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Biomedical subjects

F Jacob

Publications and source records attributed to F Jacob.

At least 19 recordsLinked to original sources
PubMed1992

[Abscess of the atrium: a complication of central venous catheters].

A 27-year-old female patient was admitted for parenteral feeding and treatment of an acute episode of her steroid dependent Crohn's disease. An intravenous catheter was inserted, the tip being located in the right atrium. This central line was accidentally removed ten days later and replaced with another one also ending in the right atrium. The patient's condition improved over a four-week period. Thereafter, she suddenly became confused and complained of abdominal pain with contracture. She displayed renal failure, coagulation disorders, and decreased blood cell counts. This was followed by a septic shock requiring mechanical ventilation and adrenaline. Laparotomy failed to reveal a cause for the patient's condition. She improved and was extubated four days later. From then on, she had fever (39 degrees C) again. Her catheter was replaced, the tip of this third one being inside the superior vena cava. Staphylococcus epidermidis was obtained from the catheter tip, as well as from four consecutive blood cultures. Despite administration of three different antibiotics, the high fever persisted (40 degrees C). Finally, the occurrence of a systolic murmur led to the discovery, with cardiac ultrasonography, of a mobile right atrial abscess, which engaged into the tricuspid valve at every contraction. Surgery to remove this mass was rapidly carried out. The bacterium was the same as that which had been isolated from the catheter. The patient improved and was able to return home a fortnight later. The diagnosis and prevention of this complication is discussed. The tip of central venous catheter should not be kept inside the atrium.

Abscess↗
PubMed1992

[Bacteriological relationship between organ donor and recipient. A survey apropos of 100 brain dead patients].

The aim of the study was to evaluate the relationship between germs found in samples systematically taken in the organ donors and germs found in the corresponding recipients in the 8 post-operative days. The 100 brain-dead patients received oxacillin (2g every 4 hours) when the bacteriological samples were taken. 41% of the donors were germ carriers. The germs were mainly located in the respiratory track (Staphylococcus aureus meti-S (34%) and Hemophilus (29%)). Among the 86 patients harvested, 40 donors were germ carriers and gave 132 organs, 46 donors were not germ carrier and gave 151 organs. The comparison between these two groups showed no difference. Assessment of infection occurring in organ recipient in the 8 post-operative days (germ, location, evolution) showed no difference, whether organs were removed from germ carrier donors or no. Comparison between the germs found in germ carrier donors and those found in recipients with sepsis showed a similitude in three cases (2.2%). In the other cases, there is no relationship between the germs found in the donors and post-operative sepsis in the recipient.

Brain Death↗
PubMed1991

The mutation Lys234His yields a class A beta-lactamase with a novel pH-dependence.

The lysine-234 residue is highly conserved in beta-lactamases and in nearly all active-site-serine penicillin-recognizing enzymes. Its replacement by a histidine residue in the Streptomyces albus G class A beta-lactamase yielded an enzyme the pH-dependence of which was characterized by the appearance of a novel pK, which could be attributed to the newly introduced residue. At low pH, the kcat, value for benzylpenicillin was as high as 50% of that of the wild-type enzyme, demonstrating that an efficient active site was maintained. Both kcat. and kcat/Km dramatically decreased above pH 6 but the decrease in kcat./Km could not be attributed to larger Km values. Thus a positive charge on the side chain of residue 234 appears to be more essential for transition-state stabilization than for initial recognition of the substrate ground state.

Ampicillin↗
PubMed1991

The importance of the negative charge of beta-lactam compounds in the interactions with active-site serine DD-peptidases and beta-lactamases.

The interaction between various penicillins and cephalosporins the carboxylate group of which at C-3 or C-4 had been esterified or amidated and different penicillin-recognizing enzymes was studied. In general, our findings reinforced the common assumption that an anionic group at that position is necessary for the effective acylation of these enzymes. However, the relative activities of the modified beta-lactams as inactivators of the Streptomyces R61 DD-peptidase or as substrates of the Bacillus licheniformis, Streptomyces albus G and Enterobacter cloacae beta-lactamases did not fit a general scheme in which the intrinsic electronic and geometric properties of the beta-lactam compounds would be sufficient to explain their substrate or inactivator properties towards the various types of enzymes investigated.

Acylation↗
PubMed1991

Active-site serine mutants of the Streptomyces albus G beta-lactamase.

