Biomedical subjects
Publications and source records attributed to T Hofstad.
Clostridium difficile isolates from children with haematological malignancies, diarrhoea and healthy neonates as well as standard strains were examined by API ZYM (standard test) system and API ZYM research kit for glucosidases and peptidases. The results of expanded enzymatic characterization are presented.
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Lipopolysaccharide of Fusobacterium nucleatum strain Fevl was split by acid hydrolysis. The split products, i.e. lipid A and degraded polysaccharide were mitogenic for murine spleen cells as measured by uptake of [3H]thymidine. The uptake of [3H]thymidine was dose-dependent. Incubation of spleen cells with stimulants for 3 days resulted in a polyclonal activation of immunoglobulin synthesis. Higher mitogenic response and immunoglobulin production were found in spleen cells of athymic mice compared to those of thymic mice. The activity of lipid A in stimulating immunoglobulin synthesis was comparable with the parent lipopolysaccharide-Fevl, the degraded polysaccharide being the less potent stimulator.
A clone of serogroup A Neisseria meningitidis recognized by multilocus enzyme electrophoresis and designated as clone III-1, has caused major epidemics of meningococcal disease in various parts of the world since the 1970s. In Norway, serogroup B meningococci have been responsible for an epidemic since the mid-1970s. We have studied a sample of 53 meningococci isolated from patients in western Norway prior to the serogroup B epidemic. 22/35 meningococcal isolates collected 1969-73 represented clone III-1, whereas this clone was not found in the 18 isolates from 1962-68. It has been speculated that the epidemic of meningococcal disease in Finland caused by clone III-1 in 1973-75 had spread from an epidemic in USSR that began in 1969. Our findings demonstrate, however, that the clone III-1 was present in Scandinavia in 1969.
The immunochemical reactions of rabbit polyclonal antibodies directed to different preparations of Fusobacterium nucleatum i.e, whole cells, peptidoglycan associated proteins, a peptidoglycan-protein complex and a purified 40 kiloDalton (kDa) protein, were investigated on outer membrane preparations of Fusobacterium species and a restricted number of Leptotrichia buccalis after their separation on sodium dodecyl sulphate polyacrylamide gels and electrotransfer to nitrocellulose. All F. nucleatum strains had identical reaction patterns with the immune sera tested. Surface exposed parts of a restricted number of proteins with apparent molecular weights at 70 kDa (a doublet band), 60 kDa, 55 kDa and 40 kDa seemed to be major immunogens. Antigenic related proteins either of identical or slightly deviating electrophoretic mobilities to the 40-kDa protein were observed with the other members of Bacteroidaceae tested. The characteristic 70-kDa protein doublet seemed to be restricted to F. nucleatum although single protein bands of near identical molecular weights belonging to the other species tested also reacted. The data also indicate that the 60-kDa and 55-kDa polypeptides might be present in other species of Fusobacterium.
Eikenella corrodens was isolated from a posttraumatic liver abscess in a man with previous hemicolectomy for sigmoid adenocarcinoma. Escherichia coli was the initial isolate, but sepsis persisted after its eradication by cefuroxime and metronidazole. A second specimen yielded E. corrodens which responded promptly to combined ampicillin and netilmicin. The patient died of disseminated cancer 6 months later.
The literature dealing with adherence, host-protective mechanisms and tissues damaging products of nonsporeforming anaerobes is reviewed. The adherence mechanisms are poorly understood. There is evidence for that encapsulation plays a role in the pathogenicity of Bacteroides fragilis and black-pigmented bacteroides. A leukocidin is produced by Fusobacterium necrophorum, and Ig protease, collagenase and a trypsin-like enzyme by some Bacteroides species. Some Bacteroides fragilis strains produce an enterotoxin. The pathogenetic role of endotoxin is unclear.
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The outer membrane SDS-PAGE pattern of Eubacterium plautii was characterized by a large number of surface exposed low- and high-molecular-mass proteins. Silver stainable carbohydrate was not present. The pattern was clearly distinct from those of outer membrane preparations of Eubacterium saburreum and Fusobacterium nucleatum. The results are compatible with a Gram-positive cell wall structure in E. plautii.
The adhesion of Campylobacter jejuni and C. coli to isolated porcine intestinal brush border membranes was studied by phase-contrast and electron microscopy. Approximately 45% of the cell population adhered to the brush borders, possibly in a specific manner. Pretreatment of the brush borders with trypsin or pronase, and competitive inhibition with L-rhamnose caused a slight reduction of the adhesion. Different forms of pretreatment of the bacterial cells reduced their ability to adhere, but also their motility.
The polysaccharide antigen of Eubacterium saburreum strains L76, reacting by precipitation and complement-fixation, has D-glycero-D-galacto-heptose as the main component, and, in addition, O-acyl groups.
In 90 women with a norgestrel-releasing IUCD inserted and 50 women having a copper releasing IUCD, culturing of cervical and vaginal secretion was performed prior to, and 3 and 12 months after insertion of the IUCD. There were no significant changes in the cervical or vaginal microflora, and no significant differences between the groups. According to these findings, locally released progestogens from an IUCD do not affect the microflora of the vagina or of the cervix.
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Lipopolysaccharides (LPSs) were extracted by phenol-water from three oral strains of Selenomonas. The preparations were tested for the ability to induce a blastogenic response in cultures of spleen cells from normal and nude BALB/c mice, to activate guinea pig complement and the clotting enzyme system of Limulus polyphemus amoebocytes, and to kill Actinomycin-D treated mice. The capacity of the three LPSs was comparable to that of enterobacterial LPS.
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Shwartzman's reaction was elicited in four Chinchilla rabbits. Two of the animals were tranquillized with fentanyl-fluanisone (Hypnorm: Janssen Pharmaceuticals). There was a reduced response in the tranquillized rabbits while the untranquillized animals developed the typical dose-responsive skin reaction. Fentanyl-fluanisone tranquillization may interfere with the development of the Shwartzman reaction in Chinchilla rabbits.
Fatty acids of 16 strains of Selenomonas isolated from the human oral cavity were examined by gas-liquid chromatography. The strains showed similar patterns, characterized by the presence of straight-chain fatty acids in the range C11 to C18. Fatty acids of odd-numbered carbon atoms dominated and the major acids were n-pentadecanoate and 3-hydroxytridecanoate. The general fatty acid pattern of Selenomonas differed distinctly from those of other previously analysed anaerobic or microaerophilic Gram-negative bacilli.
Lipopolysaccharides (LPS) from Leptotrichia buccalis, strains L11, ATCC 14201 and ATCC 19616 were partially degraded with 1% acetic acid. The acid soluble polysaccharides were subjected to gel filtration. These experiments showed that the carbohydrate moiety of LPS from ATCC 14201 and ATCC 19616 were similar, consisting of a core oligosaccharide unsubstituted by 0-side chains containing galactose, glucose and D-glycero-D-manno-heptose as neutral sugars. The core analogous fraction isolated from L11 LPS contained the same three neutral sugars, but in different ratios.