[Fetal outcome following cesarean section in premature labor. Isthmocorpus longitudinal section or isthmian transverse section?]. / "Fetal outcome" nach Sektio bei der frühen Frühgeburt. Isthmokorporaler Längsschnitt oder isthmischer Querschnitt?

Little is known about the comparative safety of the isthmocorporal versus the low transverse uterine incision for Caesarean delivery of the very low birthweight infant. To address this question, the fetal outcome of 59 deliveries by isthmocorporal incision and 76 by low transverse incision were analysed. The incidences of a 5-min-Apgar score of 6 or lower and UA-pH were not significantly different. No correlation was evident between early intraventricular hemorrhage and type of incision. The number of neonatal deaths weighing less than 1000 g associated with vertical incision (27%) was lower than that associated with the low transverse incision (47%). Nevertheless the difference was not statistically significant. The decision for the type of incision should be made intraoperatively by an experienced surgeon. This factor is probably more important than the choice of a particular incision.

Tetanus toxin: primary structure, expression in E. coli, and homology with botulinum toxins.

A pool of synthetic oligonucleotides was used to identify the gene encoding tetanus toxin on a 75-kbp plasmid from a toxigenic non-sporulating strain of Clostridium tetani. The nucleotide sequence contained a single open reading frame coding for 1315 amino acids corresponding to a polypeptide with a mol. wt of 150,700. In the mature toxin molecule, proline (2) and serine (458) formed the N termini of the 52,288 mol. wt light chain and the 98,300 mol. wt heavy chain, respectively. Cysteine (467) was involved in the disulfide linkage between the two subchains. The amino acid sequences of the tetanus toxin revealed striking homologies with the partial amino acid sequences of botulinum toxins A, B, and E, indicating that the neurotoxins from C. tetani and C. botulinum are derived from a common ancestral gene. Overlapping peptides together covering the entire tetanus toxin molecule were synthesized in Escherichia coli and identified by monoclonal antibodies. The promoter of the toxin gene was localized in a region extending 322 bp upstream from the ATG codon and was shown to be functional in E. coli.

Screening for bacterial Fc-receptor activity on nitrocellulose membranes.

Fc receptors released from staphylococci and streptococci could be readily detected by direct cultivation of the bacteria on nitrocellulose membranes or by microfiltration of their culture supernatants. The nitrocellulose membranes used in both assays were subsequently treated with human immunoglobulin (Ig) G. The reactions of the Fc receptor with IgG could be demonstrated by use of the respective peroxidase-labelled antibodies against IgG. The resulting color formation, which indicated Fc-receptor activity of the bacterial culture, closely corresponded to the 125I-labelled IgG-binding reactivity.

Enzymatic hydrolysis of tetanus toxin by intrinsic and extrinsic proteases. Characterization of the fragments by monoclonal antibodies.

Enzymatic fragments of tetanus toxin were characterized by immunoblotting using a set of previously characterized antibodies (Ahnert-Hilger et al. (1983) and a set of novel antibodies. The selected antibodies recognized the light chain, fragment C (beta 1), and the complementary piece (beta 2) of the heavy chain when blotted on nitrocellulose. All toxin preparations contained intrinsic esteroprotease activity which became manifest in the presence of urea. The main split product was a fragment (MW 100 000) reacting with anti-fragment C and anti-beta 2 antibodies. Toxicity does not depend on this protease activity. Some crude preparations of tetanus toxin contain another split product (MW 47 000) which resembles fragment C. The main product of papain hydrolysis is fragment C, which appears as a double band under nonreducing conditions but is homogeneous when reduced. Chymotryptic digestion hydrolyses the heavy chain well but leaves the light chain largely intact. Tetanus toxin is very resistant against trypsin as compared with other proteases, although this enzyme splits numerous different links. Our data show the usefulness of immunoblotting with monoclonal antibodies in analytical work with tetanus toxin, and the relevance of intrinsic proteases.

Monoclonal antibodies against tetanus toxin and toxoid.

Monoclonal antibodies against tetanus toxin and its toxoid were produced by immunizing mice with toxoid or toxin. They were measured by an enzyme-linked immunosorbent assay (ELISA), by a toxin neutralization test in mice (in vivo prevention test), and by their ability to prevent binding of 125I-toxin to brain membranes or gangliosides (in vitro prevention test). Six monoclonal antibodies obtained by immunization with toxoid (anti-toxoid 1-6) were investigated in more detail. They belonged to IgG class 1. Three of them (anti-toxoid 1, 2 and 3) recognized both toxoid and toxin as well as fragment B and the light chain of toxin, but not fragment C. Two other antibodies (anti-toxoid 4 and 5) were directed against toxoid only. Neither of them prevented toxin action in vitro or in vivo. Anti-toxoid 6 recognized toxin, toxoid and fragment C, but not light chain, and prevented toxin action in vitro and in vivo. Immunization against toxin was initiated with a toxin-antitoxin complex and boosted with toxin. We studied six antibodies in more detail, all of IgG type 2. Their KD against 125I-tetanus toxin varied from 10(-9) to 10(-10) M. Anti-toxin 2 recognized toxin, toxoid, light chain and fragment B, but not fragment C. The others reacted with toxin, toxoid and fragment C, but not with light chain or fragment B. All of them prevented toxin action in vitro and in vivo. As calculated from the maximal extinction achieved in the ELISA, tetanus toxin combined with a maximum of two different antibody molecules from our set. Gel filtration data indicate that tetanus toxin reacts with monoclonal antibodies one by one. Compared with polyclonal antiserum, monoclonal antibodies yield flatter slopes in both in vitro and in vivo prevention tests. Thus, they cannot substitute for the polyclonal antibodies in clinical situations, and cannot be calibrated in international units.