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D Mack

Publications and source records attributed to D Mack.

At least 55 records · Page 3Linked to original sources
PubMed1999

Characterization of the relationship between polysaccharide intercellular adhesin and hemagglutination in Staphylococcus epidermidis.

To determine whether a relationship exists between biofilm formation and hemagglutination in Staphylococcus epidermidis, 20 skin isolates and 19 prosthetic valve endocarditis isolates were characterized for biofilm formation, hemagglutination, and the presence of a 357-bp polymerase chain reaction product within icaA. A strong association existed between biofilm formation, which has been linked to strains that produce polysaccharide intercellular adhesin (PIA), and hemagglutination. Strains that produced biofilm were significantly (P<.001) more likely to mediate hemagglutination (16 biofilm-positive/hemagglutination-positive strains and 19 biofilm-negative/hemagglutination-negative strains) within the 39 clinical strains tested. In addition, Staphylococcus carnosus TM300, a biofilm-negative, hemagglutination-negative strain, carrying the ica operon-containing plasmid pCN27, produced significant biofilm on glass and mediated hemagglutination (>/=1/128). It was concluded that production of PIA and hemagglutination are strongly associated and that PIA, at least in part, mediates hemagglutination in S. epidermidis.

Adhesins, Bacterial↗
PubMed1999

Essential functional role of the polysaccharide intercellular adhesin of Staphylococcus epidermidis in hemagglutination.

Hemagglutination of erythrocytes is a common property of Staphylococcus epidermidis strains, which is related to adherence and biofilm formation and may be essential for the pathogenesis of biomaterial-associated infections caused by S. epidermidis. In three independent biofilm-producing, hemagglutination-positive S. epidermidis isolates, interruption of the icaADBC operon essential for polysaccharide intercellular adhesin (PIA) synthesis by Tn917 insertions led to a hemagglutination-negative phenotype. An immunoglobulin G fraction of antiserum to PIA greatly reduced hemagglutination. Purified PIA led to a 64-fold decrease of hemagglutination titers of these strains; however, it did not mediate hemagglutination by itself. These observations define PIA as the hemagglutinin of S. epidermidis or at least as its major functional component.

Adhesins, Bacterial↗
PubMed1999

Characterization of the importance of polysaccharide intercellular adhesin/hemagglutinin of Staphylococcus epidermidis in the pathogenesis of biomaterial-based infection in a mouse foreign body infection model.

The production of biofilm is thought to be crucial in the pathogenesis of prosthetic-device infections caused by Staphylococcus epidermidis. An experimental animal model was used to assess the importance of biofilm production, which is mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of a biomaterial-based infection. Mice were inoculated along the length of a subcutaneously implanted intravenous catheter with either wild-type S. epidermidis 1457 or its isogenic PIA/HA-negative mutant. The wild-type strain was significantly more likely to cause a subcutaneous abscess than the mutant strain (P < 0.01) and was significantly less likely to be eradicated from the inoculation site by host defense (P < 0.05). In addition, the wild-type strain was found to adhere to the implanted catheters more abundantly than the PIA/HA-negative mutant (P < 0.05). The reliability of the adherence assay was assessed by scanning electron microscopy. To exclude contamination or spontaneous infection, bacterial strains recovered from the experimental animals were compared to inoculation strains by analysis of restriction fragment length polymorphism patterns by pulsed-field gel electrophoresis. In vitro binding of the wild-type strain and its isogenic mutant to a fibronectin-coated surface was similar. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis of S. epidermidis experimental foreign body infection.

Abscess↗
PubMed1999

Characterization of Staphylococcus epidermidis polysaccharide intercellular adhesin/hemagglutinin in the pathogenesis of intravascular catheter-associated infection in a rat model.

Biofilm production is thought to be a crucial factor in the ability of Staphylococcus epidermidis to produce a biomaterial-based infection. A rat central venous catheter (CVC)-associated infection model was used to assess the importance of biofilm production, mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of intravascular catheter-associated infection. PIA/HA-positive S. epidermidis 1457 was significantly more likely to cause a CVC-associated infection (71 versus 14%, P < 0.03) resulting in bacteremia and metastatic disease than its isogenic PIA/HA-negative mutant. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis of S. epidermidis experimental CVC-associated infection.

Animals↗
PubMed1999

Conservative treatment of acute Ormond's disease.

Ormond's disease is a chronic inflammatory process of the retroperitoneum, which sometimes takes a very acute course. We report the case of a man with acute bilateral hydronephrosis. Diagnosis was based on typical criteria seen by magnetic resonance imaging, which made biopsy unnecessary.

Acute Disease↗
PubMed1998

Laparoscopic vs open repair of gastric perforation and abdominal lavage of associated peritonitis in pigs.

