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Biomedical subjects

J G Fox

Publications and source records attributed to J G Fox.

At least 163 records · Page 9Linked to original sources
PubMed1995

Inability of an isogenic urease-negative mutant stain of Helicobacter mustelae to colonize the ferret stomach.

Eight ferrets specific-pathogen-free for Helicobacter mustelae were given, per dose, approximately 3.0 x 10(7) CFU of either the wild-type parent strain of H. mustelae (NCTC 12032) (two ferrets) the isogenic urease-negative mutant strain of H. mustelae (10::Tn3Km) (four ferrets), or sterile culture broth (two ferrets). Infection status was monitored by endoscopic gastric biopsy for urease activity, histopathology, and culture and by serology at 3, 6, 10, and 21 weeks. All ferrets were necropsied at 25 weeks. Both negative control ferrets remained uninfected, both ferrets receiving the H. mustelae wild-type parent strain became infected after two doses of the organism, and all four ferrets given two doses of the isogenic urease-negative mutant strain of H. mustelae remained uninfected throughout the 6-month study. Histopathology correlated with infection status. H. mustelae-infected ferrets exhibited diffuse mononuclear inflammation in the subglandular region and the lamina propria of the gastric mucosa, while uninfected ferrets showed no or minimal inflammation. These results suggest that urease activity is essential for colonization of the ferret stomach by H. mustelae.

Animals↗
PubMed1995

Identification of widespread Helicobacter hepaticus infection in feces in commercial mouse colonies by culture and PCR assay.

The identification of a new murine pathogen, Helicobacter hepaticus, and its association with chronic active hepatitis and liver tumors prompted an evaluation of the prevalence of H. hepaticus in commercially available mice. Of the 28 different strains or stocks, totaling 160 mice from four major commercial vendors, cultured for H. hepaticus, 100% of mice from two outbred strains from one vendor were infected with H. hepaticus, whereas 9 of 13 inbred mouse strains from another vendor were infected. This high prevalence of H. hepaticus established a need for a rapid and reproducible, noninvasive assay for the screening of colony-maintained mice being used for biomedical research. The culturing of fecal material by using 0.45-microns-pore- size filtration for H. hepaticus consistently yielded reproducible results but required extended periods of time. (1 to 3 weeks) to obtain a definitive answer. Although it is rapid, the use of a direct PCR-based detection assay with fecal specimens is restricted by inhibitory agents. to circumvent these inhibitory agents and to augment our H. hepaticus culture technique, we have developed a novel PCR system in which the bacteria are isolated from fecal material in the presence of polyvinylpyropyrollidone and lysed by treatment with Chelex 100. The PCR is performed with Tth polymerase supplemented with a polymerase enhancer. By this PCR method, 24 H. hepaticus culture-positive and 30 H. hepaticus culture-negative fecal samples were correctly identified. Moreover, two samples which were PCR positive and culture negative initially were positive by both methods upon retesting of fresh material. Southern blot hybridizations and sequencing of PCR products showed them to be H. hepaticus specific. A comparison of results obtained under identical conditions indicated a 100-fold increase in sensitivity with Tth polymerase over Taq polymerase. This PCR method can be used as a noninvasive means of rapidly screening large numbers of colony mice for H. hepaticus.

Animals↗
PubMed1995

Helicobacter bilis sp. nov., a novel Helicobacter species isolated from bile, livers, and intestines of aged, inbred mice.

A fusiform bacterium with 3 to 14 multiple bipolar sheathed flagella and periplasmic fibers wrapped around the cell was isolated from the liver, bile, and lower intestine of aged, inbred mice. The bacteria grew at 37 and 42 degrees C under microaerophilic conditions, rapidly hydrolyzed urea, were catalase and oxidase positive, reduced nitrate to nitrite, did not hydrolyze indoxyl acetate or hippurate, and were resistant to both cephalothin and nalidixic acid but sensitive to metronidazole. On the basis of 16S rRNA gene sequence analysis, the organism was classified as a novel helicobacter, Helicobacter bilis. This new helicobacter, like Helicobacter hepaticus, colonizes the bile, liver, and intestine of mice. Although the organism is associated with multifocal chronic hepatitis, further studies are required to ascertain whether H. bilis is responsible for causing chronic hepatitis and/or hepatocellular tumors in mice.

