PubMed Health⌕ Search

Biomedical subjects

R Ashman

Publications and source records attributed to R Ashman.

11 recordsLinked to original sources
PubMed2005

Enhanced clearance of Candida albicans from the oral cavities of mice following oral administration of Lactobacillus acidophilus.

Orally administered live Lactobacillus acidophilus was assessed for its capacity to enhance clearance from the oral cavity of DBA/2 mice shown previously to be 'infection prone'. L. acidophilus fed to DBA/2 mice significantly shortened the duration of colonization of the oral cavity compared to controls. Enhanced clearance of Candida albicans correlated with both early mRNA gene expression for interleukin (IL)-4 and interferon (IFN)-gamma and expression of their secreted products in cultures of cervical lymph nodes stimulated with Candida antigen. In addition rapid clearance correlated with higher levels of IFN-gamma and nitric oxide in saliva. Delayed clearance, less pronounced levels of the cytokine response, saliva IFN-gamma and nitric oxide, and later mRNA expression for IL-4 and IFN-gamma relative to feeding with the L. acidophilus isolate were noted in mice fed a different Lactobacillus isolate (L. fermentum). These observations indicate significant variations in individual isolates to activate the common mucosal system.

Administration, Oral↗
PubMed1994

Induction of ornithine decarboxylase activity in mouse B lymphocytes.

We have examined the role in B cell activation of ornithine decarboxylase (ODC), the labile rate-limiting enzyme in the synthesis of polyamines thought to be required for S phase entry in all cells. When small resting mouse splenic B cells were stimulated with the mitogenic agents phorbol myristate acetate (PMA) plus ionomycin (lo), LPS or the B cell specific agent F(ab')2 anti-lg, ODC activity was greatly increased. ODC activity in small dense B cells remained near baseline levels for the first 6 h after treatment with LPS, but then increased approximately 150-fold in the next 18 h. When purified B cells were not separated by cell density, ODC activity was 30-fold greater at baseline and rose earlier after LPS stimulation, reaching a level about three times that of LPS-stimulated small, dense B cells at 24 h, implying that large (preactivated) B cells have much greater ODC responses than small, dense B cells. ODC activity, like S phase entry, could also be induced in small, dense B cells by PMA and lo but failed to respond to either agent alone. ODC levels rose transiently by approximately 40-fold between 2 and 6 h following stimulation of small B cells with F(ab')2 anti-lg, then declined to baseline. Whole anti-lg did not stimulate ODC activity and also blocked the F(ab')2 anti-lg mediated increase in ODC activity, just as it produced the expected inhibition of thymidine incorporation and cellular progression into S phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Posterior plating of the cervical spine. A biomechanical comparison of different posterior fusion techniques.

Posterior arthrodesis is a preferred treatment for posttraumatic instability of the cervical spine. While most surgical constructs yield predictably high rates of fusion in satisfactory alignment, certain injury patterns involving fractures of the lamina or spinous processes may preclude rigid immobilization by simple wiring techniques. Plate fixation of the posterolateral masses has been advocated for such injuries. The purpose of this biomechanical study was to test the relative stiffness provided by different posterior fusion constructs, including lateral mass plating. All testing was performed on fresh, unembalmed cadaveric spines divided into two vertebral segment units. Muscular tissue was stripped from the specimens, but all discal and ligamentous structures were preserved. Four different posterior fixation constructs were tested. These included 1) Rogers interspinous wiring, 2) Halifax laminar clamps, 3) bilateral 1/3 tubular plates on the lateral masses, using unicortical screws, and 4) bilateral 1/3 tubular plates on the lateral masses, using bicortical screws. Stiffness measurements were taken in both flexion and extension on all specimens. Yield strength and fatigue strength of the spines were not measured. It was found that 1/3 tubular plates secured with bicortical screws to the lateral masses provided the highest mean stiffness. Less stiffness was found in spines stabilized by Halifax clamps, interspinous wiring, and plates secured with unicortical screws. There was, however, no statistically significant difference in stiffness provided by any of these four implants. It was concluded that there is no advantage in plate fixation over standard fusion constructs in augmenting the stiffness of posterior fixation of the cervical spine.

