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A Janssen

Publications and source records attributed to A Janssen.

48 records · Page 3Linked to original sources
PubMed1988

The dihydrolipoyltransacetylase component of the pyruvate dehydrogenase complex from Azotobacter vinelandii. Molecular cloning and sequence analysis.

The gene encoding the dihydrolipoyltransacetylase component (E2) of the pyruvate dehydrogenase complex from Azotobacter vinelandii has been cloned in Escherichia coli. A plasmid containing a 2.8-kbp insert of A. vinelandii chromosomal DNA was obtained and its nucleotide sequence determined. The gene comprises 1911 base pairs, 637 codons excluding the initiation codon GUG and stop codon UGA. It is preceded by the gene encoding the pyruvate dehydrogenase component (E1) of pyruvate dehydrogenase complex and by an intercistronic region of 11 base pairs containing a good ribosome binding site. The gene is followed downstream by a strong terminating sequence. The relative molecular mass (64913), amino acid composition and N-terminal sequence are in good agreement with information obtained from studies on the purified enzyme. Approximately the first half of the gene codes for the lipoyl domain. Three very homologous sequences are present, which are translated in three almost identical units, alternated with non-homologous regions which are very rich in alanyl and prolyl residues. The N-terminus of the catalytic domain is sited at residue 381. Between the lipoyl domain and the catalytic domain, a region of about 50 residues is found containing many charged amino acid residues. This region is characterized as a hinge region and is involved in the binding of the pyruvate dehydrogenase and lipoamide dehydrogenase components. The homology with the dihydrolipoyltransacetylase from E. coli is high: 50% amino acid residues are identical.

Acetyltransferases↗
PubMed1988

Relationship between internalization and cytotoxicity of ricin A-chain immunotoxins.

Immunotoxins (ITs) appear to vary considerably in their killing efficiency towards antigen positive cells. In order to unravel the mechanisms underlying these differences, the parameters responsible for these variations were studied. The efficacy of the monoclonal antibodies (MoAbs) WT32 (CD3), OKT4 (CD4), T101 (CD5), WT1 (CD7) and WT82 (CD8) conjugated to ricin A-chain was expressed by the extent of protein synthesis inhibition of four leukaemic T cell lines (CEM, GH1, Jurkat and HPB-ALL). Large differences in cytotoxicity were observed. Efficient inhibition of protein synthesis was seen with anti-CD3 IT, anti-CD5 IT and anti-CD7 IT. In these cases the cytotoxicity was related to the antigen density on the target cell membrane. Anti-CD4 IT inhibited poorly and anti-CD8 IT was ineffective, even on cell lines with a high expression of the corresponding antigen. When antigen density and cytotoxicity were plotted for all CD antigens, no correlation could be found. Subsequently, internalization was studied with 125Iodine-labelled antibodies. Anti-CD7 showed the fastest internalization rate, followed by anti-CD3 and anti-CD5. Anti-CD4 and anti-CD8 antibodies were respectively moderately and hardly internalized. When the absolute amount of internalized MoAb was calculated, a highly significant correlation with cytotoxicity was found. We conclude that the degree of antigen expression is not so important as the absolute amount of antibody internalized in predicting the efficacy of ITs.

Antibodies, Monoclonal↗
PubMed1982

Characterization of immunogenic properties of haptenated liposomal model membranes in mice. VII. Synergistic responses to haptenated liposomes and haptenated thymus-dependent antigens in CBA/N mice.

CBA/N mice have an X-linked B-cell defect which prevents them from responding to non-mitogenic thymus-independent (TI-2) antigens such as haptenated Ficoll. The CBA/N mice do, however, respond to another group of thymus-independent (TI-1) antigens among which are haptenated liposomes. The F1 male progeny of CBA/N female mice express the same characteristics. Hapten-specific plaque-forming cell (PFC) responses to haptenated proteins (thymus-dependent, TD, antigens) by CBA/N mice and CBA/N x C3H/HeN F1 male mice can be blocked by concomitant exposure to TI-2 antigens bearing the same hapten. Simultaneous exposure to haptenated liposomes (TI-1 antigen) and TD antigens, however, results in a synergistic response to the hapten if the antigens share common epitopes. The tripeptide-enlarged hapten dinitrophenyl-beta-alanylglycylglycine (J), conjugated to phosphatidyl-ethanolamine (PE) and incorporated into liposomal model membranes, was used throughout the experiments. In F1 male mice the moderate responses to TD antigens could be restored to values equivalent to those seen in F1 female mice. This adjuvant effect of haptenated liposomes is hapten-specific, time-dependent, and restricted to certain structural forms of the liposomes.

Animals↗
PubMedDate not supplied

A double-blind, placebo-controlled evaluation of the efficacy and safety of loreclezole as add-on therapy in patients with uncontrolled partial seizures.

Sixty-two patients with uncontrolled partial seizures participated in a 12-week, double-blind, placebo-controlled add-on-trial. Thirty-two patients received loreclezole and 30 a placebo as add-on therapy. Loreclezole was targeted at a plasma level of 1-2 mg/l. In spite of an antiepileptic therapy, usually with 2 or 3 antiepileptic drugs, these patients had at least 4 seizures a month during the baseline period. At the end of the treatment phase with loreclezole and placebo, individual responses varied widely. The median change in the daily seizure frequency was not significantly different in the 2 groups. However, when individual responses are considered, 6 patients in the verum group (19%) experienced a seizure reduction of 50% or more, compared with no patients in the placebo group. During the trial, only mild adverse events were reported in both the loreclezole and the placebo group, nor were any clinically relevant abnormalities seen in the haematological and biochemical analysis. The efficacy and safety of higher loreclezole plasma concentrations were studied in a long-term follow-up trial, the results of which are presented in the following article.

Adult↗
PubMedDate not supplied

Long-term evaluation of the efficacy and safety of loreclezole as add-on therapy in patients with uncontrolled partial seizures: a 1-year open follow-up.

The effect and safety of loreclezole were evaluated during a long-term follow-up trial targeting higher plasma concentrations than those of the preceding controlled trial. The result is better than in the double-blind trial, in which loreclezole doses were administered to reach plasma concentrations of 1-2 mg/l and 6/32 patients (19%) of the verum group experienced a seizure reduction of 50% or more. None of the 30 placebo-treated patients experienced a similar decrease. At the end of the double-blind trial, 56 patients (29 from the original loreclezole and 27 from the original placebo group) elected to participate in the open follow-up trial. After 12 months' add-on treatment with loreclezole, mean plasma concentrations of 5.53 and 5.97 mg/l for the original placebo and loreclezole group were measured and the median decreases in seizure frequency were -44% and -40. At these concentrations, 22/56 patients (39%) showed a seizure reduction of at least 50%.

Adult↗
PubMedDate not supplied

[Recent aspects of Parkinson therapy].

After a short summary of the leading symptoms, the neuropathological and the pathobiochemical findings in Parkinson's disease, the possibilities of pharmacological treatment are pointed out. The choice of the suitable medication depends on the stage and severity of the disorder and the leading symptoms. Medical side-effects and contraindications of the different antiparkinsonica must be considered. Problems of long-term medication especially of L-dopa are discussed. Examples of reasonable "combined therapies" are given allowing the attempt to reduce the L-dopa dose without losing treatment effectiveness. In addition to the pharmacological treatment and for special indications, surgical i.e. stereotactic manipulations, intensive physiosocial care, physiotherapy and logotherapy are very necessary.

Aged↗