Aging↗
PubMed1995

Long-term colonization with single and multiple strains of Helicobacter pylori assessed by DNA fingerprinting.

The gastric pathogen Helicobacter pylori establishes long-term chronic infections that can lead to gastritis, peptic ulcers, and cancer. The species is so diverse that distinctly different strains are generally recovered from each patient. To better understand the dynamics of long-term carriage, we characterized H. pylori isolates from initial and follow-up biopsy specimens from a patient population at high risk of H. pylori infection and gastric cancer. Eighty-five isolates were obtained from 23 patients and were analyzed by genomic restriction enzyme analysis, arbitrarily primed PCR fingerprinting, (random amplified polymorphic DNA analysis), and/or restriction of specific PCR-amplified genes (restriction fragment length polymorphism analysis). A single strain was found in sequential biopsy specimens from 12 of 15 patients (80%) receiving sucralfate. In the remaining three patients treated with sucralfate, two strains were identified in two patients and three strains were identified in the third patient. In contrast, a single strain was found in sequential biopsy specimens from only three of eight patients (37%) receiving bismuth, metronidazole, and nitrofurantoin. Two strains were identified in five other patients receiving bismuth-antibiotic (63%). Immunoglobulin G antibodies to H. pylori were present in the sera of all patients. Thus, H. pylori colonization can persist for long periods (up to at least 4 years), despite high titers of immunoglobulin G antibodies in serum. Resistance to metronidazole was noted in some strains before and/or after treatment, but all strains remained susceptible to amoxicillin, tetracycline, and nitrofurantoin. We conclude that H. pylori genotypes, as measured by several sensitive DNA fingerprinting methods, can remain stable for years in vivo, despite the acquisition or loss of drug resistance, circulating antibody, or exposure to antibiotics or sucralfate.

Anti-Bacterial Agents↗
PubMed1995

Characterization of feline Helicobacter pylori strains and associated gastritis in a colony of domestic cats.

Twenty-four young adult domestic cats from a commercial vendor were found to be infected with Helicobacter pylori. Histopathologic analyses, selected electron microscopy, and urease mapping were performed on mucosal samples collected from the cardias and fundi, bodies, and antra of these cats' stomachs. H. pylori organisms were abundant in all areas of the stomach on the basis of histologic evaluation and urease mapping. H. pylori infection was associated with a moderate to severe lymphofollicular gastritis in 21 of 24 cats (88%). The gastritis was most pronounced in the antral region and consisted mainly of multifocal lymphoplasmacytic follicular infiltrates in the deep mucosa. The severity of gastritis in the antrum corresponded to high numbers of H. pylori there on the basis of the use of the urease assay as an indicator of H. pylori colonization. Ten of 24 cats (42%) also had small to moderate numbers of eosinophils in the gastric mucosa. All 24 cats had gastric lymphoid follicles, with follicles being most prevalent in the antrum. Electron microscopy of gastric tissue revealed numerous H. pylori organisms, some of which were closely adhered to the mucosal epithelium. Human H. pylori gene-specific primers to ureA and ureB amplified products of similar sizes from H. pylori cat isolates. Digestion of the products with restriction enzymes resulted in fragments characteristic of the restriction fragment length polymorphism patterns of H. pylori isolates from humans. In the domestic cat, H. pylori infection is associated with a lymphofollicular gastritis, consisting of lymphocytic and plasmacytic infiltration into the lamina propria, and the organism appears to provide chronic antigenic stimulation resulting in the formation of gastric lymphoid follicles.

Animals↗
PubMed1995

Detection of Clostridium difficile toxins from the small intestine and cecum of rabbits with naturally acquired enterotoxemia.

