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Biomedical subjects

S Krakowka

Publications and source records attributed to S Krakowka.

At least 55 records · Page 3Linked to original sources
PubMed1998

Antimicrobial therapies for Helicobacter pylori infection in gnotobiotic piglets.

Gnotobiotic piglets infected with Helicobacter pylori were treated with various antimicrobials as monotherapy and dual therapy, and the results were compared to those for piglets treated with a triple-therapy regimen (bismuth subsalicyclate at 5.7 mg/kg of body weight, metronidazole at 4.4 mg/kg, and amoxicillin at 6.8 mg/kg four times a day [QID]). Clearance of infection was assessed after 7 days of treatment, and eradication was assessed following 7 days of treatment and a 14-day posttreatment observation interval. Monotherapy with amoxicillin, clarithromycin, and ciprofloxacin cleared and eradicated the organism from porcine stomachs; monotherapy with metronidazole cleared the infection and eradicated it from some piglets. Metronidazole-resistant microbes were recovered from treated piglets which cleared but did not eradicate the infection. Monotherapy with bismuth subsalicylate, erythromycin, nitrofurantoin, and tetracycline in the dosage range of 5.0 to 7.1 mg/kg QID was less than 100% effective in clearance and eradication, in that these drugs cleared and/or eradicated the infection from some of the piglets but did not eradicate the infection from all of the piglets. Monotherapy with an H-2 receptor antagonist (ranitidine) or a proton pump inhibitor (omeprazole) was ineffective at either clearance or eradication. In vivo dose titrations with several effective monotherapies were performed to determine the lowest effective in vivo dose of drug. In piglets, eradication was associated with a statistically significant decline in serum H. pylori-specific immunoglobulin M (IgM) antibodies; the titers of both IgA and IgG also declined, but the values were not statistically significant. For many antimicrobials, piglets are more sensitive indicators of clearance and eradication than humans. These data establish the H. pylori-infected gnotobiotic piglet as a useful model for the identification of novel antimicrobials for the treatment of this disease and for drug assessment during preclinical evaluations.

Animals↗
PubMed1998

Production of gastroesophageal erosions and ulcers (GEU) in gnotobiotic swine monoinfected with fermentative commensal bacteria and fed high-carbohydrate diet.

Erosions and gastroesophageal ulcers (GEU) were produced in the pars esophagea of young gnotobiotic swine fed a carbohydrate-enriched liquid diet and monoinfected with two different fermentative commensal bacteria, Lactobacillus and Bacillus sp. In contrast, piglets, fed a similar diet and inoculated with Gastrospirillum sp. (Helicobacter heilmannii), a helicobacter species that colonizes the gastric mucosa, did not develop GEU. Experimental GEU likely develops secondary to epithelial damage mediated by microbial-origin acids whose production is potentiated by high dietary carbohydrate and parietal cell-origin hydrochloric acid.

Animals↗
PubMed1998

Experimental old dog encephalitis (ODE) in a gnotobiotic dog.

Experimental infection of a gnotobiotic Beagle dog with the neurovirulent R252 strain of canine distemper virus (R252-CDV) resulted in long-term central nervous system (CNS) infection; cerebral and brain stem lesions were consistent with old dog encephalitis (ODE). Eight clinical cycles of relapsing cortical and subcortical signs were documented over 33 months and were corroborated by the presence of both chronic and active inflammatory demyelinating lesions within the neuraxis. Immunocytochemistry revealed that CDV antigen was restricted to neurons. Attempts to use fresh brain tissue to directly transmit the infection to CDV-susceptible gnotobiotic dogs were unsuccessful. Reisolation of infectious virus from the infected dog required prolonged culture and coculture of brain explant cells with CDV-susceptible Vero cell monolayers. These findings demonstrate that ODE is a variant of virulent CDV-induced canine neurologic disease that can evolve de novo within the CNS of subclinically infected dogs in the absence of external sources of reinfection. The highly cell-associated nature of the virus, when first recovered from this dog, suggests that the virus was present within the CNS in a replication-defective form.

Animals↗
PubMed1997

Porcine gastric mucosa associated lymphoid tissue (MALT): stimulation by colonization with the gastric bacterial pathogen, Helicobacter pylori.

