PubMed Health⌕ Search

Biomedical subjects

H F Stills

Publications and source records attributed to H F Stills.

At least 19 recordsLinked to original sources
PubMed2001

CD1d-reactive T-cell activation leads to amelioration of disease caused by diabetogenic encephalomyocarditis virus.

A subset of CD161 (NK1) T cells express an invariant Valpha14Jalpha281 TCR-alpha chain (Valpha(invt) T cells) and produce Th2 and Th1 cytokines rapidly in response to CD1d, but their physiological function(s) remain unclear. We have found that CD1d-reactive T cells mediate to resistance against the acute, cytopathic virus diabetogenic encephalomyocarditis virus (EMCV-D) in relatively Th1-biased, C57BL/6-based backgrounds. We show now that these results generalize to Th2-biased, hypersensitive BALB/c mice. CD1d-KO BALB/c mice were more susceptible to EMCV-D. Furthermore, alpha-galactosylceramide (alpha-GalCer), a CD1d-presented lipid antigen that specifically activates Valpha(invt) T cells, protected wild-type (WT) mice against EMCV-D-induced encephalitis, myocarditis, and diabetes. In contrast, neither CD1d-KO nor Jalpha281-KO mice were protected by alpha-GALCER: Finally, disease in Jalpha281-KO mice was comparable to WT, indicating for the first time equivalent roles for CD1d-reactive Valpha(invt) and noninvariant T cells in resistance to acute viral infection. A model for how CD1d-reactive T cells can initiate immune responses, which synthesizes current results, is presented.

Animals↗
PubMed2000

Improved model for teaching interventional EUS.

BACKGROUND: A swine model was previously developed for teaching endoscopic ultrasound (EUS). The purpose of this study was to improve this model and develop a method for creating focal lesions for EUS imaging and intervention. METHODS: Experiments were performed in farm pigs (Sus scrofa) under general anesthesia. Under real-time EUS guidance attempts were made to create a submucosal lesion and a focal mediastinal lesion, to perform EUS-guided fine-needle aspiration of the pancreas, and to confirm the site of injection during "sham" EUS-guided celiac block. RESULTS: A hypoechoic, submucosal mass was created in the stomach, which was then imaged by EUS and punctured trans-gastrically. Injection of saline solution in the mediastinum created a pseudo-mediastinal lymph node. A needle was then advanced trans-esophageally into the mediastinum to mimic EUS-guided fine-needle aspiration of a mediastinal lymph node. Abdominal exploration of the pigs after euthanasia confirmed injection of the sham celiac block around the celiac ganglion. CONCLUSION: The swine model is not only useful for teaching normal EUS anatomy, but it may be a useful model for teaching EUS-guided intervention.

Animals↗
PubMed1996

Evaluation of an agar gel immunodiffusion test kit for detection of antibodies to Mycobacterium paratuberculosis in sheep.

OBJECTIVE: To determine whether a commercially available agar gel immunodiffusion test approved for detecting antibodies to Mycobacterium paratuberculosis in cattle could be used for sheep. DESIGN: Experimental trial. SAMPLE POPULATION: Serum samples from 27 sheep confirmed to have paratuberculosis by means of acid-fast staining of smears of ileal mucosa, histologic examination of tissues, or bacteriologic culture; 7 sheep with clinical signs of paratuberculosis; and 55 sheep from 5 uninfected flocks. PROCEDURE: Serum samples were tested concurrently with the commercially available test and with a previously validated agar gel immunodiffusion test. Multiple samples collected from 13 infected sheep over a period of 6 years were also tested so that each test's ability to detect onset of seropositivity could be compared. RESULTS: For both tests, results for samples from all 55 uninfected sheep were negative, results for samples from 32 of the 34 sheep with paratuberculosis were positive, and results for the remaining 2 sheep with paratuberculosis were negative. Results of both tests were in agreement for 50 of 54 samples obtained from 13 infected sheep over time. The 4 samples for which results of the 2 tests disagreed were the fourth, eighth, and ninth of 10 samples from 1 sheep and the first of 6 samples from a second sheep. For all 4 samples, the commercially available assay yielded a weak-positive result, but the previously described test yielded a negative result. CLINICAL IMPLICATIONS: The commercially available agar gel immunodiffusion test approved for use in cattle may be useful in the differential diagnosis of paratuberculosis in sheep.

Animals↗
PubMed1995

Evaluation of an enzyme-linked immunosorbent assay licensed by the USDA for use in cattle for diagnosis of ovine paratuberculosis.

