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Biomedical subjects

I Just

Publications and source records attributed to I Just.

108 records · Page 6Linked to original sources
PubMed1989

ADP-ribosylation of actin causes increase in the rate of ATP exchange and inhibition of ATP hydrolysis.

ADP-ribosylation of skeletal muscle actin by Clostridium perfringens iota toxin increased the rate of exchange of actin-bound [gamma-32P]ATP by unlabelled ATP about twofold. Increased exchange rates were observed with ATP and ATP[gamma S], much less with ADP but not with AMP or NAD. ADP-ribosylation of skeletal muscle actin reduced "basal" and Mg2+ (1 mM)-induced ATP hydrolysis by about 80%. Similar inhibition of ATP hydrolysis was observed with liver actin ADP-ribosylated by Clostridium botulinum C2 toxin. The data indicate that ADP-ribosylation of actin at Arg-177 largely affects the ATP-binding and ATPase activity.

ADP Ribose Transferases↗
PubMed1989

Influence of botulinum C2 toxin on F-actin and N-formyl peptide receptor dynamics in human neutrophils.

Stimulation of human neutrophils with the chemotactic N-formyl peptide causes production of oxygen radicals and conversion of monomeric actin (G-actin) to polymeric actin (F-actin). The effects of the binary botulinum C2 toxin on the amount of F-actin and on neutrophil cell responses were studied. Two different methods for analyzing the actin response were used in formyl peptide-stimulated cells: staining of F-actin with rhodamine-phalloidin and a transient right angle light scatter. Preincubation of neutrophils with 400 ng/ml component I and 1,600 ng/ml component II of botulinum C2 toxin for 30 min almost completely inhibited the formyl peptide-stimulated polymerization of G-actin and at the same time decreased the amount of F-actin in unstimulated neutrophils by an average of approximately 30%. Botulinum C2 toxin preincubation for 60 min destroyed approximately 75% of the F-actin in unstimulated neutrophils. Right angle light scatter analysis showed that control neutrophils exhibited the transient response characteristic of actin polymerization; however, after botulinum C2 toxin treatment, degranulation was detected. Single components of the binary botulinum C2 toxin were without effect on the actin polymerization response. Fluorescence flow cytometry and fluorospectrometric binding studies showed little alteration in N-formyl peptide binding or dissociation dynamics in the toxin-treated cells. However, endocytosis of the fluorescent N-formyl peptide ligand-receptor complex was slower but still possible in degranulating neutrophils treated with botulinum C2 toxin for 60 min. The half-time of endocytosis, estimated from initial rates, was 4 and 8 min in control and botulinum C2 toxin-treated neutrophils, respectively.

Actins↗
PubMed1988

Different types of ADP-ribose protein bonds formed by botulinum C2 toxin, botulinum ADP-ribosyltransferase C3 and pertussis toxin.

We attempted to characterize ADP-ribose-amino acid bonds formed by various bacterial toxins. The ADP-ribose-arginine bond formed by botulinum C2 toxin in actin was cleaved with a half-life of about 2 h by treatment with hydroxylamine (0.5 M). In contrast, the ADP-ribose-cysteine bond formed by pertussis toxin in transducin and the ADP-ribose-amino acid linkage formed by botulinum ADP-ribosyltransferase C3 in platelet cytosolic proteins were not affected by hydroxylamine. HgCl2 cleaved the ADP-ribose-amino acid bond formed by pertussis toxin in transducin but not those formed by botulinum C2 toxin or botulinum ADP-ribosyltransferase C3 in actin and platelet cytosolic proteins, respectively. NaOH (0.5 M) cleaved the ADP-ribose-amino acid bonds formed by botulinum C2 toxin and pertussis toxin but not the one formed by botulinum ADP-ribosyltransferase C3. The data indicate that the ADP-ribose bond formed by botulinum ADP-ribosyltransferase C3 differs from those formed by the known bacterial ADP-ribosylating toxins.

ADP Ribose Transferases↗
PubMed1986

[Blood culture: efficacy of the specimens for the analysis of bacteremia and sepsis].