Biomechanical Phenomena↗
PubMed1988

Introduction of a porcine growth hormone fusion gene into transgenic pigs promotes growth.

Six transgenic pigs have been produced by microinjecting a human metallothionein promoter/porcine growth hormone gene construct into the pronuclei of fertilized eggs which were transferred to synchronized recipient sows. The resulting transgenic animals contained between 0.5 and 15 copies of the gene construct per cell, and at least one of the animals expressed the introduced gene and grew at an increased rate compared to both transgenic and non-transgenic littermates. Some of the transgenic animals that did not appear to grow at increased rates were found to contain rearranged gene sequences. Two of the transgenic pigs have been shown to pass on the introduced genes to their offspring.

Animals↗
PubMed1981

Ir gene function in an I-A subregion mutant B6.C-H-2bm12.

The B6.C-H2bm12 (bm 12) strain has a mutation in the I-A subregion of the murine H-2 complex and is characterized by a loss of serologically detected Ia antigens and a strong graft rejection and mixed lymphocyte response between parent and mutant. It was presumed that the mutation affected the Ia-1 gene and to determine the relationship of Ia antigens and Ir genes, the immune responses of mutant and parent were compared. The immune responses to poly(L-Tyr,LGlu)-poly(DLAla)--poly(LLys), poly(Phe,Glu)-poly(DLAla)--poly(LLys), and poly(His,Glu)-poly(DLAla)--poly(LLys) in parent and mutant were same, indicating the Ia-1 and the Ir genes for these antigens are not identical. By contrast, although C57BL/6 gave a good response, the mutant strain was unable to generate cytotoxic T lymphocytes to the male-specific H-Y antigen--a response under I-A subregion Ir gene control, which now must be considered to be the Ia-1 gene. In addition, complementary Ir genes in the H-2b haplotype for the H-Y immune response could be detected when the bm12 mutant was used.

Animals↗
PubMed1980

Enhancement of murine erythroid colony formation in the presence of activated T lymphocytes.

Erythroid colony formation was enhanced by treatment of mouse bone marrow cells with PHA prior to culture in diffusion chambers implanted into intact mice. Addition of PHA-pretreated thymocytes, lymph node lymphocytes, and spleen cells to untreated bone marrow cells also resulted in increased numbers of erythroid colonies in diffusion chambers but had no effect on myeloid colonies. PHA did not augment erythroid colony formation when bone marrow was depleted of Thy 1-bearing cells, although cells capable of erythroid differentiation were still present as judged by the response to erythropoietin. Furthermore, mixing of bone marrow depleted of Thy 1 + cells with PHA-treated thymocytes restored augmented erythroid colony formation. Lack of responsiveness of bone marrow cells to concanavalin A and pokeweed mitogen may indicate that a specific T cell subpopulation reacting with PHA is able to stimulate erythropoiesis. Note that addition of untreated thymocytes, lymph node lymphocytes, and spleen cells into cultures had no effect.

Animals↗
PubMed1976

Anaerobic (putrid) lung abscess in adolescence.

Two adolescents with acute anaerobic (putrid) lung abscess were seen during an influenza epidemic. One patient, who had a history of seizures and a dental infection, had a classic predisposition to this disease. In the second patient, the abscess was apparently acquired as a complication of influenza. In both cases, the preliminary diagnosis was staphylococcal pneumonia with pneumatocele. It is suggested that failure to consider an anaerobic cause in pulmonary infections, inappropriate specimens, transport and culture of anaerobic material, and the sensitivity of oral cavity-derived anaerobes to penicillin, serve to mask the true frequency of anaerobic lung infections in childhood and adolescence.

Adolescent↗