A commercially available Mycobacterium phlei-absorbed enzyme-linked immunosorbent assay (ELISA) approved to detect antibodies to Mycobacterium paratuberculosis in cattle was evaluated for its applicability in sheep. The potential for interference with ELISA results from cross-reacting antibodies to Corynebacterium pseudotuberculosis was also investigated. Serum samples were randomly selected from a collection of samples obtained in 1986-1991 from 6 infected and 5 noninfected sheep flocks varying in breed, age, and geographic origin. Tests were performed on sera from 27 paratuberculous sheep, confirmed by histopathology, bacteriologic culture, and/or acid-fast staining of ileal mucosal smears, and on sera from 246 noninfected sheep. The optical density of each sample was expressed as a percentage of the optical density of a known positive sheep serum sample tested on the same plate. These values were log-transformed to achieve normality of distribution, and sensitivity and specificity estimates were calculated based on 2 and 3 standard deviations above the mean of the percent positive value (PPV) of the noninfected sheep. A cutoff value of PPV > or = 55.74 resulted in an estimated sensitivity of 0.48 and a specificity of 0.95. Sera from 10 noninfected sheep with PPV above the cutoff level of 55.74% were absorbed with heat-treated C. pseudotuberculosis organisms in addition to M. phlei antigens. Sera from 14 ELISA-positive paratuberculous sheep and 23 ELISA-negative noninfected sheep were similarly treated, and results were compared. Absorption with C. pseudotuberculosis resulted in a significant decrease in PPV in all 3 groups of sheep sera, but a greater decrease was observed in the noninfected sheep with PPV above the cutoff level when compared with noninfected sheep with PPV below that level. Results of this study suggest that ELISA may be of value in screening sheep flocks for paratuberculosis, but further experimentation is needed to optimize the sensitivity and specificity of the assay. Exposure to C. pseudotuberculosis may confound results obtained by M. phlei-absorbed ELISA for paratuberculosis.

Animals↗
PubMed1994

Detection of flagellar antigen of Campylobacter jejuni and Campylobacter coli in canine faeces with an enzyme-linked immunosorbent assay (ELISA)--new prospects for diagnosis.

A new diagnostic procedure was developed to detect the flagellar antigen of Campylobacter jejuni and Campylobacter coli in canine faecal specimens and was tested on faecal samples from random-source dogs obtained from the local dog pound. Extraction of acid-soluble proteins was performed on faecal specimens and the extracted material was evaluated using species-specific monoclonal antibodies in an enzyme-linked immunosorbent assay. The assay detected all C. jejuni or C. coli infected specimens compared with direct selective faecal culture. One of 18 faecal specimens culture-negative for C. jejuni was identified as positive by the assay, i.e. a false positive rate of 1 of 18 (5.6%) and a corresponding specificity of 94.4%. These results suggest that the screening procedure developed to detect flagellar antigens of C. jejuni and C. coli in canine faecal samples should be further investigated as a diagnostic alternative to culture.

Animals↗
PubMed1994

Comparative analysis of the 16S rRNA gene sequence of the putative agent of proliferative ileitis of hamsters.

Proliferative ileitis of hamsters is consistently associated with the presence of intracellular bacteria in affected ileal epithelial cells. The 16S rRNA gene sequence of the putative etiologic agent of proliferative ileitis was determined by using cell culture-maintained organisms. The highest level of relatedness (98.4%) was observed with a newly described obligately intracellular bacterium obtained from porcine intestines, and the level of homology with Desulfovibrio desulfuricans was 87.5%.

Animals↗
PubMed1993

Evaluation of the skeletal effects of combined mild dietary calcium restriction and ovariectomy in Sinclair S-1 minipigs: a pilot study.

