Biomedical subjects

H L Leary

Publications and source records attributed to H L Leary.

9 recordsLinked to original sources

PubMed2000

A bacterial high-affinity GABA binding protein: isolation and characterization.

A gamma-aminobutyric acid (GABA) binding protein (GBP) was isolated from a bacterial mutant which has high-affinity GABA binding characteristics comparable with the GABA(A) brain receptor in mammals. The GBP was partially purified and characterized and was shown to be a periplasmic protein of approximately 42,000 molecular weight. To determine the molecular weight, a bacterial GABA binding assay was used with SDS-PAGE. This procedure did not require large amounts or complete purification of protein and may be useful as a simple method in estimating the molecular weight of other bacterial binding proteins.

Animals↗

PubMed1995

Oral transforming growth factor-alpha enhances jejunal mucosal recovery and electrical resistance in piglet rotavirus enteritis.

A randomized, investigator-masked trial determined the effects of oral recombinant human transforming growth factor-alpha (TGF alpha) on jejunal mucosal recovery in 75 piglets with rotavirus diarrhea. Rotavirus inoculation of artificially reared piglets induced subtotal (approximately 50%) villus atrophy and watery diarrhea. Dietary TGF alpha was associated with significant restoration of villus surface area by 4 d postinoculation (p.i.) and complete restoration by 8 d p.i., whereas saline-treated animals required 12 d for recovery. Jejunal segments from clinically recovered TGF alpha-treated piglets showed an increase in electrical resistance across the epithelial barrier in vitro which was proportional to villus height. TGF alpha treatment for 12 d also produced a 30-50% increase in jejunal mucosal mass (protein content and wet weight), compared with the corresponding values in saline-treated piglets and in uninfected controls. However, oral TGF alpha did not hasten the resolution of diarrhea, enhance the specific activities of jejunal mucosal digestive enzymes, or increase jejunal glucose-stimulated Na+ absorption in vitro. We conclude that dietary TGF alpha stimulates jejunal mucosal hypertrophy, improves barrier function, and enhances regrowth of villi in rotavirus enteritis; however, it does not facilitate the restoration of functional activity or mucosal digestive enzymes. Oral TGF alpha can facilitate intestinal epithelial recovery in diseases associated with mucosal damage.

Administration, Oral↗

PubMed1994

Bovine antibody against Cryptosporidium parvum elicits a circumsporozoite precipitate-like reaction and has immunotherapeutic effect against persistent cryptosporidiosis in SCID mice.

Control of cryptosporidiosis is currently hampered by the absence of drugs or vaccines proven consistently effective against Cryptosporidium parvum. On the basis of observations that anti-C. parvum antibody has therapeutic effect against cryptosporidiosis, cows were immunized with C. parvum to produce hyperimmune colostral antibody. An antibody-rich fraction was prepared and differentiated from control (nonhyperimmune) antibody by enzyme-linked immunosorbent assay, immunofluorescence assay, immunoelectron microscopy, and in vitro neutralizing titer against DEAE-cellulose-isolated C. parvum sporozoites. Oocyst, purified sporozoite, and merozoite antigens recognized by hyperimmune antibody were defined by Western blot (immunoblot). Hyperimmune antibody recognized antigens common to oocysts, sporozoites, and merozoites, as well as stage-specific antigens. Upon incubation with hyperimmune antibody, sporozoites underwent distinct morphologic changes characterized by progressive formation and eventual release of membranous sporozoite surface antigen-antibody complexes, similar to the malaria circumsporozoite precipitate reaction. The infectivity of sporozoites having undergone this reaction was neutralized. The reaction was minimal or absent on sporozoites incubated with control antibody. To determine therapeutic effect in vivo, persistent C. parvum infection was established in adult severe combined immune-deficient (SCID) mice by oral inoculation with 10(7) oocysts. At 5 weeks postinfection, infected mice were treated for 10 days with hyperimmune or control antibody by inclusion in drinking water and daily gavage. Fecal oocyst shedding and infection scores in the gastrointestinal tract and gall bladder/common bile duct in hyperimmune antibody-treated mice were significantly lower than those in the control antibody-treated mice. Hyperimmune bovine antibody prepared against C. parvum may provide a first-generation therapy for control of cryptosporidiosis. Additionally, the defined antigens can be evaluated as subunit immunogens to produce better-characterized polyclonal antibody for control of cryptosporidiosis or as targets for monoclonal antibody-based immunotherapy.

Animals↗

PubMed1992

Nonclinical testing of formulas containing hydrolyzed milk protein.

The allergenic potential of cow milk-based infant formula can be reduced by protein hydrolysis. Controlled clinical studies are necessary to demonstrate conclusively the biologic efficacy of these formulations in human beings. Nonclinical testing programs provide manufacturers with the opportunity to characterize various molecular and immunologic properties of these hydrolysates and their corresponding final product forms. Physicochemical analyses provide data relating to the extent of protein hydrolysis and peptide molecular weight distribution. Immunochemical analyses can semiquantitatively estimate hydrolysate reactivity with preformed antibody. The ability of hydrolysate-based products to induce an immune response can be evaluated by using animal models. It is the responsibility of the manufacturer to choose the appropriate combination of nonclinical tests and use them to document product consistency, thus helping to ensure consistent clinical performance.