The presence and features of mucosa associated lymhoid tissue (MALT), analogous to Peyer's patches, in the cardia of the lesser curvature of the porcine stomach are described. The gastric mucosa associated lymphoid tissue (gastric-MALT) is histologically distinct from gastric inflammation associated with colonization by normal gastric microflora and experimental bacterial colonization with a human gastric bacterial pathogen, Helicobacter pylori. The gastric-MALT consists of well-demarcated encapsulated and organized lymphoid tissue, intimately associated with overlying gastric epithelium, centered below the muscularis mucosae and drained by efferent lymphatics. Gastric-MALT was identified in all piglets studied including microbially sterile uninfected gnotobiotes; these structures were enlarged with age and local (gastric) antigenic stimulation. Significant (P < 0.05) expansion of the gastric-MALT occurred in H. pylori-infected gnotobiotic piglets. These distinct morphologic features and location in the cardia suggest that lymphoid elements in the gastric-MALT are involved in gastric antigen processing and regional lymphoid maturation, differentiation and proliferation in the stomach.

Animals↗
PubMed1997

Inflammatory markers in bronchoalveolar lavage fluid of standardbred racehorses with inflammatory airway disease: response to interferon-alpha.

Protein and eicosanoid concentrations and procoagulant activity were determined in bronchoalveolar lavage fluid (BALF) from 32 Standardbred racehorses with inflammatory airway disease (IAD) and 6 control horses. Total protein, albumin and immunoglobulin G (IgG) concentrations were high (P < 0.05) in the BALF from horses with IAD, a finding consistent with exudation of plasma protein into the airway. Immunoglobulin A (IgA) concentrations also were increased (P < 0.05) which may signify local immunoglobulin production. Difference was not detected in prostaglandin E2 and 6-ketoprostaglandin F1 alpha concentrations in BALF of IAD-affected and control horses. Procoagulant activity was identified in the majority (66%) of BALF samples from IAD-affected horses and was not detected in control horses. Natural human interferon-alpha (nHulFN alpha) (placebo, 50, 150, or 450 units) was administered orally for 5 days to IAD-affected horses in a double-blind, randomised block design. Total protein, IgG, and IgA concentrations in BALF were reduced (P < 0.05) 8 days after administration of 50 u and 150 u nHuIFN alpha, and 15 days after administration of 50 u nHuIFN alpha. Procoagulant activity and albumin concentrations in BALF were lower 8 days after administration of 50 u nHuIFN alpha. Oral administration of low-dose nHuIFN alpha appeared to ameliorate these parameters of lower respiratory tract inflammation in Standardbred racehorses with IAD.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Role of vacuolating cytotoxin in gastritis due to Helicobacter pylori in gnotobiotic piglets.

To investigate the role of the Helicobacter pylori cytotoxin in the pathogenesis of gastritis, gnotobiotic piglets were colonized with either toxigenic H. pylori or a nontoxigenic isogenic mutant. Only piglets given the toxigenic strain developed toxin-neutralizing antibodies (indicating that toxin is expressed in vivo), but there was no difference in bacterial colonization, epithelial vacuolation, or gastritis between the two groups of piglets.

Animals↗
PubMed1996

Changes in airway inflammatory cell populations in standardbred racehorses after interferon-alpha administration.

Natural human interferon-alpha (nHuIFN alpha) was administered to actively training Standardbred racehorses with inflammatory airway disease (IAD). Inflammatory airway disease was characterized by poor exercise performance and inflammation and exudate in the upper and lower airway. Placebo, 50, 150, or 450 units(U) of nHuIFN alpha was administered orally for 5 consecutive days to eight horses per treatment group in a double-blind, randomized block design. Response to nHuIFN alpha was monitored by semiquantitative endoscopic examination score and cytologic examination of bronchoalveolar lavage fluid (BALF) performed at baseline (Day 1), Day 8 and Day 15 after initiation of nHuIFN alpha administration. Neutrophil, macrophage, lymphocyte, and nucleated cell counts in BALF were lower (P < 0.05), compared with BALF cell counts in placebo-treated horses 8 days after administration of 50 U and 150 U nHuIFN alpha, and 15 days after administration of 50 U nHuIFN alpha. Neutrophil, lymphocyte and nucleated cell counts were lower than cell counts from placebo-treated horses, 8 days following administration of 450 U nHuIFN alpha. The proportion CD4-, CD5-, and CD8-positive lymphocytes in BALF was not affected by administration of nHuIFN alpha. Oral administration of low-dose nHuIFN alpha reduced inflammation of the lowest respiratory tract in Standardbred racehorses with IAD.

