From the group B streptococcus (GBS) reference strain 090 la Colindale two subpopulations, which differed markedly regarding their capacities for biosynthesis of type-specific polysaccharide, were obtained by separation on a hypotonic Percoll density gradient. In the original strain and the high and low density variants, there was a negative correlation between buoyant density and bio-synthesis of type-specific polysaccharide as determined by ultrastructure and quantitative assays. The invasiveness of these variants was investigated by infecting rabbits via subcutaneously implanted tissue cages. In the animals infected with highly encapsulated bacteria, heavy bacteremia was detected 8 h post-infection, whereas in the animals which received high density bacteria with small amount of capsule, heavy bacteremia was not detected until after five days. All isolates recovered from the blood or organs of these rabbits were of the capsule rich phenotype, indicating a phenotypic shift in the subpopulation of high density bacteria. An apparently similar phenotypic shift was noted in an isolate from a baby with early onset septicemia. There was a dominance of low density bacteria in the isolate obtained from the baby as compared with the colonizing population of bacteria isolated from the cervix of the mother. From these type III isolates, subpopulations with different density maxima were obtained. A reversed shifting towards dominance of less encapsulated, high density bacteria was observed during in vitro passage of these subpopulations.

Animals↗

PubMed1988

Effect of vitamin E deficiency on neurologic function in patients with cystic fibrosis.

We evaluated neurologic function in 18 patients, ages 5 to 26 years, with cystic fibrosis. Eight were deficient in vitamin E. Sural nerve conduction latency was increased and nerve action potential amplitude decreased in the vitamin E-deficient group in comparison with the vitamin E-sufficient group. Two vitamin E-deficient patients had absent deep tendon reflexes; findings of clinical neurologic examinations were otherwise normal. We recommend early supplementation with vitamin E for patients with cystic fibrosis who have pancreatic insufficiency, to prevent neurologic dysfunction.

Action Potentials↗

PubMed1988

Investigations on the binding of erythrogenic toxin A of Streptococcus pyogenes on human peripheral blood lymphocytes. II. Identification of toxin-binding lymphocytes and characterization of the receptor.

Gold complexes of erythrogenic toxin A (ETA) of Streptococcus pyogenes (strain NY-5) were bound to human lymphocytes that could be characterized as T cells by rosetting or labelling with OKT 3 antibody and anti-mouse-IgG-gold. Using OKT 4 and OKT 8 antibodies, respectively, it was demonstrated that binding of ETA was confined to the T helper/inducer cell subpopulation. Treatment of lymphocytes with neuraminidase enhanced the binding of ETA-gold, whereas trypsin treatment resulted in its reduction. Gangliosides of type II or type III and D-galactose only slightly decreased the ETA-gold binding. Preincubation of living lymphocytes with the mitogens concanavalin A or the Lens culinaris-lectin enhanced the binding of ETA-gold.

Bacterial Proteins↗

PubMed1988

Localization and characterization of fibronectin-binding to group A streptococci. An electron microscopic study using protein-gold-complexes.

The location and nature of the binding sites for fibronectin (Fn) and its N-terminal 29 K fragment (FnF) on group A streptococci were studied by electron microscopy using these proteins labelled with colloidal gold. The investigated strains exhibited a different labelling intensity as well as a different labelling pattern varying from a strong regular distribution to a weak focal binding. Binding of Fn and FnF was inhibited by itself as well as by lipoteichoic acid (LTA), anti-LTA and concanavalin A. Simultaneous labelling of the bacteria with marker complexes of FnF, human serum albumin and fibrinogen revealed separate receptor sites for each protein. Our results confirmed LTA to be mainly responsible for the binding of Fn on group A streptococci.

Binding Sites↗

PubMed1988

Electron microscopic localization of lipoteichoic acid on group A streptococci.

The location of lipoteichoic acid (LTA) on the surface of group A streptococci was studied by immunoelectron microscopic and ultrastructural cytochemical methods, i.e. by means of LTA antibodies labelled with ferritin, or concanavalin A labelled with ferritin or colloidal gold. All these methods proved the LTA to be located on the outer cell surface of most group A streptococcus strains. The differences in the intensity of labelling paralleled the hydrophobicity of the strains, being substantially higher in the strains exhibiting a high degree of hydrophobicity. Treatment of streptococci with pronase or trypsin led to a complete loss of surface-located LTA. On the other hand, pepsin treatment of streptococci under mild conditions resulted in an increased amount of surface-located LTA in some strains. On the isolated cell walls, LTA could be demonstrated only on the outer surface of the walls. These findings correlated well with the presumed role of group A streptococcus LTA in the adherence of streptococci to the epithelial cells which is accomplished with the aid of surface-located LTA molecules.

Bacterial Adhesion↗

PubMed1988

Immuno-electronmicroscopic demonstration of capsules on group-B streptococci of new serotypes and type candidates.

The location of type polysaccharides on the cells of reference strains of group-B streptococci of serotypes IV and V and new type candidates NT6 and 7271 was investigated by electronmicroscopy of the bacteria after incubation with homologous type-specific antiserum. A distinct capsular layer was found on the surface of the cells of all these strains. Sialic acid, an integral part of all the conventional type polysaccharides of group-B streptococci, was also detected in all the strains examined.

Immunologic Techniques↗

PubMed1988

Ligamentum flavum: appearance on sagittal and coronal MR images.

The appearance of the ligamentum flavum on sagittal and coronal magnetic resonance (MR) images has not been described in detail in the radiologic literature. The authors reviewed correlative MR images and anatomic sections obtained with a cryomicrotome in 20 cadavers in order to analyze anatomic relationships, variations, and progressive degenerative changes of the ligamentum flavum in the lumbar region. MR imaging showed the ligamentum flavum as an intermediate-signal-intensity structure on images obtained with short and long repetition times (TRs). Sagittal short TR images were effective for evaluating relationships between the ligamentum flavum, spinal canal, and nerve roots. Degenerative changes in the ligamentum flavum appeared as changes in shape or thickness of the ligaments on MR images. Calcification and fat infiltration, which were well depicted on anatomic sections, were not visualized on MR images.

Cadaver↗

PubMed1988

Progressive and regressive changes in the nucleus pulposus. Part I. The neonate.

Magnetic resonance (MR) imaging, correlated with anatomic sections, was used to characterize the progressive and regressive changes in the nucleus pulposus in neonates. The spines of five fetuses and five full-term infants between 16 and 40 weeks old were studied. In anatomic sections, the nucleus pulposus was sharply demarcated from the anulus fibrosus, Sharpey fibers were conspicuous, and a plate of primitive notochord was evident in the equator of the disk. On long repetition time (TR)/long echo time (TE) or long TR/short TE MR images, Sharpey fibers (low signal intensity) and notochord (low signal intensity) could be differentiated from the high-signal-intensity nucleus pulposus and anulus fibrosus. The major differences between the fetal and infant spines were the amount of notochord in the disk and ossification in the vertebral body.

Cadaver↗