A pilot study was conducted to investigate the combined effects of ovariectomy (OVX) with preceding and concomitant mild dietary calcium restriction on the minipig skeleton. Minipigs 4 months old were fed diets containing 0.9, 0.75, or 0.5% calcium (Ca). At 10 months, the 0.75 and 0.5% pigs were OVX and the 0.9% were either sham operated or OVX. All pigs were maintained on their respective diets for an additional 6 months. Excised lumbar vertebrae and long bones were evaluated by densitometry and histomorphometry, and vertebral cancellous bone samples were tested biomechanically. In pigs fed the 0.9% Ca diet, OVX alone effected decreases of 6% in vertebral bone mineral density (BMD), 15% in trabecular bone volume (BV/TV), and 13% in trabecular number (Tb.N), an increase of 15% in trabecular separation (Tb.Sp), and a nonsignificant increase (p < 0.056) in vertebral cancellous final erosion depth (F.E.De) compared with the 0.9% Ca sham-operated group. Decreasing dietary Ca to 0.5% in combination with OVX effected an 8% reduction in vertebral BMD that was not associated with any significant alterations in parameters of vertebral cancellous bone microstructure or remodeling compared with the 0.9% Ca sham-operated pigs. Increases in serum PTH noted in the 0.5% Ca OVX group were generally paralleled by increases in calcitriol. In OVX pigs fed a diet containing 0.75% Ca, a 10% reduction in vertebral BMD was observed. This was associated with significant increases in F.E.De and vertebral marrow star volume (Ma.St.V) compared with the 0.9% Ca sham-operated pigs and the other OVX groups. In addition, Tb.Sp was increased and Tb.N decreased compared with the 0.9% Ca sham-operated pigs. Increases in serum PTH in this group were not accompanied by increases in calcitriol. Midradial and midfemoral BMD values were reduced in the 0.75 and 0.5% Ca OVX groups compared with the 0.9% Ca sham-operated pigs. Histomorphometric analyses of cortical bone suggested the reduction in cortical bone mass in the 0.75% Ca OVX group may have been largely due to net loss on the endocortical surface versus possible failure to accrue bone in the 0.5% Ca OVX group. Ash density and biomechanical parameters for vertebral cancellous bone decreased progressively in the 0.9% sham-operated, 0.9% Ca OVX, and 0.75% Ca OVX groups and then increased in the 0.5% Ca OVX group. After normalization for bone mass (ash), mechanical changes were still apparent, particularly for the 0.75% Ca OVX group compared with other OVX groups, reflecting that structural changes had taken place in the trabecular network.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid Phosphatase↗
PubMed1993

Comparison of the major outer-membrane protein (MOMP) gene of mouse pneumonitis (MoPn) and hamster SFPD strains of Chlamydia trachomatis with other Chlamydia strains.

Restriction fragments containing the major outer-membrane protein (MOMP) gene from two nonhuman (rodent) strains of Chlamydia trachomatis, the mouse pneumonitis (MoPn) strain and the SFPD strain isolated from hamsters with transmissible proliferative ileitis, were cloned and sequenced. The MOMP genes of both MoPn and SFPD encode an identical 22-amino acid leader peptide and mature polypeptides of 365 and 382 amino acids, respectively. Alignment of the MOMP genes of the two rodent strains revealed 91% identity. By comparison with other known chlamydial MOMP gene sequences, there was 80%-83% identity with human biovars strains of C. trachomatis, and there was 69%-70% identity with C. psittaci and C. pneumoniae strains. The main differences in these sequences were clustered into four variable domains. A minimum-length evolutionary tree was constructed on the basis of the MOMP gene variable positions by using PIMA package software. The minimum mutation distances indicated that (i) the MOMP genes of all chlamydial strains may have evolved from a common ancestor; (ii) all the strains of C. trachomatis compose one of the subtrees, and strains of C. psittaci and C. pneumoniae compose the other subtree; and (iii) in the C. trachomatis subtree, the human and the rodent strains are divided into two clusters. The branching pattern of this evolutionary tree is generally consistent with current classification based on serological, morphological, and other biological characteristics.

Amino Acid Sequence↗
PubMed1993

Antigenic specificity and morphologic characteristics of Chlamydia trachomatis, strain SFPD, isolated from hamsters with proliferative ileitis.

Profound diarrhea associated with proliferating intestinal cells containing intraepithelial campylobacter-like organisms (ICLO) occurs in a variety of mammalian hosts, particularly swine and hamsters. Recently, intracellular bacteria were isolated from proliferative intestinal tissue of hamsters and propagated in intestine cell line 407. Oral inoculation of hamsters with cell culture lysates containing these organisms reproduced the disease in susceptible hamsters. In the present study, an intracellular bacterium from the INT 407 cell line was shown by a variety of techniques to be a member of the genus Chlamydia and has been designated Chlamydia sp. strain SFPD. McCoy cells infected with Chlamydia sp. strain SFPD demonstrated bright fluorescent-stained intracytoplasmic inclusions when examined with fluorescein-labeled species-specific C. trachomatis monoclonal antibodies. The organism also reacted to fluorescein-labeled polyclonal but not monoclonal ICLO "omega" antisera. Ultrastructural examination of the Chlamydia sp. strain SFPD from McCoy cells revealed electrondense elementary bodies and a less electron-dense reticulate-like body that was circular; both features are consistent in morphology to developmental forms of Chlamydia and do not conform to ICLO morphology. Molecular studies, 16S ribosomal sequence analysis, and sequencing of the outer membrane protein confirmed that the isolate is a C. trachomatis closely related to the mouse pneumonitis strain of C. trachomatis.