By using site-directed mutagenesis, the active-site serine residue of the Streptomyces albus G beta-lactamase was substituted by alanine and cysteine. Both mutant enzymes were produced in Streptomyces lividans and purified to homogeneity. The cysteine beta-lactamase exhibited a substrate-specificity profile distinct from that of the wild-type enzyme, and its kcat./Km values at pH 7 were never higher than 0.1% of that of the serine enzyme. Unlike the wild-type enzyme, the activity of the mutant increased at acidic pH values. Surprisingly, the alanine mutant exhibited a weak but specific activity for benzylpenicillin and ampicillin. In addition, a very small production of wild-type enzyme, probably due to mistranslation, was detected, but that activity could be selectively eliminated. Both mutant enzymes were nearly as thermostable as the wild-type.

Base Sequence↗
PubMed1991

Prion diseases in man.

Human spongiform encephalopathies (HSE) are uncommon neurodegenerative diseases of unknown etiology. Whilst numerous observations provide arguments for an infectious disorder mediated by an unconventional agent of the so-called prion-type, the recent discovery of predisposing allelic variants suggests that HSE might be considered as genetically linked diseases.

Animals↗
PubMed1991

[Value of hormonal treatment with triiodothyronine and cortisone in brain dead patients].

Brain death leads to substantial falls in the plasma levels of cortisol and tri-iodothyronine (T3). These alterations may be responsible for physiological instability in these patients, and impairment in donor organ function. A double-blind study was therefore designed to assess the possible improvement in metabolism and haemodynamic stability in brain-dead organ donors treated with T3 and cortisone. Forty adult brain-dead patients were randomly assigned to two groups, the patients of the treated group were given every hour, or half hour, 2 or 4 micrograms T3 and 100 mg hydrocortisone intravenously, and those of the placebo group normal saline. Both groups of patients received conventional management for brain-dead donors. The main assessment criterion was the haemodynamic course, appreciated by the Pasys, the CVP and the needs in dobutamine; the secondary criterion was the start, or worsening, of a metabolic acidosis, as judged by the pH, the level of arterial bicarbonate, and the needs in sodium bicarbonate. The two groups were comparable for age, sex, aetiology of brain death, the delay between brain death and the start of the experimental protocol, and the duration of this protocol. There were differences between the two groups, which were not statistically significant: improvement in haemodynamic profile (hormone group 9/20 versus placebo group 10/20); worsening in haemodynamic profile (2/20 vs 4/20); increased requirements in dobutamine (2/20 vs 4/20); decreased requirements in inotropic support (15/20 vs 13/20); mean dose of dobutamine (3.1 +/- 4.2 micrograms.kg-1 vs 2.5 +/- 3.8 micrograms.kg-1); metabolic acidosis (5/20 vs 5/20); mean bicarbonate dose (30.0 +/- 67.7 mmol vs 45.0 +/- 74.2 mmol); donors harvested (20/20 vs 18/20).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1990

Cloning, partial sequence, expression, and antigenic analysis of the filamentous hemagglutinin gene of Bordetella pertussis.

The gene coding for the filamentous hemagglutinin (FHA), one of the main factors involved in mediating adherence of Bordetella pertussis to ciliated host cells, was cloned in Escherichia coli, and the 3,500-base-pair nucleotide sequence encoding the amino-terminal region was determined. Molecular cloning, together with the characterization of recombinant FHA-related proteins produced in E. coli, revealed that the primary translation product is a protein of about 370 kilodaltons (kDa). The mature 220-kDa FHA polypeptide secreted by B. pertussis is most probably generated by proteolytic processing that eliminates a carboxy-terminal portion of about 150 kDa. The 1,087 amino-terminal residues of the predicted FHA sequence showed a number of remarkable features. Extensive homology to the Serratia marcescens and Proteus mirabilis hemolysin proteins was found between amino acids 91 and 205 of the FHA sequence, suggesting involvement of this FHA domain in host cell binding or secretion of FHA from B. pertussis. In addition, two regions containing repetitive amino acid sequences were identified. One region, extending from residues 382 to 664, was formed by six repeats, and a second, extending from residues 701 to 912, contained three repeats. The reactivities of several recombinant FHA-derived proteins with a panel of monoclonal antibodies identified at least four epitopes composing an immunoreactive domain present in the carboxy-terminal moiety of the mature FHA.

Adhesins, Bacterial↗
PubMed1979

Characterization of glycopeptides isolated from membranes of F9 embryonal carcinoma cells.