The indication for examination of blood cultures is discussed. The evaluation of clinical information with respect to the underlying diseases demonstrated that in most cases a microbiological etiology was suspected. Mostly we obtained diagnosis like chill, septic shock or suspicion of nosocomial infection. In most cases the infection origin was related to the gastrointestinal tract or the genitourinary tract. The examination of different specimens yielded the blood culture bottle as the best medium for diagnosis of septicemia. The laboratory diagnostic procedure is briefly presented. The rate of positive results, the contamination rate and the interpretation are discussed.

Blood Specimen Collection↗
PubMed1984

Thymectomy and chronic relapsing experimental allergic encephalomyelitis in guinea pigs.

Chronic relapsing experimental allergic encephalomyelitis (EAE) was induced in young Dunkin Hartley guinea pigs by a single sensitization with guinea pig spinal cord homogenate. The effect of either newborn thymectomy or young adult thymectomy on the clinical course of chronic and relapsing EAE was studied and evaluated statistically by Student's t test. All the animals that underwent thymectomy showed a significant delay in the onset of the disease compared with control groups. In addition, in the young adult guinea pigs in which thymectomy was done, the incidence of clinical disease was decreased. No substantial differences, however, were observed in the severity of the disease and number of remissions or relapses between guinea pigs in which thymectomy was done and in which clinical symptoms developed and controls.

Animals↗
PubMed1984

[Listeriosis: case report and repetitorium].

Three cases of listeriosis are presented: The first patient was a 72-year-old man, who had an operative removal of a thymom one and a half year ago. In 1983 he developed polyradiculitis and was treated with cortison. Three months later he developed meningeal symptoms. In the cerebrospinal fluid 10(5) per ml Listeria monocytogenes could be isolated. Under treatment with chloramphenicol and gentamycin he was cured. The second case was a female 84-year-old patient, who suddenly developed drowsiness and meningism. In the cerebrospinal fluid Listeria in low concentration was isolated. In spite of therapy with penicillin G and gentamycin in high dosage the patient got centralnervous spasms and died on the second day. The third patient was a premature born infant (31. week of pregnancy) with shortness of breath and hydrocephalus, that was treated with ventriculo-peritoneal shunts on both sides. In her fourth month she got a shunt-defect; Listeria in low concentration was isolated out of the cerebrospinal fluid. Treated with gentamycin intrathecal and amoxycillin she was successfully cured. Epidemiology, pathogenesis and new knowledge about diagnosis and therapy of Listeria are presented.

Aged↗
PubMed1979

[A contribution to the stabilisation of the MVA-vaccine (author's transl)].

The titre of the MVA-vaccine remains constant at -20 degrees C with human serum albumin, sorbitol, Haemaccel, Rheomacrodex and cysteine within 8 month. At -20 degrees C the stability of the MVA-virus is equivalent to the Vaccinia-virus, stabilized by peptone and sorbitol. Storing the MVA-Virus at +4 degrees C, +20 degrees C for 8 month or at 27 degrees C for 4 weeks, 1% human serum albumin and 5% sorbitol preserves the virustitre best, but the stability of Vaccinia-virus with 5% peptone and 5% sorbitol can, however, not be obtained by the MVA-virus under these conditions.

Animals↗
PubMed1976

Biochemical classification of herpes simplex virus types 1 and 2, and of intermediate strains on the basis of different susceptibilities of thymidine kinase to thymidine analogues.

Herpes simplex virus (HSV) type 1 can be differentiated from HSV type 2 on the basis of the sensitivity to 2'-deoxythymidine-5'-monophosphate of thymidine kinase induced in primary rabbit kidney cells. Whereas thymidine kinase induced by five strains of HSV type 1 (TK 1) is stimulated by suitable concentrations of 2'-deoxythymidine-5'-monophosphate, thymidine kinase induced by eight strains of HSV type 2 (TK 2) is inhibited. On the other hand, TK 2 is strongly inhibited by 2'-deoxythymidine-5'-triphosphate and by 2-bromo-2'-deoxyuridine-5'-triphosphate. The investigation of TK induced by six freshly isolated strains of HSV cross-reacting in neutralisation tests revealed two strains which induced TK 1 and two strains which induced TK 2. Two other strains induced thymidine kinase, the activity of which under the influence of these thymidine analogues was between that of TK 1 and TK 2. The properties of thymidine kinase remained constant after cloning the virus and thus is a genetically fixed trait due to recombination which could well occur in vivo.

