Search

Although the positive inotropic response to alpha 1-agonists has been well documented, the mechanism is incompletely understood. In isolated papillary muscle of cat and rabbit, low physiological concentrations of phenylephrine (PE) (10(-9)-10(-7) M; 35 degrees C) under beta-blockade (propranolol 10(-6) M) and in physiological [Ca2+]o (1.25 mM), significantly increased peak twitch tension (TT) with typical unchanged or slightly prolonged twitch contraction duration. This typical response necessitated the presence of an intact endocardial endothelium (EE) since no inotropic response was observed at or below 10(-7) M PE in muscles where the EE had been damaged by 1 s exposure to 1% Triton X-100 prior to the first PE addition. After Triton-induced EE damage prior to the first PE addition, a direct myocardial inotropic response could be demonstrated, but this response required higher concentrations of PE (10(-6)-10(-3) M) and was significantly less pronounced than in muscles with intact EE. At elevated (2.5 mM) or high (7.5 mM) Ca2+, a concentration dependent inotropic response to PE could be induced at the higher concentrations of PE (10(-6) M or higher), but the inotropic response to low concentrations of PE (10(-7) M or below) was absent even in the presence of an intact EE. In papillary muscles with intact EE at physiological [Ca2+]o of 1.25 mM, the higher concentrations of PE (10(-6) M or higher) destroyed the EE. Indeed, after washing with fresh bathing solution following prolonged exposure to these high concentrations of PE, the baseline twitches resembled twitches in muscles where the EE had been experimentally damaged. Selective destruction of the EE by PE in these conditions with no morphological damage to the subjacent myocardium was confirmed on electron microscopy. A second concentration-response curve to PE was significantly depressed, shifted to the right and with no response at or below 10(-7) M PE. Subsequent successive curves were not significantly different from the second one. At the higher Ca2+ (2.5 mM or 7.5 mM), neither functional nor morphological evidence of damage to the EE was observed regardless of the PE concentration and exposure time; in some muscles EE damage did occur at high Ca2+, however, but only after multiple exposures to high PE each followed by abundant wash. At all concentrations of PE, the alpha 1-antagonist prazosin (10(-5) M) blocked the inotropic response regardless of [Ca2+]o and prevented morphological endothelial damage at 1.25 mM Ca2+.

The relationship between the presence of glycosaminoglycans (GAGs) and the morphology of the middle layer or mesoblast was examined by performing transmission electron microscopy of chicken blastoderms microinjected with GAG-degrading enzymes. The controls included microinjections with saline or trypsin, as well as solid-phase assays for proteolytic activity in commercially available GAG-degrading preparations. The results indicate that, in normal as well as in saline-injected blastoderms, middle-layer cells are rounded or cuboidal in shape, and are linked to each other by small intercellular junctions in the primitive-streak region. As they migrate laterally along the basal lamina, they appear as typical mesenchymal cells, being separated by large intercellular spaces and covered by cell processes. The removal of hyaluronate (by the microinjection of hyaluronidases) led to compaction of the middle-layer cells in the area lateral to the primitive streak. These cells lost their mesenchymal aspect and retracted their processes, and intercellular junctions were observed. The presence of proteolytic activity in the enzyme preparations did not interfere with the results. On the basis of the results obtained using this microinjection technique, we were able to confirm at the ultrastructural level that hyaluronate, due to its space-creating properties, promotes the detachment of ingressed primitive-streak cells and preserves the mesenchymal aspect of the middle layer during the lateral migration of single cells along the basal lamina. Whether the presence of hyaluronate is necessary to allow positioning of the mesoblast could not be inferred using our experimental procedure. We present evidence that this molecule, as well as having physicochemical properties, is also involved in the modulation of tissue interactions during gastrulation.

Acid mucopolysaccharides in the extracellular compartment of early chick blastoderms (16 h of incubation) were labelled with tritiated glucosamine and/or [35S]sulphate. The incorporation pattern was studied autoradiographically. Treatment with testicular hyaluronidase revealed a testicular hyaluronidase-sensitive fraction, mainly at the periphery of Middle Layer and Deep Layer cells, and a testicular hyaluronidase-resistant fraction, mainly at the ventral side of the Upper Layer. A biochemical analysis, utilizing chondroitinase ABC and nitrous acid, followed by cellulose acetate electrophoresis, demonstrated the synthesis of a non-sulphated fraction, i.e. hyaluronic acid and/or chondroitin, and a sulphated fraction, comprising two undersulphated components, i.e. chondroitin sulphate, and heparan sulphate or heparin. The appearance of different AMPS in specific areas of the early chick blastoderm is regarded as an early specialization of the extracellular compartment.

With a set of 17 bacteriophages specific for Streptococcus faecalis and a set of 7 bacteriophages specific for Streptococcus faecium 441 strains of S. faecalis and 53 strains of S. faecium were typed. The species identification was done by means of the API 20 STREP system. For S. faecalis 22 and for S. faecium 12 lysotypes were found. Among S. faecalis strains lysotype V6b was most common (27%), followed by the lysotypes XV (9,5%), XIII1 (7%), II1 (5,7%), and I1 (4,3%). These 5 lysotypes comprised 54% of all 441 strains. 21% of the strains of S. faecalis and 6 from 53 strains of S. faecium were untypable. Strains of S. faecium were most frequently isolated from faeces and in rare cases from urine. To the contrary 50% of the S. faecalis strains were isolated from urine. There was no correlation between special lysotypes and age of the patients or the source of specimen. The results of phage typing of several strains from one patient, and especially of strains from mothers and their newborns suggest the usefulness of the typing system to clarify epidemiological questions.