Administration, Oral↗
PubMed1996

Manifestations of the local gastric immune response in gnotobiotic piglets infected with Helicobacter pylori.

Helicobacter pylori, a human gastric bacterial pathogen, was inoculated into gnotobiotic piglets and manifestations of the resultant gastric inflammation was analyzed by in situ immunochemistry and flow cytometric analysis of isolated lamina propria leukocytes (LPL) and peripheral blood leukocytes (PBL) recovered from infected and control piglets. Gastric mucosa tissue sections from uninfected control piglets were essentially negative for cluster differentiation- (CD-) positive leukocytes. Failure to isolate significant numbers of LPL from the gastric lamina propria confirmed this observation. A local and systemic immune response occurs in piglets after infection with H. pylori. This is manifest by the appearance of cells associated with a local immune response in gastric mucosa. In gastric tissue sections from H. pylori-infected piglets, CD4-positive leukocytes were sparse and closely associated with developing lymphoid follicles whereas the CD8-positive cellular phenotype was abundant. The latter formed a continuous band in the lamina propria just above the muscularis mucosa. Perivascular accumulations of lymphocytes in the outer muscular tunic(s) were strongly positive for expression of CD8 antigen. Class II-positive cells were prominent in CD8 lymphocytic infiltrates, developing follicles and vascular endothelia but were uniformly absent from gastric epithelia even in sites overlying areas of immunocyte proliferation and infiltration. Leukocytes possessing the monocyte and granulocyte markers were rare. Plasma cells containing IgA were common in the periphery of developing lymphoid follicles or distributed as discrete foci around individual gastric pits. Fewer numbers of IgG- and IgM-positive plasma cells were identified. When the LPL flow cytometry data were compared with the flow cytometry data obtained from PBL in these same H. pylori-infected piglets, leukocytes bearing the CD8 marker predominated in LPL whereas leukocytes bearing the CD4-reactive and MHC class II markers predominated in PBL. Finally, local ELISA antibody responses were measured in mucosal explant culture supernatants and compared with in vivo antibody levels in sera, bile, and gastric juice. Antibody activity, specific for H. pylori, was detected in supermatants and serum in all three isotypes in actively infected piglets whereas gastric juice lacked antibodies. Gastric explants prepared from piglets in which infection had been successfully eradicated failed to produce local antibody into supermatant fluids. These data support the concept that the gastric inflammation observed is mediated by local immunological events.

Animals↗
PubMed1996

Colonization of gnotobiotic piglets by Helicobacter pylori deficient in two flagellin genes.

Helicobacterpylori possesses two flagellin molecules, MA, the major species, and FlaB, which is expressed in minor amounts. This study sought to determine if one or both flagellin species are necessary for colonization or persistence by H. pylon. Thirty-six gnotobiotic piglets from six litters were given one of four isogenic strains of H. pylon orally. The bacterial strains used were strain N6, the wild type, which produced both FlaA and FlaB and was fully motile; N6flaB::km, which produced FlaA but not FlaB and was weakly motile; N6flaA::km, which expressed FlaB but not FlaA and was nonmotile; and N6flaA::cat/flaB::km, which produced neither flagellin and was nonmotile. Strain N6 colonized all piglets and persisted for 2, 4, and 10 days after inoculation. Both N6flaA::km and N6flaB::km colonized for 2 and 4 but not 10 days, and colonization was weak. N6flaA::cat/flaB:: km colonized for 2 days but did not persist for 4 or 10 days after inoculation. These findings demonstrate that both flagellin species are necessary for full colonization by H. pylon. Colonization for up to 4 days is possible in the absence of either flagellin species but not both.

Animals↗
PubMed1995

Oral treatment of transmissible gastroenteritis with natural human interferon alpha: a field study.