Four specific-pathogen-free rabbits with anorexia died peracutely; decreased fecal output, nasal exudate, and labored breathing were the only other clinical abnormalities observed in two of the rabbits before death. The animals, three juveniles and one adult, were on a standard polyclonal antibody production regimen and had received immunizations approximately 2 weeks before presentation. External examination revealed distended abdomen and perineal fecal staining. At necropsy the small intestine was distended with fluid, and the cecum was distended with chyme. The small intestines and cecum had marked serosal hyperemia. Anaerobic bacterial culture techniques were used to isolate Clostridium difficile from the small intestine (3/4) and cecum (2/4). In all cases C. difficile toxin B was detected at high titers (10(2) to > 10(5)) in the small intestine by cytotoxicity assay with HeLa 229 cell culture. In two of the four rabbits C. difficile was isolated, and cytotoxin titers were detected at 10(1) and 10(4) in the cecum of affected rabbits. Toxin B was neutralized with C. sordellii antiserum but not C. spiroforme antiserum. In addition, toxin A was detected in each of the cytotoxin B-positive samples by a commercial toxin A enzyme immunosorbent assay. In vitro production of toxins A and B was detected from each culture isolate after incubation in chopped meat broth. These cases are noteworthy because spontaneous (nonantibiotic-associated) C. difficile enterotoxemia has not been previously reported in rabbits. Also the toxins of clostridial organisms are usually documented in the cecum, not the small intestine, of rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Transmission of a chronic lymphoproliferative syndrome in ferrets.

BACKGROUND: Lymphomas and leukemias are caused by transmissible viruses in a wide variety of species, including humans, cattle, and cats. Features of lymphoma in ferrets suggest that it, too, may have an infectious etiology. No agent has been identified. EXPERIMENTAL DESIGN: Cells or cell-free inocula from a ferret with spontaneous malignant lymphoma were administered i.p. to six recipient ferrets. Two ferrets received fresh cells, two received frozen cells, and two received cell-free culture supernatant. The recipients were monitored routinely clinically and hematologically, and lymphoma was confirmed histologically. The lymphomas were characterized using cytology, cytochemistry, immunophenotyping, and histology. Cultivated cells from the donor and recipients were examined using reverse transcriptase assay, microscopy, and electron microscopy. RESULTS: All of the six recipient ferrets developed mild sustained lymphocytosis within 6 weeks of the inoculation. Two of six were euthanized 14 to 18 months after inoculation. Lymphoma was later diagnosed in three of the four remaining ferrets at 24 to 36 months after inoculation. All developed a chronic indolent syndrome featuring profound splenomegaly, lymphocytosis with atypia, and histologically polymorphous lymphoma. Two of the three who developed lymphoma had received fresh donor lymphoma cells, and the third had received supernatant from donor cell cultures with elevated reverse transcriptase activity. Cultivated cells from the affected ferrets demonstrated reverse transcriptase activity and retrovirus-like particles. CONCLUSIONS: This study demonstrates horizontal transmission of malignant lymphoma in ferrets using cell or cell-free inocula. Clinical and pathologic features of this syndrome in ferrets resembled virally induced lymphomas in other species.

Animals↗
PubMed1995

Non-human reservoirs of Helicobacter pylori.

