronger inhibition was seen at 250 and 500 microM, doses that are toxic and impractical for clinical use. Although no promising candidates for antiviral treatment of hepatitis A have emerged from the present study, the assay model described here would seem useful in the screening of substances with inhibitory effects on HAV.

Amantadine↗
PubMed1986

Isokinetic torque levels for knee extensors and knee flexors in soccer players.

The knee extensor and knee flexor strengths were measured isokinetically (30 degrees, 180 degrees/s) and isometrically with a Cybex II device in three groups of male soccer players (national team players, n = 13; division I, n = 15; division IV, n = 180) and a group of nonsoccer players (n = 32). There were difference in strength between soccer players and nonsoccer players and between players from different divisions. Correction for body surface area did not affect the results. The knee flexor/knee extensor ratio (H/Q ratio) was significantly higher for soccer players than for nonsoccer players. The fast-speed/slow-speed ratio for knee extensors was higher for nonsoccer players and for national team players than for players from divisions I and IV.

Biomechanical Phenomena↗
PubMed1986

Bacterial contamination of compressed air for medical use.

The present study demonstrates a previously unnoticed source of bacterial contamination of locally manufactured compressed air for medical use. Air samples were drawn into a specially constructed device, and bacterial contents were identified from growth on agar plates. Various factors contributing to bacterial contamination of compressed air during production are mentioned and preventive measures are discussed.

Air Microbiology↗