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W Stephan

Publications and source records attributed to W Stephan.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Virus safety of labile plasma products from the German viewpoint].

Unstable plasma derivatives are sterilized in Germany according to three methods. Combined treatment with beta-propiolactone + UV irradiation: in use at Biotest since 1968; Pasteurisation in sulution, 10 h at 60 degrees C in the presence of a maltose-glycin stabilizer; in use at Behring Werke since 1980; Treatment with solvent + detergent (tri-n-butyl phosphate + Tween 80 (sodium cholate]: in use at DRK Hagen and Biotest since 1987/88. The safety of unstable plasma derivatives sterilized according to these methods has been shown in studies in chimpanzees as well as in clinical studies.

Blood Preservation↗
PubMed1988

Inactivation of the Hutchinson strain of hepatitis non-A, non-B virus in intravenous immunoglobulin by beta-propiolactone.

beta-propiolactone (beta-PL) treatment has been evaluated for its ability to inactivate 10(3.5) chimpanzee infectious doses (CID50) of the Hutchinson strain of hepatitis non-A, non-B virus (HNANBV). Two chimpanzees were inoculated with a beta-PL-treated immunoglobulin solution to which this dose of the titrated virus had been added prior to beta-PL treatment. beta-PL treatment was performed in accordance with the production procedure used for a licensed intravenous immunoglobulin preparation. Neither animal developed hepatitis. When subsequently challenged with the same spiked immunoglobulin solution that had not been beta-PL treated, both animals developed clear-cut hepatitis non-A, non-B. The results of this experiment demonstrate that beta-PL treatment is effective for the inactivation of hepatitis non-A, non-B virus in intravenous immunoglobulin.

Animals↗
PubMed1988

[Monitoring of sterilization procedures for plasma derivatives using bacteriophages].

Since 1968 the combination of beta-propiolactone (beta-PL) plus UV-inactivation for the sterilization of plasma derivatives is in use at Biotest. In 1981, a bacteriophage test system was established for routine monitoring of the efficacy of this sterilization procedure, using the bacteriophages phi x 174, phi e, Kappa and f2. In the period of 1981 to 1986, 88 control experiments were performed under production conditions demonstrating a mean inactivation of these test viruses of greater than or equal to 6.7 log10. This constant and high efficacy of the beta-PL/UV sterilization procedure guarantees the longstanding safety of beta-PL/UV sterilized blood derivatives. Bacteriophages are also useful experimental viruses for monitoring the efficacy of pasteurization processes.

Blood Preservation↗
PubMed1987

Inactivation of HIV in plasma derivatives by beta-propiolactone and UV irradiation.

The inactivation of HIV in human plasma and plasma derivatives by combined treatment with beta-propiolactone and UV-irradiation was investigated. beta-propiolactone inactivated greater than or equal to 3.5 log10 and UV greater than or equal to 2.8 log10 HIV in plasma and beta-propiolactone greater than or equal to 3.5 log10 in cryoprecipitate and UV irradiation greater than or equal to 4.5 log10 in factor VIII concentrate.

Drug Contamination↗
PubMed1987

[The effect of immunoglobulin M-enriched intravenous immunoglobulins against bacterial infections and on the neutralization of bacterial toxins].

Studies on the Efficacy of Immunoglobulin M Enriched Intravenous Immunoglobulins against Bacterial Infections and in Neutralization of Bacterial Toxins. An essential component of the new i.v. immunoglobulin product Pentaglobin is immunoglobulin M (IgM), which is concentrated in this preparation. The efficacy of this IgM containing preparation in comparison to conventional i.v. immunoglobulins was demonstrated in mouse protection tests and by in vitro neutralization of bacterial toxins. The IgM containing immunoglobulin preparation has significantly higher protection rates against gram-positive and gram-negative bacteria in mouse protection tests compared to immunoglobulin G (IgG) preparations. Bacterial toxins of Pseudomonas aeruginosa and Staphylococcus aureus are likewise more effectively neutralized by the IgM containing immunoglobulin preparation.

Animals↗
PubMed1987

Virus safety of beta-propiolactone treated plasma preparations. Clinical experiences.

Sterilization of human plasma with beta-propiolactone and UV-irradiation (cold sterilization) has been shown to be effective for a number of common pathogenic viruses. We have published data on the hepatitis safety of cold sterilized factor IX concentrates (PPSB) in healthy volunteers. This study has now been extended to include 6 virgin hemophilia B patients, who have been treated with cold sterilized PPSB for a period of up to 5 years. None of these volunteers or patients exhibited clinical symptoms or laboratory data indicating the transmission of either viral hepatitis (B or NANB) or acquired immunodeficiency syndrome (AIDS). Hyperimmunoglobulin (HIg) preparations from cold sterilized plasma, offering protection against hepatitis B and NANB are also safe regarding HTLV-III virus transmission, even though these preparations may contain HTLV-III antibody titers up to 1:1000.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The evolution of restricted recombination and the accumulation of repeated DNA sequences.

We suggest hypotheses to account for two major features of chromosomal organization in higher eukaryotes. The first of these is the general restriction of crossing over in the neighborhood of centromeres and telomeres. We propose that this is a consequence of selection for reduced rates of unequal exchange between repeated DNA sequences for which the copy number is subject to stabilizing selection: microtubule binding sites, in the case of centromeres, and the short repeated sequences needed for terminal replication of a linear DNA molecule, in the case of telomeres. An association between proximal crossing over and nondisjunction would also favor the restriction of crossing over near the centromere. The second feature is the association between highly repeated DNA sequences of no obvious functional significance and regions of restricted crossing over. We show that highly repeated sequences are likely to persist longest (over evolutionary time) when crossing over is infrequent. This is because unequal exchange among repeated sequences generates single copy sequences, and a population that becomes fixed for a single copy sequence by drift remains in this state indefinitely (in the absence of gene amplification processes). Increased rates of exchange thus speed up the process of stochastic loss of repeated sequences.

Animals↗
PubMed1985

Inactivation of the Hutchinson strain of non-A, non-B hepatitis virus by combined use of beta-propiolactone and ultraviolet irradiation.

A beta-propiolactone/ultraviolet irradiation procedure (beta PL/UV) has been evaluated for its ability to inactivate 30,000 chimpanzee infectious doses of the Hutchinson strain of non-A, non-B (NANB) virus. The chimpanzees were inoculated with plasma to which this dose of the titrated virus had been added prior to application of the beta PL/UV process in accordance with a procedure used for licensed blood derivatives in Germany. Neither animal developed hepatitis. When subsequently challenged with the same contaminated plasma, which had not been sterilized, both animals promptly developed typical NANB hepatitis. This study extends the high (approximately 10(7)-fold) process efficiency of the beta PL/UV procedure previously reported for hepatitis B virus to a blood-borne NANB virus.

Animals↗