Bromodeoxyuridine↗
PubMed1975

Influence of double infections on the induction of thymidine kinase by UV-irradiated herpes simplex virus types 1 and 2 and pseudorabies virus.

Simultaneous infection of primary rabbit kidney cells with HSV type 1 TK+ and a TK- strain results in a mutual influence of both viruses on the induction of thymidine kinase (TK). TK+ virus has an enhancing and TK- virus a depressing effect on TK induction by a superinfecting TK+ virus. The enzyme induction depends on the ratio of multiplicities of both viruses. The mutual influence on TK induction depends further on the time of addition of the superinfecting virus: the effect of the second virus can still be observed when given 6 hours after primary infection. Identical phenomena can be observed using combinations with HSV type 2 or Pseudorabies viruses. The ability of HSV to induce TK is progressively inactivated with increasing the time of UV-irradiation. The depressing effect of a TK- strain and the stimulating effect of a TK+ strain on superinfecting TK+ strains is UV-sensitive: after 6 minutes of UV-irradiation neither inhibition nor stimulation of TK induction by a superinfecting TK+ strain can be observed. Infection by long-term (20 minutes) UV-irradiated TK+ strains results in a depression of TK induction by a superinfecting TK+ virus. Long-term irradiation of the TK- virus does not show this effect. Cytosine-arabinoside has no effect on the mutual influence of TK induction by TK+ and TK-strains; the phenomenon of mutual depression therefore has to be considered an early process.

Cell-Free System↗
PubMed1975

Regulation by thymidine monophosphate and other nucleotides of thymidine kinase activity in extracts from primary rabbit kidney cells infected by HSV types 1 and 2.

In an attempt to differentiate between thymidine kinase (EC.2.4.1.21) induced by herpesvirus hominis type I (TK I) and type 2 (TK2), the different susceptibilities to the modifying effects of some thymidine analogues proved to be useful criteria: (I)2'-deoxythymidine-5'-triphosphate (dThd-5'-PPP) inhibits TK 2 at a concentration of 0-125 mM by 90%, whereas TK I is inhibited at 4-03 mM by 50%. (2) 2'-deoxythymidine-5'-monophosphate (dThd-5'-P) competitively inhibits TK 2 at all concentrations tested. On the other hand, the direction of its effect on TK I is concentration dependent: at 500 mum it stimulates and at 8 mM inhibits TK I activity. During enzyme kinetic studies, TK I displays substrate inhibition which is reversed by dThd-5'-P. This result explains the stimulating effect of dThd-5'-P at 500 muM. This phenomenon suggests the existence on the enzyme molecule of a second binding site for dThd which mediates substrate inhibition and which can be occupied also by dThd-5'-P. After polyacrylamide gel electrophoresis of TK I, the stimulation by dThd-5'-P disappears, suggesting the separation of the second binding site from the catalytic centre.

Cell-Free System↗
PubMedDate not supplied

Rho GTPases as targets of bacterial protein toxins.

Several bacterial toxins target Rho GTPases, which constitute molecular switches in several signaling processes and master regulators of the actin cytoskeleton. The biological activities of Rho GTPases are blocked by C3-like transferases, which ADP-ribosylate Rho at Asn41, but not Rac or Cdc42. Large clostridial cytotoxins (e. g., Clostridium difficile toxin A and B) glucosylate Rho GTPases at Thr37 (Rho) or Thr35 (Rac/Cdc42), thereby inhibiting Rho functions by preventing effector coupling. The 'injected' toxins ExoS, YopE and SptP from Pseudomonas aeruginosa, Yersinia and Salmonella ssp., respectively, which are transferred into the eukaryotic target cells by the type-III secretion system, inhibit Rho functions by acting as Rho GAP proteins. Rho GTPases are activated by the cytotoxic necrotizing factors CNF1 and CNF2 from Escherichia coli and by the dermonecrotizing toxin DNT from B. bronchiseptica. These toxins deamidate/transglutaminate Gln63 of Rho to block the intrinsic and GAP-stimulated GTP hydrolysis, thereby constitutively activating the GTPases. Rho GTPases are also activated by SopE, a type-III system injected protein from Salmonella ssp., that acts as a GEF protein.

Bacterial Toxins↗