Early attempts to identify non-human reservoirs for Helicobacter pylori were largely unrewarding. The one exception being old-world macaques, which were found to be colonized with H. pylori; however, it is doubtful whether this species provides an important reservoir for human infection. The possibility of other animal reservoirs and zoonotic transmission of H. pylori has been discussed, but until recently has not received serious study. Enthusiasm to initiate extensive studies in this area were further dampened by the inability to experimentally infect several different species of mammals with the organism. Reports using whole-cell enzyme-linked immunoabsorbent assay (ELISA) sonicate to monitor infection serologically, have cited a high incidence of H. pylori infection in abattoir workers. These results have been criticized because of potential antigenic cross-reactivity in workers' sera due to the constant exposure of these personnel to other gastrointestinal flora of animals. The large spiral gastric Helicobacter-like organisms (GHLOs) commonly noted in dogs and cats are associated with approximately 0.08-1% of gastritis in humans. These GHLOs often infect patients who own pets, suggesting a zoonotic link. Thus, the recent isolation of H. pylori from the inflamed gastric mucosa of commercially reared cats, and the ability to experimentally infect cats with H. pylori, raises the possibility of zoonotic H. pylori transmission from infected animals who have close human contact. Water and raw vegetables have been linked with H. pylori transmission in a few epidemiologically-based studies in developing populations. The recent isolation of H. pylori from the faeces of adults and children implicates a faecal-oral transmission pathway and supports the theory that both food and water (via faecal contamination) could be a source of H. pylori. Providing conclusive evidence that H. pylori has the ability to exist in the environment as a viable, non-culturable coccoid form that can replicate after ingestion by a mammalian host would considerably strengthen the hypothesis that water and food are important H. pylori reservoirs. The existence and extent of these reservoirs in nature, and the manner in which they interact with humans, will provide important new insights into understanding the epidemiology of this worldwide infection.

Adult↗
PubMed1994

Copper toxicosis in sibling ferrets.

Two sexually intact female silver-shaded domestic ferret siblings from different litters were examined because of CNS depression and lethargy. Ferret 1 was dehydrated and hypothermic, whereas ferret 2 was icteric and febrile and had serum bilirubin concentration > 12.0 mg/dl and BUN of 59 mg/dl. Despite supportive treatment, the ferrets died within days of evaluation. On necropsy, ferret 1 had chronic hepatopathy, with diffuse vacuolation of hepatocytes. In ferret 2, the liver had centrilobular degeneration and necrosis, and hemoglobinuric nephrosis was evident, with hemoglobin in the renal tubules. In both ferrets, Kupffer's cells and macrophages contained eosinophilic material in the cytoplasm. Special staining revealed copper pigment in hepatocytes and phagocytic cells in both livers. Analysis of liver specimens revealed 850 and 700 ppm of copper in ferrets 1 and 2, respectively. Copper values > 200 ppm in liver are considered evidence of toxicosis in most animal species. Copper toxicosis was diagnosed on the basis of the findings from histologic examination of the liver and high hepatic copper values. Lack of related illness in 11 other ferrets in the same environment and fed the same diet, plus sibling relationship and same phenotypic coat color in the affected ferrets, suggested that these ferrets had an inherited defect in their ability to metabolize normal amounts of ingested copper.

Animals↗
PubMed1994

Chronic active hepatitis and associated liver tumors in mice caused by a persistent bacterial infection with a novel Helicobacter species.

BACKGROUND: In the autumn of 1992, a novel form of chronic, active hepatitis of unknown etiology was discovered in mice at the National Cancer Institute-Frederick Cancer Research and Development Center (NCI-FCRDC), Frederick, Md. A high incidence of hepatocellular tumors occurred in affected animals. The disease entity was originally identified in A/JCr mice that were untreated controls in a long-term toxicologic study. PURPOSE: Our original purpose was to determine the origin and etiology of the chronic hepatitis and to quantify its association with hepatocellular tumors in mice of low liver tumor incidence strains. After a helical microorganism was discovered in hepatic parenchyma of diseased mice, we undertook characterization of the organism and investigation of its relationship to the disease process. METHODS: Hepatic histopathology of many strains of mice and rats, as well as guinea pigs and Syrian hamsters, in our research and animal production facilities was reviewed. Steiner's modification of the Warthin-Starry stain and transmission electron microscopy were used to identify bacteria in the liver. We transmitted the hepatitis with liver suspensions from affected mice and by inoculation with bacterial cultures. Bacteria were cultivated on blood agar plates maintained under anaerobic or microaerophilic conditions and characterized morphologically, biochemically, and by 16S rRNA sequence. RESULTS: We report here the isolation of a new species of Helicobacter (provisionally designated Helicobacter hepaticus sp. nov.) that selectively and persistently colonizes the hepatic bile canaliculi of mice (and possibly the intrahepatic biliary system and large bowel), causing a morphologically distinctive pattern of chronic, active hepatitis and associated with a high incidence of hepatocellular neoplasms in infected animals. CONCLUSIONS: The novel Helicobacter is a likely candidate for the etiology of hepatocellular tumors in our mice. The Helicobacter-associated chronic active hepatitis represents a new model to study mechanisms of carcinogenesis by this genus of bacteria. IMPLICATIONS: Adenocarcinoma of the stomach, the second most prevalent of all human malignancies world-wide, is associated with infection at an early age with Helicobacter pylori. Infection leads to several distinctive forms of gastritis, including chronic atrophic gastritis, which is a precursor of adenocarcinoma. H. hepaticus infection in mice constitutes the only other parallel association between a persistent bacterial infection and tumor development known to exist naturally. Study of the H. hepaticus syndrome of chronic active hepatitis and liver tumors in mice may yield insights into the role of H. pylori in human stomach cancer and gastric lymphoma.