During a natural outbreak of transmissible gastroenteritis (TGE), groups of piglets were treated orally for 4 consecutive days with placebo or 1.0, 10.0 or 20.0 international units (IU) natural human interferon alpha (nHuIFN alpha). Piglets that were 1-12 days of age and given 1.0, 10.0 or 20.0 IU nHuIFN alpha had significantly (P < 0.01) greater survival rates than placebo-treated piglets; survival rates were the greater for the highest level of nHuIFN alpha treatment. In contrast, beneficial effects of nHuIFN alpha were not observed in piglets farrowed during the disease outbreak and given nHuIFN alpha within hours of birth. Oral nHuIFN alpha therapy modulates the natural course of high morbidity and mortality commonly seen with TGE.

Administration, Oral↗
PubMed1995

Metaphyseal bone lesions in young dogs with systemic canine distemper virus infection.

Bone lesions, restricted to the metaphyses of long bones, were observed in young dogs with systemic distemper following experimental and spontaneous infection. Canine distemper virus (CDV) antigen was found immunocytochemically in hematopoietic marrow cells, osteoclasts, osteoblasts and rarely in osteocytes. In experimentally infected dogs, viral antigen was demonstrated in the metaphysis between 5 and 36 days after infection. Associated lesions, characterized by necrosis of osteoclasts, persistence of primary spongiosa and atrophy and necrosis of osteoblasts and marrow cells, were mild and most prominent between 8 and 32 days postinfection. Metaphyseal osteosclerosis (MO) of the long bones, varying from mild to severe, was observed macroscopically in 8 (19%) out of 42 dogs with spontaneous distemper. Affected animals were between 3 and 6 months of age and belonged mainly to the large breeds. In these animals, MO was characterized histologically by persistence of primary spongiosa, loss of bone marrow cells and necrosis of osteoclasts and bone marrow cells varying from mild to severe. Summarized, CDV-associated bone lesions were only transient and there were no indications of viral persistence in bones of dogs experimentally infected with CDV. Although no clinical signs related to the bones were observed, the present study reveals that infection of metaphyseal bone cells is common in young dogs with systemic distemper and occurrence of viral antigen in these cells results in defects in bone modelling.

Animals↗
PubMed1995

Virulence of coccoid and bacillary forms of Helicobacter pylori in gnotobiotic piglets.

This study sought to determine if coccoid forms of Helicobacter pylori are virulent for gnotobiotic piglets. Coccoid forms were generated by maintaining broth cultures of H. pylori under microaerobic conditions for 16 days. The resulting cultures contained bacteria with a coccoid morphology that could not be cultured in vitro. Coccoid H. pylori did not colonize any of 6 gnotobiotic piglets that were inoculated, whereas bacillary H. pylori colonized 6 of 6 inoculated piglets. Piglets colonized by bacillary H. pylori developed lymphocytic gastritis, but no gastritis developed in piglets inoculated with coccoid H. pylori, and coccoid-inoculated piglets were sero-negative for H. pylori-specific antibody. Thus, coccoid H. pylori appears to be a degenerate nonviable morphologic phase.

Animals↗
PubMed1995

Occurrence of gastric ulcers in gnotobiotic piglets colonized by Helicobacter pylori.

Archival gastric tissues from 10 of 39 gnotobiotic piglets colonized with Helicobacter pylori 26695 contained stromal leukocytic inflammation along with ulcers and erosions. In contrast, gastric tissues from 54 archival control piglets were devoid of both inflammation and ulcers. These data confirm the hypothesis that H. pylori infection alone is ulcerogenic.

Animals↗
PubMed1995

An animal model of gastric ulcer due to bacterial gastritis in mice.

Conventional female BalbC mice were inoculated with Gastrospirillum-like bacteria in mouse gastric homogenate or in 5.0-microns filtrate of gastric homogenate. The bacteria were originally isolated from cheetahs with gastritis. The mice were killed 6 months, 7 months, or 1 year after inoculation. All mice became infected with Gastrospirillum-like bacteria that were confined to the gastric mucosa. Control mice, given either sterile Brucella broth, 0.22-microns filtrate of infected gastric homogenate, or uninfected gastric homogenate did not become infected with bacteria. Lesions in infected mice included severe lymphoplasmacytic gastritis (26/26 infected mice), gastric epithelial hyperplasia (25/26 infected mice), and gastric ulceration (11/26 infected mice). Neutrophilic inflammatory cell infiltrates were inconsistent. None of the uninfected control mice had Gastrospirillum-like bacteria, gastritis, gastric epithelial hyperplasia, or gastric ulceration. These results implicate Gastrospirillum-like bacteria from cheetahs in the pathogenesis of gastric ulceration. This model will be useful in investigating the mechanisms of gastric ulceration associated with bacterial gastritis.

