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Biomedical subjects

M A Barry

Publications and source records attributed to M A Barry.

At least 37 records · Page 2Linked to original sources
PubMed1998

A foodborne outbreak of Cyclospora cayetanensis at a wedding: clinical features and risk factors for illness.

BACKGROUND: Cyclospora cayetanensis, a coccidian parasite, has increasingly been recognized as a cause of gastrointestinal tract illness. We describe an outbreak of Cyclospora infection following a wedding reception. OBJECTIVES: To investigate and characterize risk factors associated with the outbreak of Cyclospora and to describe the observed clinical course and spectrum of illness. METHODS: Retrospective cohort study involving 94 of the 101 guests who attended a wedding reception at a restaurant in Boston, Mass. RESULTS: Fifty-seven respondents met the case definition of infection; 12 of these had laboratory-confirmed Cyclospora. The epidemic curve was consistent with a point source outbreak with a median incubation period of 7 days. Commonly reported symptoms included diarrhea (100%), weight loss (93%), fatigue (91%), and anorexia (90%). The illness had a characteristic waxing and waning course, with 51 persons (89%) reporting recurring symptoms and 35 (61%) reporting illness lasting more than 3 weeks. By univariate analysis, infection was significantly associated (P<.05) with consumption of wine and a dessert containing raspberries, strawberries, blackberries, and blueberries. Only the dessert remained significant by stratified analysis with an adjusted relative risk of 2.1 (95% confidence interval, 1.4-3.2). CONCLUSIONS: Findings from this study support a point source outbreak of the newly identified pathogen C cayetanensis, with berries as the vehicle of transmission. It suggests that Cyclospora may cause severe diarrhea associated with profound anorexia and weight loss, and should be considered in the evaluation of prolonged gastrointestinal tract illness.

Animals↗
PubMed1997

Biological features of genetic immunization.

Genetic immunization (a.k.a. DNA-based immunization) shows promise at least as a convenient method to test and discover new vaccines and may be an efficient vaccine delivery system. However, relatively little is known about the parameters affecting its effectiveness, let alone its basic underlying biological mechanisms. Here we report on investigations of some of the factors that determine the quantity and quality of the immune response with genetic immunization. We find that for non-toxic proteins the antibody response correlates well with the level of expression as does the cellular response to a certain level. The augmentation of the immune response by co-introduction of a cytokine gene as a genetic adjuvant is also responsive to the expression level of the antigen. The immune response is inversely correlated to the age of the mice and at least part of this effect is through level of expression of the antigen. Gene gun administration of the transgene to the skin has the advantage over muscle injection in that ca 100-fold less DNA is required for the same level of expression and the injections are more reproducible in effect. Finally, the apparent differences in Th2 (gun) vs Th1 (muscle) responses between the two modes can at least partly be accounted for by differences in the amount of plasmid DNA typically administered.

Aging↗
PubMed1997

Genetic to genomic vaccination.

Our development of genetic immunization (unfortunately named 'DNA'-immunization at times) seems to have great promise as a vaccine delivery system. However, one is still left with the often formidable problem of discovering what gene of the pathogen to include in the genetic immunization vector. The is particularly a problem with pathogens with large genomes such as bacteria and parasites. We have developed a potential solution to this problem termed 'expression library immunization'. It involves using expression libraries in genetic immunization vectors to basically strip down the genome into protective genes. It may offer a systematic, unbiased approach to discover vaccine candidates.

Animals↗
PubMed1997

Semaphorin III can repulse and inhibit adult sensory afferents in vivo.

During development, semaphorins (collapsin, fasciclin) mediate repulsive and inhibitory guidance of neurons. Semaphorin III, a secretable member of this family, is expressed by the ventral spinal cord at the time corresponding to projection of sensory afferents from the dorsal root ganglion (DRG) into the spinal cord. The inhibitory effect of E14 ventral cord is active only on nerve growth factor (NGF)-responsive sensory afferents (small-diameter A-delta and C fibers subserving sensations of temperature and pain). Similarly, COS cells secreting recombinant semaphorin III are able to selectively repel DRG afferents whose growth is stimulated by NGF and not NT-3. However, it is not known whether these molecules can exert a functional role in the fully developed adult peripheral nervous system. In this study, we demonstrated that gene gun transfection and production of semaphorin III in corneal epithelial cells in adult rabbits in vivo can cause repulsion of established A-delta and C fiber trigeminal sensory afferents. In addition, it is shown that, following epithelial wounding and denervation, semaphorin III is able to inhibit collateral nerve sprouts from innervating the reepithelialized tissue. These findings are significant in that they provide direct evidence that small-diameter adult sensory neurons retain the ability to respond to semaphorin III. In addition, the corneal gene gun technique may be generally used to study the in vivo effects of neural growth modulators by quantifying the amount of sensory nerve growth.

Animals↗
PubMed1997

Controlled gene gun delivery and expression of DNA within the cornea.

Selective delivery of genes to ocular tissues in vivo has been a long sought after goal for potential gene therapy of ocular disease. The gene gun was considered for this purpose because of its ability to focally transfer DNA to cells through gold microparticles coated with DNA. Through experimentation, we optimized a technique that allows focal delivery and expression of a plasmid encoding green fluorescent protein in the corneal epithelium 100% of the time. Though the corneal epithelium has a delicate structure, this introduction was not associated with any corneal or ocular damage and did not produce any apparent ocular irritation. These findings demonstrate the utility of gene gun delivery of DNA to selected ocular tissues for potential experimental and therapeutic purposes.

Animals↗
PubMed1996

Recovery of chorda tympani nerve function following injury.