Adenoma, Liver Cell↗
PubMed1994

Megaesophagus in nine ferrets.

Megaesophagus was diagnosed in 9 adult ferrets. Clinical history of the ferrets included regurgitation, difficulty in swallowing, partial anorexia, and lethargy. Cachexia, dehydration, weakness, and ptyalism were observed on physical examination. Radiography revealed the esophagus of each ferret to be dilated in the thoracic and cervical regions. Of 4 ferrets that had lymphocytopenia, 2 had concurrent leukopenia. Serum biochemical analysis revealed high activity of alanine transaminase (4 ferrets) and aspartate transaminase (3), and hypoglycemia (4). Treatment included administration of fluid, antibiotics, and agents directed against possible primary causes of megaesophagus. Treatments were ineffective, and all of the ferrets died or were euthanatized. All 6 ferrets that were submitted for necropsy had bronchopneumonia, hepatic lipidosis, mild esophagitis, and gastritis. The etiopathogenesis of megaesophagus in the ferrets was not determined.

Animals↗
PubMed1994

Genome conservation in Helicobacter mustelae as determined by pulsed-field gel electrophoresis.

Genomic DNA from 15 strains of Helicobacter mustelae was subjected to pulsed-field gel electrophoresis (PFGE) after digestion with PacI and SfiI. H. mustelae genome DNA appeared very similar in all strains examined, whether isolated from ferrets or mink or from animals bred in either the USA or in the UK. The H. mustelae genome size was estimated to be 1.7 Mb, similar in size to that of H. pylori. A minor difference in PacI PFGE pattern and genome size was observed between rifampicin-resistant and rifampicin-susceptible derivatives of H. mustelae F251. Another minor difference in genome pattern based on PFGE with SfiI was observed between an H. mustelae strain used to experimentally infect four ferrets which resulted in loss of an SfiI site in strains obtained from the newly infected ferrets. Thus, although minor differences in PFGE pattern were noted, H. mustelae lacks the genomic diversity observed in H. pylori.

Animals↗
PubMed1994

Glomerular charge selectivity in primary glomerulopathies.

1. Glomerular charge selectivity was assessed using the ratio of the clearance of pancreatic isoamylase to the clearance of the more anionic salivary isoamylase (CPAm/CSAm) in 53 patients with primary glomerulopathies (minimal change nephropathy, idiopathic membranous nephropathy, IgA nephropathy) and a wide range of albumin excretion rates and in 31 healthy subjects. Fractional clearances of pancreatic and salivary isoamylases (FCPAm, FCSAm) and of albumin (FCAlb) were also measured. 2. CPAm/CSAm and FCPAm were negatively correlated with FCAlb for the whole patient group (rs = -0.56 and rs = -0.65, respectively, P < 0.0001 for both), but there was no correlation of FCSAm with FCAlb. 3. For patients with near-normal albumin excretion rates (< 100 mg/24 h), there was no difference in CPAm/CSAm between the three types of glomerulopathy or between patients and healthy subjects. 4. These data suggest that glomerular charge selectivity at the size of amylase (which is smaller than albumin) is progressively lost as albuminuria increases from normal to the nephrotic range. Size restriction progressively increases until albuminuria is very heavy. When the albumin excretion rate is near normal, charge selectivity is also normal in the three main forms of primary glomerulopathy.