Animals↗
PubMed1995

Histologic and immunocytochemical characterization of canine distemper-associated metaphyseal bone lesions in young dogs following experimental infection.

The proximal metaphyses of the humerus of weanling gnotobiotic dogs experimentally infected with canine distemper virus (CDV) were investigated histologically and immunocytochemically between 4 and 41 days after infection. Viral antigen was demonstrated in hematopoietic marrow and bone cells at postinfection day (PID) 5 and PID 7, respectively. Between PID 8 and 27, CDV antigen was abundantly present in marrow cells, osteoclasts, and osteoblasts and less frequently in osteocytes. Immunopositive cells in both osseous tissues and bone marrow declined between PID 29 and PID 36 and were absent by PID 41. Chondrocytes of the growth plate were negative for viral antigen throughout the observation period. In bone, viral antigen was more frequently observed in bone cells of the primary spongiosa than in the secondary spongiosa. There was a strong correlation between occurrence of CDV antigen and osseous changes. Associated metaphyseal bone lesions were mild and most prominent between PID 8 and PID 32. Lesions consisted of necrosis of osteoclasts, which was associated with subsequent persistence of the primary spongiosa (growth retardation lattice). Atrophy and necrosis of osteoblasts and marrow cells were also noted. Infection of metaphyseal bone cells appears to be common in young dogs with experimental systemic distemper. Bone cell infection is preceded by infection of marrow cells, and infected bone cells may experience degeneration and necrosis. This subtle viral effect may result in defects in bone modeling in CDV-infected dogs.

Animals↗
PubMed1995

Avirulent, urease-deficient Helicobacter pylori colonizes gastric epithelial explants ex vivo.

BACKGROUND: Urease-negative Helicobacter pylori generated by insertional mutagenesis fails to colonize gnotobiotic piglets, and this effect is largely independent of gastric pH. The purpose of this study was to determine whether urease-negative H. pylori colonized gastric explants ex vivo. METHODS: Gastric mucosal explants derived from neonatal germ-free piglets were inoculated with either wild-type H. pylori or one of two mutants derived by insertional mutagenesis. RESULTS: All three bacterial strains colonized explants. The level of colonization increased over the duration of the experiment, reaching 10(8)-10(9) cfu/g gastric mucosa by 72 h after inoculation. Morphologic evidence of colonization was similar to that observed in gnotobiotic piglets. CONCLUSIONS: Colonization of explants was not affected by lack of urease. These results contrast with previous findings showing that urease activity is essential for colonization of piglets by H. pylori. Thus, urease-dependent colonization is dependent on an intact gastric microenvironment.

Animals↗
PubMed1995

Cytologic evaluation of bronchoalveolar lavage fluid obtained from standardbred racehorses with inflammatory airway disease.

Cytologic examination of bronchoalveolar lavage fluid (BALF), including phenotypic analysis of lymphocytes, was performed on 32 Standardbreds with poor race performance and endoscopic examination findings characteristic of inflammatory airway disease (IAD). Nucleated cell counts in BALF from IAD-affected horses were higher than those in control horses; the cytologic profile of BALF in affected horses included mixed inflammation, characterized by mild neutrophilia, lymphocytosis, and monocytosis. Eosinophil and mast cell counts were not higher in the IAD-affected group, compared with those in the control group; however, 4 IAD-affected horses had marked eosinophilia (24.7 +/- 4.8% SEM) in BALF. Phenotypic analysis of lymphocytes in BALF obtained from IAD-affected horses revealed a low proportion of CD4-positive cells and B cells, compared with those in the control group; these findings may have been representative of a greater proportion of non-B, non-T cells (null cells) in horses with IAD. The cytologic profile of BALF obtained from horses with IAD differed from that in horses affected with chronic obstructive pulmonary disease, suggesting that the pathogenesis of inflammation in horses with IAD may differ from that of chronic obstructive pulmonary disease.

Animals↗