Among 262 strains of Salmonella typhi from an epidemic outbreak of typhoid fever in Baden-Württemberg in 1974 2 strains were isolated which were tetracyclin resistant and showed no reactions with the Vi testphages T, D6 and VII whilst all other strains belonged to lysotype A, subtype Tananarive. It turned out that the Tc resistance in both strains was caused by a fi- R plasmid which could be transfered to other S. typhi strains, to E. coli K12, S. paratyphi B, S. java and S. typhi-murium as well as from Tc resistant E. coli K12 back to S. typhi. The Tc R plasmid introduced in S. typhi, lysotype A, caused specific restrictions of typing phages T, D6 and VII. Also, the transfer of the plasmids to strains of S. paratyphi B and S. typhi-murium resulted in restrictions of a number of typing phages. Both plasmids had identical patterns of restriction. In this pattern the Tc R plasmid differed from those described in the literature.

1998 strains of Salmonella typhi-murium from two different regions of West-Germany were investigated according to their biotype and phagetype. 132 strains were isolated from sewage, 320 strains from animals and the others from human beings. 60 different phagetypes were found. The phagetype 49 occurred most often (11,9% resp. 10,3%). A correlation between biotype and phagetype could not be observed. Nearly every phagetype could be divided into several biotypes. However, only few biotypes prevaled. These comprised the biotypes 1, 10 and 17. The examination of the splitting of trehalose was useful in the biochemical differentiation. Concerning strains of animal origin it was remarkable that most strains from cattle resp. calves belonged to the phagetype 49. Among 145 strains from pigeons 95,9% could be classified as phagetype 2. With exception of 3 strains all the other strains from pigeons did not possess the O-antigen 5. The majority of the strains belonged to the biotype 8. All these strains could not split maltose.

Scanning electron microscopy was used to study the acute histopathological effects immediately after surgical implantation of a 2-channel electrode, and the chronic effects after long-term placement of the perscalar implant. This study with cats shows that an atraumatic implantation can be achieved and that the peripheral neural structures were retained although the hair cells degenerated and the spatial organization of the supporting cells was slightly changed. The population of hair cells outside the region of the implanted electrode was not affected.

The ventral surface of the deep layer of gastrulating quail and chick embryos was examined using scanning electron microscopy. On the basis of cell protrusions, three or four different cell types were recognized. Cells covered with microplicae were found in the caudal region of the germ and as a narrow band extending along the lateral and anterior borders of the area pellucida. Cells covered with microvilli were found in a horseshoe-shaped zone in the anterior part of the germ. Beneath the rostral end of the primitive streak, the flattened deep-layer cells exhibited intercellular ridges and few microvilli. This area was surrounded by cells that usually had extended microvilli. The pattern of these cell types is discussed in relation to the formation of the different tissues that compose the deep layer in gastrulating embryos.

Ninety-five group D streptococcal isolates from the feces of 95 healthy persons were compared with 157 group D streptococcal isolates from 38 patients of the surgical intensive care unit (sICU). The typing systems consisted of phage typing, enterococcinotyping and species differentiation. Strains isolated from fecal specimens showed high individuality (66 combination types) whereas strains from the sICU revealed strongly uniform types (32 combination types, three types comprised 83 isolates, i.e. 52.8%). Endogenous colonization was demonstrated by isolation of strains from different locations (throat, trachea, wounds, blood, urine, drains, catheters, and vaginal swabs) from the same patient, and routes of transmission of the same strains to several patients were traced. The combination of three systems revealed a good discrimination between isolates of fecal and extrafecal specimens. The investigation detected highly preferred types in strains of extrafecal origin which were rarely isolated from fecal specimens. This may indicate that only strains with special characters preferably were able to colonize extraintestinal sites.

Primitive streak stage chick blastoderms were cultured for 30 min on a medium containing tritiated glucosamine. Light microscope autoradiography revealed extracellular labeling, and pretreatment of the sections with testicular hyaluronidase suggested the glycosaminoglycan nature of the labeled products. After incorporation of the tritiated precursor, some blastoderms were transferred to a chase medium, and cultured for 30, 90, 210 min. The changes is distribution of the labeled testicular hyaluronidase-sensitive macromolecules during the chase experiment illustrated the ingression of cells in the primitive streak stage chick blastoderm. Grain density differences, resulting from the various chase periods, suggested the renewal of the testicular hyaluronidase-sensitive fraction.

Scanning electron microscopy (SEM) was used to investigate the surface architecture of human tympanic membranes. The morphology of the normal eardrum was compared with the surface structure of preserved tympanic membrane (allograft), fresh air-dried fascia temporalis and preserved calf jugular vein (xenograft). The role of the physical structure and composition of the extra-cellular matrix in the restoration of a tympanic graft is discussed.

Group D streptococci (n = 971, 4037 samples, 139 patients) were isolated from two intensive care units. Differentiation and typing revealed 6 species, 25 phage types, and 85 enterococcinotypes. Distribution of species showed strong differences especially concerning Enterococcus faecium which was rarely isolated from extraintestinal sites (5.9%). Phage typing was species specific and discriminated Enterococcus faecalis (n = 703 typable isolates, 19 phage types) and the other group D streptococci (n = 63 typable isolates, 6 phage types). Based on the production of enterococcines (15 indicator strains used) the isolates could be classified into 6 groups, one of which was further subdivided into 3 subgroups. Enterococcus faecalis ssp. liquefaciens (n = 618), phage type V6b (n = 596), and enterococcine group IVc (n = 568) were most common. The combined use of markers resulted in 187 combinations, which demonstrated the valuable properties of the system.