BACKGROUND: Laparoscopy is increasingly used in conditions complicated by peritonitis, e.g., peptic ulcer perforation. Of some theoretical concern is the capnoperitoneum, which may aggravate peritonitis and induce septic shock due to increased intraabdominal pressure and distension of the peritoneum. This animal study was devised to analyze the effectiveness of laparoscopic versus traditional open repair of gastric perforation and abdominal lavage for associated peritonitis. METHODS: To simulate gastric perforation, female Duroc pigs were subjects to standardized gastrotomy. Either 6 or 12 h after gastric perforation, the animals underwent either traditional open or laparoscopic repair of the gastric defect and peritoneal lavage. The subjects were divided into the following four groups: peritonitis for 6 h and open surgery (group I) or laparoscopic surgery (group II); peritonitis for 12 h and open surgery (group III) or laparoscopic surgery (group IV). After an observation period of 6 days, the surviving animals were killed. The main outcome criteria were survival, perioperative changes of hemodynamics suggestive for septic shock, bacteremia, and endotoxemia. RESULTS: There were no significant differences between group I and II. Mortality was 22% in group III, as compared to 78% in group IV (p = 0.045). In group IV, the incidence of perioperative bacteremia and plasma endotoxin concentrations were significantly higher than in group III. Concomitantly, decreased mean arterial pressure and systemic vascular resistance, and increased cardiac output suggested a higher incidence of septic shock in group IV. CONCLUSION: Critical appraisal of laparoscopic surgery is warranted in conditions associated with severe, longstanding peritonitis.

Animals↗
PubMed1998

Intra-articular empyema due to Staphylococcus caprae following arthroscopic cruciate ligament repair.

Staphylococcus caprae is a catalase-positive, coagulase-negative coccus that has been originally isolated from goat milk. We describe the first case of an intra-articular empyema caused by S. caprae in an immunocompetent patient following arthroscopic cruciate ligament repair. The patient recovered completely after debridement and antibiotic therapy with cefazolin and amoxicillin, respectively. This case demonstrates that this organism may rarely cause serious nosocomial infections in immunocompetent adults.

Adult↗
PubMed1998

Generalized transduction for genetic linkage analysis and transfer of transposon insertions in different Staphylococcus epidermidis strains.

Staphylococcus epidermidis phage 48 was used to efficiently transduce plasmid pTV1ts and a chromosomal Tn917 insertion M27 from S. epidermidis 13-1 to biofilm-producing clinical S. epidermidis isolates 1457, 9142, and 8400. The Tn917 insertion leading to the biofilm-negative phenotype of transposon mutant M10 was sequentially transduced to biofilm-producing S. epidermidis 1457 using S. epidermidis phage 48 and then, using the resulting biofilm-negative transductant 1457-M10 as a donor, into several unrelated biofilm-producing clinical S. epidermidis isolates using S. epidermidis phage 71. All resultant transductants displayed a completely biofilm-negative phenotype. In addition, S. epidermidis phage 71 was adapted to S. epidermidis 1457 and 8400, which allowed generalized transduction of transposon insertions in these wild-type strains. As Tn917 predominantly transposed into endogenous plasmids of all three strains used, an efficient system for chromosomal transposon mutagenesis was established by curing of S. epidermidis 1457 of a single endogenous plasmid p1457 by sodium dodecylsulfate treatment. After transduction of the resulting derivative, S. epidermidis 1457c with pTV1ts, insertion of transposon Tn917 to different sites of the chromosome of S. epidermidis 1457c was observed. Biofilm-producing S. epidermidis 1457c x pTV1ts was used to isolate a biofilm-negative transposon mutant (1457c-M3) with a chromosomal insertion apparently different from two previously isolated isogenic biofilm-negative transposon mutants, M10 and M11 (Mack, D., M. Nedelmann, A. Krokotsch, A. Schwarzkopf, J. Heesemann, and R. Laufs: Infect Immun 62 [1994] 3244-3253). S. epidermidis phage 71 was used to prove genetic linkage between transposon insertion and altered phenotype by generalized transduction. In combination with phage transduction, 1457c x pTV1ts will be a useful tool facilitating the study of bacterial determinants of the pathogenicity of S. epidermidis.

Blotting, Southern↗
PubMed1998

Paclitaxel arrests growth of intracellular Toxoplasma gondii.

Addition of paclitaxel (Taxol) at a concentration of 1 microM to Toxoplasma gondii-infected human foreskin fibroblasts arrested parasite multiplication. Division of the T. gondii tachyzoite nucleus was inhibited, leading to syncytium-like parasite structures within the fibroblasts by 24 h after infection and treatment of the cultures. By 4 days after infection and treatment of the cultures with paclitaxel, this inhibition was irreversible, since the arrested intracellular form was incapable of leaving the host cell, infecting new cells, and initiating the growth of tachyzoites with normal morphology. Specifically, when paclitaxel was added to infected cells for 4 days and then removed by washing and the infected, paclitaxel-treated cells were cultured for 4 more days, there were no remaining T. gondii organisms with normal morphology. Syncytium-like structures in the cultures that were infected and treated with paclitaxel for 8 days were similar in appearance to those in preparations of infected paclitaxel-treated fibroblasts that had been cultured for 24 to 48 h. Pretreatment of the tachyzoites for 1 h with paclitaxel followed by the removal of the paclitaxel by repeatedly centrifuging and resuspending the parasites in fresh medium without paclitaxel and then adding fresh medium prior to culture of the parasites with fibroblasts did not prevent their invasion of fibroblasts but did affect their subsequent ability to replicate within fibroblasts. Pretreatment of the fibroblasts with paclitaxel also diminished subsequent replication of T. gondii in such host cells after 8 days. Thus, paclitaxel alters the ability of T. gondii to replicate in host cells. Inhibition of parasite microtubules by such compounds at concentrations which do not interfere with the function of host cell microtubules may be useful for development of novel medicines to treat T. gondii infections in the future.