Animals↗
PubMed1991

Isolation of an intracellular bacterium from hamsters (Mesocricetus auratus) with proliferative ileitis and reproduction of the disease with a pure culture.

An intracellular bacterium was isolated from hamsters (Mesocricetus auratus) with proliferative ileitis. The organism was isolated in Intestine 407 and GPC-16 cell cultures (incubated in a microaerophilic atmosphere) from isolated and lysed epithelial cells from hamsters with proliferative ileitis. The bacterium measured 1.4 to 1.7 microns in length by 0.26 to 0.34 microns in width, was slightly curved, and had an irregular trilaminar cell wall. Inoculation of hamsters with a cell culture lysate containing the organism or a 0.65-microns-pore-size filtrate of an infected-cell lysate resulted in the typical lesions of proliferative ileitis in approximately 50% of the animals in 28 days. Hamsters inoculated with uninfected cells or a 0.2-microns-pore-size filtrate of an infected-cell lysate remained uninfected. Attempts to propagate the organism on cell-free media have been unsuccessful.

Animals↗
PubMed1990

Efficacies of erythromycin and chloramphenicol in extinguishing fecal shedding of Campylobacter jejuni in dogs.

Oral treatment regimens of erythromycin stearate and chloramphenicol were evaluated in naturally infected laboratory colony dogs for their efficacies in extinguishing fecal shedding of Campylobacter jejuni. Of the 25 Campylobacter-infected English Foxhounds in the study, 9 were assigned to erythromycin treatment, 9 to chloramphenicol treatment, and 7 to no treatment. Antimicrobials were administered for 12 days. All of the dogs that received erythromycin stearate ceased shedding C jejuni by the fourth day of treatment and remained negative throughout the treatment period. Chloramphenicol was associated with a reduction in shedding from 100% to 57% by the ninth day of treatment. Within 9 days of the discontinuation of antimicrobial treatment, C jejuni was isolated from all chloramphenicol-treated dogs and 89% erythromycin-treated dogs.

Animals↗
PubMed1989

Experimental production of proliferative ileitis in Syrian hamsters (Mesocricetus auratus) by using an ileal homogenate free of Campylobacter jejuni.

The role of Campylobacter jejuni in the pathogenesis of proliferative ileitis of Syrian hamsters (Mesocricetus auratus) has been uncertain. C. jejuni has been implicated as the etiologic agent on the basis of the campylobacter-type morphology of the intracellular organism and the repeated microbiologic isolation of C. jejuni from hamsters with proliferative ileitis. The inability to reproduce the disease with pure culture inocula, coupled with immunohistochemical studies, however, has suggested that although C. jejuni may be present in the ilea of infected hamsters, its involvement in the pathogenesis of proliferative ileitis is questionable. In this study hamsters were inoculated with infective ileal homogenates prepared from ilea which were extensively washed to remove the ileal contents before grinding. The ilea from hamsters inoculated with this homogenate were also washed before being ground and used to experimentally inoculate a second group of hamsters. Of the 20 hamsters from this second group, 12 developed lesions typical of proliferative ileitis. Extensive microbiologic cultures from these hamsters were negative for C. jejuni. Immunofluorescence studies with a C. jejuni-specific monoclonal antibody were also negative. The use of a Campylobacter genus-specific monoclonal antibody, however, revealed numerous campylobacter-type organisms within the ileal epithelial cells of the crypts and villi. The presence of C. jejuni is therefore apparently not necessary for the production of proliferative ileitis in hamsters, and the intracellular campylobacter-type organism present in the ileal epithelial cells of infected hamsters is probably not C. jejuni.

Animals↗
PubMed1989

Isolation of a Campylobacter-like organism from healthy Syrian hamsters (Mesocricetus auratus).

A Campylobacter-like organism was isolated from the ilea of normal hamsters. The organism was isolated from an ileal homogenate which was passed through a filter (0.65-micron pore size) and cultured on blood-agar plates in a microaerophilic atmosphere at 37 degrees C. Pinpoint translucent colonies were first observed after 120 h of incubation. The isolated organism measured 2.0 to 3.5 microns in length (excluding flagella) by 0.17 to 0.25 micron in width and typically had a single terminal sheathed flagellum. The organism was oxidase, catalase, and urease positive, reduced nitrates, and was susceptible to nalidixic acid (30-micrograms disk) and resistant to cephalothin (30-micrograms disk). Unlike Campylobacter pylori subsp. mustelae, this organism did not hydrolyze indoxylacetate. Immunofluorescence studies with a Campylobacter species-specific monoclonal antibody (8322-2E6) revealed the presence of numerous positively stained organisms within the crypt epithelial cells of the hamsters from which this organism was isolated. The role of this organism in the pathogenesis of proliferative ileitis in hamsters is uncertain, as is the taxonomic relationship of this organism to other members of the genus Campylobacter.