Adolescent↗
PubMed1994

High concentrations of vitamin A esters circulate primarily as retinyl stearate and are stored primarily as retinyl palmitate in ferret tissues.

OBJECTIVE AND METHODOLOGY: We determined the kinds and amounts of vitamin A compounds (retinol and various retinyl esters) circulating in serum and stored in liver and other selected tissues of ferrets, using high-performance liquid chromatography. RESULTS: The concentration of total retinyl esters in serum (43 +/- 1 mumol/L, mean +/- SEM) was 25 times greater than that of retinol (1.7 +/- 0.2 mumol/L). In serum, 56% of retinyl esters was retinyl stearate, 33% was retinyl palmitate, and 5% was retinyl oleate. In contrast, in liver, vitamin A was stored primarily as retinyl palmitate (51%); smaller amounts of retinyl oleate (19%) and retinyl stearate (16%) were found. In kidneys, adrenals, small intestine, adipose tissue, skin, stomach, and eyes, retinyl palmitate was also the predominant retinyl ester, followed by retinyl stearate. In colon, lungs, and bladder, equal amounts of retinyl palmitate and retinyl stearate were observed. Other retinyl esters present in smaller amounts in most of these tissues were retinyl oleate, retinyl linoleate and/or -myristate, retinyl heptadecanoate, retinyl arachidonate, and retinyl laurate. CONCLUSIONS: Thus, the primary form of vitamin A that circulates in the blood of ferrets is retinyl stearate, whereas the primary storage form of the vitamin in tissues is retinyl palmitate. Concentrations of total vitamin A in ferret serum and other tissues were 3-73 times greater than those reported for their corresponding human tissues.

Animals↗
PubMed1994

Phylogeny of Helicobacter isolates from bird and swine feces and description of Helicobacter pametensis sp. nov.

Previously, nine fecal isolates from wild birds and a domestic swine were identified as helicobacters by phenotypic characterization and reaction with a helicobacter genus-specific DNA probe. These isolates fell into three biotypes by analysis of phenotypic traits. To further characterize these isolates, full 16S rRNA sequences were determined for strains representing each biotype, and sequence comparison indicated that the strains represented three novel, phylogenetically defined Helicobacter species. Three 16S rRNA-based DNA probes were designed and used to identify the remaining strains. Probe reactivity divided the strains into the same three groups identified phenotypically. Six of the isolates represented a new species of the genus Helicobacter for which we propose the name Helicobacter pametensis sp. nov. The following phenotypic features distinguished H. pametensis from other Helicobacter and Campylobacter species: positive tests for oxidase, catalase, alkaline phosphatase, nitrate reduction, growth at 42 degrees C, and growth in the presence of 1% glycine; negative tests for urease, gamma glutamyl transpeptidase, indoxyl acetate hydrolysis, and hippurate hydrolysis; and susceptibility to nalidixic acid and cephalothin. H. pametensis cells were motile and possessed one subterminal sheathed flagellum at each end. The two additional Helicobacter species were similar to H. pametensis except that they were urease positive, hydrolyzed indoxyl acetate, and were resistant to cephalothin. Because these two additional species are phenotypically similar and are represented by only two isolates for one species and one isolate for the other, they are not formally named but are referred to as Helicobacter sp. "Bird-B" and Helicobacter sp. "Bird-C."(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Isolation of Helicobacter strains from wild bird and swine feces.

We report the first isolations of Helicobacter strains from wild birds and swine. Genus-specific oligonucleotide probes identified nine Cape Cod isolates from gull, tern, house sparrow, and pig feces as Helicobacter spp. and not Campylobacter spp. Antibiotic sensitivity and urease tests distinguished three phenotypes. Strains examined rapidly lost culturability under simulated natural conditions.

Animals↗