From cells of a nullipotential line of embryonal carcinoma was isolated a membrane fraction enriched in the cell surface F9 antigen. More than 40% of the radioactive fucose and galactose incorporated by cells into nondialyzable material was recovered in this membrane preparation, corresponding to an approximately 10-fold purification of the labeled material. Extreme heterogeneity of membrane glycoproteins labeled with these sugars was revealed by sodium dodecyl sulfate gel electrophoresis. Glycopeptides prepared by extensive pronase digestion of membranes labeled with fucose or galactose showed properties similar to those already described for fucose-labeled glycopeptides from whole cells. Namely, large glycopeptides eluted near the excluded volume of Sephadex G-50 column were the predominant glycopeptide species, while complex glycopeptides of molecular weight around 2500 were minor components. Therefore, these large glycopeptides, characteristic of embryonal carcinoma cells, are derived mainly from a variety of glycoproteins closely associated with the membrane system, most probably cell-surface membrane of the cells. The large glycopeptides were also significantly labeled with glucosamine, but only slightly with mannose; major components of mannose-labeled glycopeptides from the membranes were high-mannose glycopeptides of low molecular weight. Several experiments excluded the possibility that the larg glycopeptides are mucopolysaccharides, glycolipids or mucin-type glycoproteins with short oligosaccharide chains.

Animals↗
PubMed1979

Distinctive properties of fucosyl glycopeptides on human teratoma cells.

Fucose-labeled glycopeptides from four human teratoma cell lines of independent origin show similar elution profiles on Sephadex G-50 column chromatography. The fucosyl glycopeptides elute in two major regions: one near the void volume, the other in fractions corresponding to a molecular weight of 2500-3000. These elution profiles are very different from those obtained with the other human cell lines examined which included 3 lymphomas, 2 colon carcinomas, and HeLa. The elution profiles of the human teratomas, however, show remarkable similarities to those obtained with murine embryonal carcinoma cell culture and early mouse embryos. These results suggest that the excluded G-50 fraction may well contain glycopeptides playing a role in mammalian embryogenesis.

Carcinoma↗
PubMed1979

Tropomyosin synthesis accompanies formation of actin filaments in embryonal carcinoma cells induced to differentiate by hexamethylene bisacetamide.

Hexamethylene bisacetamide (HMBA) induces in vitro the cytodifferentiation of PCC3/A/1 mouse embryonal carcinoma (EC) cells. In EC cells, actin is associated with surface structures but microfilament bundles are not seen. After 2 days of HMBA treatment, rounded EC cells are converted to flat adhesive ones with a developed cytoskeleton containing actin and tropomyosin. The ratio of actin to total proteins is constant in EC cells and their HMBA derivatives; but a striking difference is observed for one of the newly synthesized proteins (Mr 34,000) identified as tropomyosin. Synthesis of tropomyosin is followed by its association with actin microfilament bundles, as revealed by indirect immunofluorescence microscopy with specific antibodies.

Acetamides↗
PubMed1979

Junctional modulation in mouse embryonal carcinoma cells by Fab fragments of rabbit anti-embryonal carcinoma cell serum.

Mouse embryonal carcinoma PCC4 cells are connected by extensive gap and tight junctions. When the cells are incubated in a medium containing Fab fragments against embryonal carcinoma F9 cells, they round up and a process of junctional removal is initiated. In particular, gap junctions are internalized and after 30 hr of incubation with the anti-F9 Fab fragments both tight and gap junctions are no longer present at the cell surface; however, the cells are still in contact by means of small attachment sites.

Animals↗
PubMed1978

Association of the H-Y male antigen with beta2-microglobulin on human lymphoid and differentiated mouse teratocarcinoma cell lines.

The expression of the H-Y antigen has been tested on several human lymphoid lines and mouse teratocarcinoma cell lines during differentiation. The human male lymphoid cell line Raji is a very useful target for studies of the H-Y antigen by lymphocytotoxicity test with rat anti-H-Y sera. With a few exceptions, all cells carrying the Y chromosome were H-Y positive. One of the exceptions is the human Daudi cell line which, besides lacking H-Y antigen, also lacks beta2-microglobulin. We have studied a possible association between the H-Y antigen, beta2-microglobulin, and HLA antigen with redistribution experiments. The results strongly suggest that H-Y antigen is not associated with HLA antigens but with beta2-microglobulin.

Animals↗