Animals↗

PubMed1991

Protection of agammaglobulinemic piglets from porcine rotavirus infection by antibody against simian rotavirus SA-11.

Rotavirus, a double-stranded RNA virus, has been implicated as a diarrhea-provoking agent in a variety of animal species. Several previous reports have shown that immunization with a single serotype may result in increased in vitro neutralization titers against serotypes not represented in the immunogen. This study was undertaken to determine whether antibody from cows immunized against simian rotavirus strain SA-11 (which is alien to pigs) could protect neonatal piglets from infection with a North Carolina isolate of porcine rotavirus. Accordingly, cows were immunized with SA-11 and an immunoglobulin G (IgG)-rich fraction was isolated from their colostrum. An IgG-rich fraction was similarly isolated from colostrum of nonimmunized cows. At equal concentrations, IgG from SA-11-immunized cows had two- to fourfold higher neutralization titers to seven of eight test strains of rotavirus, including SA-11 (serotype 3); human rotavirus serotypes 1, 3, and 4; North Carolina porcine rotavirus (serotype undetermined); Ohio State porcine rotavirus (serotype 5); and bovine rotavirus (serotype 6). The IgG-rich fractions were fed as dietary supplements to agammaglobulinemic piglets infected with the North Carolina porcine rotavirus. IgG from the SA-11-immunized cows was about eightfold more effective in protecting piglets than was IgG from nonimmunized cows.

Agammaglobulinemia↗

PubMed1984

An assay to measure antigen-specific immune complexes in food-allergy patients.

An allergen- and isotype-specific assay to quantify the presence of serum immune complexes is described. This assay is based on a two-site recognition system so that only molecular complexes containing both antigen and antibody are counted. In this study affinity-purified antibodies to egg and milk whey were used on paper discs in conjunction with a soluble, labeled anti-immunoglobulin (IgE or IgG specific). To evaluate the assay, immune complexes were prepared in vitro by mixing antigen at different concentrations with serum from a patient with high levels of antibody. Complexes were detectable over a 5 log range of antigen concentration. The lower limit of sensitivity of the assay was estimated to be 5.8 ng of complexed IgE per milliliter of patient serum. To determine if the assay could detect natural in vivo-formed complexes, sera from patients with positive RAST scores to egg white or milk were selected for a preliminary study. Three of the nine egg white-positive sera and two of the nine milk-positive sera were found to contain significant levels of IgE immune complexes. The versatility and sensitivity of the assay should now make it feasible to design experiments to elucidate the role, if any, of circulating immune complexes in the etiology of food allergy.

Antibodies, Anti-Idiotypic↗

PubMed1982

Immunohistochemical localization of IgG1 and IgG2 in prepartum and lactating bovine mammary tissue.

The differential distributions of IgG1 and IgG2 were determined in prepartum and lactating bovine mammary tissue by indirect immunofluorescence. IgG1 was found predominately within the alveolar epithelial cells and lumens of prepartum tissue whereas IgG2 was largely confined to the stromal area surrounding the alveoli. Both IgG subclasses were confined predominately to the stroma in lactating tissue. Few IgG containing stromal cells were readily distinguished in any of the mammary tissue used in this study.

Animals↗

PubMed1979

The preferential transport of immunoglobulin G by the small intestine of the neonatal piglet.

Previous work dealing with the acquisition of passive immunity by the neonatal mammal has shown that the piglet is qualitatively nonselective with regard to the transport of macromolecules from the gut to the blood, whereas rats, mice and hamsters transport only immunoglobulin G (IgG) in detectable quantities. The ability of enterocytes of the proximal and distal small intestine of piglets to internalize fluorescent porcine IgG, bovine albumin or a mixture of these two fluorescent proteins was assessed. At the light microscopic level (macropinocytosis) porcine IgG and bovine albumin were internalized with equal facility by these enterocytes. To determine whether piglets preferentially transported porcine IgG versus bovine albumin, other piglets were gavaged with these proteins or these proteins were injected into ligated segments of the proximal or distal small intestine. Enterocytes in the proximal part of the small intestine transported more of these proteins (P less than 0.10) than did those in the distal part. When either bovine albumin or porcine IgG was presented separately to the piglet's gut, both were transported to about the same low level. However, when mixtures of these proteins were presented, IgG was preferentially transported, i.e., albumin enhanced IgG transport. Porcine albumin or polyvinylpyrrolidone (PVP) also enhanced porcine IgG transport. It was proposed that the preferential transport of IgG occurred by a micropinocytotic mechanism (not visible by light microscopy) and that other macromolecules such as albumin and PVP enhanced IgG transport by nonspecifically stimulating micropinocytosis.

Animals↗

PubMed1978

Effect of feeding on the cessation of transport of macromolecules by enterocytes of neonatal piglet intestine.

To elucidate further the role of digesta in the cessation of transport of macromolecules to the blood by enterocytes of neonatal piglet small intestine, a portion of the ileum was surgically isolated and vented to the exterior. The ability of this isolated intestine to transport macromolecules was compared with that of the intestine remaining in the digestive pathway in the same piglet. The isolated intestine ceased transporting macromolecules at the same time as the intestine in the digestive pathway, thus implicating a humoral signal that is responsible for the cessation of transport.

Albumins↗