Animals↗
PubMed1989

Effects of sample holding time, temperature, and atmosphere on the isolation of Campylobacter jejuni from dogs.

Stool specimens were collected from 39 dogs, inoculated onto Campylobacter blood agar plates, and divided into four subsamples. Subsamples were held at 4 and 25 degrees C in room air and in a microaerobic environment and were reinoculated at 1, 2, 3, 4, 6, and 8 h. C. jejuni survived at least 3 h when it was held at 4 degrees C, but less than 2 h when it was held at 25 degrees C. The holding atmosphere was not associated with a difference in isolation rates.

Aerobiosis↗
PubMed1988

Comparison of broth enrichment and direct plating for the isolation of Campylobacter jejuni from dogs.

Two techniques for the isolation of Campylobacter jejuni from feces, direct plating and thioglycolate broth enrichment, were compared. A total of 272 rectal swab cultures were performed on 156 laboratory dogs. Campylobacter blood agar plates and Campylobacter thioglycolate broth were inoculated immediately upon sampling of the dogs. After incubation at 4 degrees C for 12 to 16 h, material from the Campylobacter thioglycolate medium was inoculated onto Campylobacter blood agar plates. A total of 157 samples were positive for C. jejuni; 154 were positive by the direct method and 112 were positive by the enrichment technique. Forty-five samples which were negative by the enrichment were positive by the direct method, and three samples which were negative by the direct method were positive for C. jejuni by the enrichment method. The use of the enrichment step resulted in an increase in the isolation rate from 56.6 to 57.7%.

Animals↗
PubMed1987

Utilization of monoclonal antibodies to evaluate the involvement of Campylobacter jejuni in proliferative ileitis in Syrian hamsters (Mesocricetis auratus).

The role of Campylobacter jejuni in the pathogenesis of proliferative ileitis in Syrian hamsters was evaluated with monoclonal antibodies of different specificities. Monoclonal antibodies were produced with two different specificities: one for all members of the genus Campylobacter tested (antibody 8322-2E6) and one for C. jejuni and Campylobacter coli (antibodies 841-2A11, 841-4C6, and 841-5B1). Heal sections from healthy hamsters, from hamsters with naturally occurring proliferative ileitis, and from hamsters with experimentally induced proliferative ileitis were examined by using fluorescein isothiocyanate-labeled, Campylobacter sp.-specific 8322-2E6 and tetramethylrhodamine isothiocyanate-labeled C. jejuni-C. coli-specific 841-2A11 for direct dual-labeling immunofluorescence. Organisms which stained with the C. jejuni-C. coli-specific monoclonal antibody were observed in the ileal lumens and along the distal tips of the villi of hamsters with either experimentally induced or naturally occurring proliferative ileitis. In contrast, organisms identified by the Campylobacter sp.-specific monoclonal antibody were present deep within the villus lumens and crypts and intracellularly within the apical portions of the epithelial cells. No organisms stained with the C. jejuni-C. coli-specific monoclonal antibody were observed in ileal sections from control hamsters; an occasional intracellular organism stained with the Campylobacter sp.-specific monoclonal antibody was observed in 2 of 10 control hamsters. Thus, at least two immunologically distinct patterns were identified in ileal sections from hamsters with proliferative ileitis. On the basis of these results, we conclude that the organism seen intracellularly in ileal sections from hamsters with proliferative ileitis is a member of the genus Campylobacter but that it probably is not C. jejuni or C. coli.

Animals↗
PubMed1986

Malignant lymphoma in a Sinclair miniature pig.

Malignant lymphoma was diagnosed in a 3-year-old, male Sinclair(S-1) miniature pig with acute anorexia, depression, fever, and markedly enlarged inguinal lymph nodes. Results of an initial hemogram indicated a leukocyte count of 121,489 cells/mm3. Most of the leukocytes were mononuclear cells of various sizes, nuclear chromatin pattern, number of nucleoli, amount of cytoplasm, and amount of staining. Cytochemical staining and flow cytometric evaluation of the leukocytes indicated a large number of hypodiploid lymphoblasts in the peripheral blood. Gross necropsy findings included enlargement of all lymph nodes, a pale liver, and multifocal pale areas scattered throughout the kidneys. Microscopic examination indicated massive infiltration of abnormal lymphoid cells into most major organs and complete loss of normal morphologic features of all lymph nodes.

Animals↗