Animals↗
PubMed1997

Expression of three UDP-N-acetyl-alpha-D-galactosamine:polypeptide GalNAc N-acetylgalactosaminyltransferases in adenocarcinoma cell lines.

The levels of mRNA expression of three UDP-N-acetyl-alpha-D-galactosamine:polypeptide GalNAc N-acetylgalactosaminyltransferases (GalNAc-transferases) were quantified for human adenocarcinoma cell lines from pancreas, colon, stomach, and breast. Two of the GalNAc-transferases, GalNAc-T1 and GalNAc-T2, were expressed constitutively and at low levels in most or all cell lines examined. A third GalNAc-transferase, GalNAc-T3, was differentially expressed. Well-differentiated adenocarcinoma cell lines expressed high levels and moderately differentiated cell lines expressed lower levels of GalNAc-T3. Cell lines classified as poorly differentiated failed to express GalNAc-T3 mRNA at levels that could be detected by Northern blot analysis. Differential expression of the GalNAc-T3 protein was confirmed in these cell lines by Western blotting. We propose that glycosylation in tumor cell lines may be regulated in part by differential expression of GalNAc-transferases, and we suggest that GalNAc-T3 gene expression may be a molecular indicator of differentiated adenocarcinoma.

Actins↗
PubMed1997

Effect of active immunization against luteinizing hormone-releasing hormone on the androgen-sensitive Dunning R3327-PAP and androgen-independent Dunning R3327-AT2.1 prostate cancer sublines.

BACKGROUND: The objective of this study was to determine the effect of active immunization against LHRH on the growth characteristics and histology of subcutaneously implanted tumors of the androgen-sensitive Dunning R3327-PAP and androgen-independent R3327-AT2.1 rat prostate adenocarcinoma sublines. RESULTS: We herein demonstrate that 1) active immunization with an LHRH-diphtheria toxoid-conjugate (LHRH-DT) leads to the downregulation of gonadotropins and testosterone and consequently the atrophy of testosterone-dependent organs such as the testes, prostate, and androgen-sensitive Dunning R3327-PAP tumors, 2) growth inhibition of Dunning R3327-PAP tumors is caused by suppression of cell division rather than by an increase in cell death and is associated with an increase of the tumor stroma content, and 3) volume increase of the androgen-independent Dunning R3327-AT2.1 tumor is slightly but significantly reduced, indicating a local stimulatory LHRH loop within this tumor cell line.

Analysis of Variance↗
PubMed1997

Eye manifestations of congenital toxoplasmosis.

PURPOSE: To determine the natural history of treated and untreated congenital toxoplasmosis and impact of this infection on vision. METHODS: In this prospective, longitudinal study, 76 newborns were treated with pyrimethamine and sulfadiazine for approximately one year, and 18 individuals not treated during their first year of life entered the study after age 1 year (historical patients). RESULTS: Chorioretinal scars were the most common eye finding in all patients and were most common in the periphery (58% of treated and 82% of historical patients). Macular scars were present in 54% of the treated patients; 41% were bilateral. Macular scars were present in 76% of the historical patients; 23% were bilateral. Visual acuity in the presence of macular lesions ranged from 20/20 to 20/400. Of the patients followed up from the newborn period and treated, 29% had bilateral visual impairment, with visual acuity for the best eye of less than 20/40. Causes for this visual impairment in eyes with quiescent lesions included macular scars, dragging of the macula secondary to a peripheral lesion, retinal detachment, optic atrophy, cataract, amblyopia, and phthisis. There were recurrences in both treated (13%, 7/54) and previously untreated historical patients (44%, 8/18). The total, median, and range of years of follow-up during which recurrences were observed were, for treated patients, 189 years (total), five years (median) and three to ten years (range) and, for historical, untreated patients, 160 years (total), 11 years (median), and three to 24 years (range). New lesions occurred in previously normal retinas and also contiguous to older scars. Active lesions appeared to become quiescent within ten to 14 days after beginning pyrimethamine and sulfadiazine therapy. CONCLUSION: Many children with congenital toxoplasmosis have substantial retinal damage at birth and consequent loss of vision. Nonetheless, vision may be remarkably good in the presence of large macular scars. Active lesions become quiescent with treatment.

Adolescent↗