The chorda tympani (CT) nerve carries taste information from the anterior tongue to the brain stem. Injury to the chorda tympani may result in loss or distortion of taste information. This study examined changes occurring in the hamster peripheral taste system during recovery from injury. The hamster chorda tympani nerve was crushed in the middle ear and the animals were allowed to survive from 2 to 16 weeks. At 2 weeks, CT fibers had degenerated distal to the crush site. Up to 16 weeks after crush, there were 67% fewer myelinated fibers in regenerated nerves than in controls. The mean area of the Ca(2+)-ATPase-stained core of the fungiform taste buds was significantly smaller than in controls 2 weeks after injury, but recovered to control values by 4 weeks. Electrophysiological responses to taste stimuli were recorded from the chorda tympani distal to the injury. No responses were seen after 2 weeks; weak and unstable responses were seen after 3 weeks. By 4-8 weeks, relative responses to taste stimuli were similar to control responses, but the variability of the responses to sucrose was significantly greater than that in controls. The frequency of responses to the water rinse following taste stimuli, particularly sucrose, was also greater in the regenerated nerves. The abnormal electrophysiological responses to sucrose may be the result of the differential rate of return of fiber types and/or the transduction mechanisms. In some ways, recovery of the peripheral gustatory system after damage to the chorda tympani nerve recapitulates the later stages of taste bud development.

Animals↗
PubMed1996

Toward cell-targeting gene therapy vectors: selection of cell-binding peptides from random peptide-presenting phage libraries.

Ideal gene therapy vectors would be delivered intravenously to transfect only specific cells. Existing vectors only transfect cells in vivo in a manner determined by blood flow and the site of introduction. As a general and systematic approach for generating cell-targeting ligands for gene therapy vectors, we have used peptide-presenting phage libraries to select peptides that bind and enter several different cell types. Because of their small size, cell-binding peptides such as these could be incorporated into biological or physical gene therapy vectors. In addition, peptide-presenting phage themselves may also be candidates for gene therapy vectors.

Amino Acid Sequence↗
PubMed1996

Magnetic resonance imaging, histology, and x-ray of three stages of damage to the knees of STR/ORT mice.

RATIONALE AND OBJECTIVES: The authors develop a scoring system for assessing those features of degeneration of the STR/ORT mouse knee visualizable by magnetic resonance (MR) imaging, and to validate those MR scores by comparison with x-ray and histology. METHOD: Magnetic resonance imaging, histology, and x-ray have been used in a cross-sectional study to visualize the anatomy and pathology of the knees of three pairs of male STR/ORT mice and their approximately age-matched female pairs. A scoring system was developed that distinguished the faster rate of damage of the males from the slower progressive changes seen in the females. RESULTS: Changes in the patellar tendon were observed in MR imaging of the 5-month-old male knee. Sagittal images showed other degenerative features such as sclerosis and loss of signal from synovial fluid after 9 months; osteophytes and degeneration of the tibial plateau were better visualized in the coronal plane. Cysts were poorly correlated to the progression of the disease. Similar trends were observed for four features scored in x-rays (sclerosis, joint space narrowing, cysts, and osteophytes) and cartilage degradation assessed using histology. In contrast, the age-matched females were less affected. CONCLUSIONS: Magnetic resonance imaging can identify joint degeneration in the knees of male mice, which develops more rapidly than in age-matched females. Those observations were validated by radiology and histology.

Animals↗
PubMed1996

Effects of chorda tympani transection on long-term salt preference in hamsters.

The effects of denervation of fungiform taste buds on preference behavior were studied. Presurgery, 0.01, 0.1, 0.2, and 0.4 M NaCl, and 0.1, 0.2, and 0.4 M KCl were strongly avoided relative to water as measured with 48-h intakes. Bilateral cuts of the chorda tympani nerve (CT) resulted in a decrease in the strength of aversions to all concentrations of NaCl and to 0.2 and 0.4 M KCl. Only 0.4 M NaCl and KCl were strongly avoided after CT section. After CT section, when the animals were allowed to choose between equimolar (0.1 or 0.2 M) KCl and NaCl, they drank equal amounts, whereas intact hamsters preferred KCl to NaCl. In golden hamsters, unlike most laboratory rat strains, intake-based long-term preference behavior for salts is significantly affected by selective gustatory deafferentation.

Animals↗
PubMed1995

Protection against mycoplasma infection using expression-library immunization.

As is evident from the human immunodeficiency virus epidemic, there is no systematic method for producing a vaccine. Genetic immunization is a new approach to vaccine production that has many of the advantages of live/attenuated pathogens but no risk of infection. It involves introducing DNA encoding a pathogen protein into host cells and has shown promise in several disease models. Here we describe a new method for vaccine development, expression-library immunization, which makes use of the technique of genetic immunization and the fact that all the antigens of a pathogen are encoded in its DNA. An expression library of pathogen DNA is used to immunize a host thereby producing the effects of antigen presentation of a live vaccine without the risk. We show that even partial expression libraries made from the DNA of Mycoplasma pulmonis, a natural pathogen in rodents, provide protection against challenge from the pathogen. Expression library immunization may prove to be a general method for vaccination against any pathogen.

Animals↗
PubMed1995

Protection against Mycoplasma pulmonis infection by genetic vaccination.

The induction of an immune response against a foreign protein usually requires purification of that protein, which is injected into animals. The isolation of pure protein is time consuming and costly. Recently, a technique called biolistic transformation (biological ballistic system) microparticle injection, gene gun, or particle bombardment was developed. The basic idea is that DNA or biological material coated onto heavy tungsten or gold particles is shot into target cells or animals. We have vaccinated mice by introducing the gene (Mycoplasma pulmonis DNA or a specific fragment) encoding a protein recognized by a protective monoclonal antibody directly into the skin or muscle of mice by two methods: (i) using a hand-held form of the biolistic system that can propel DNA-coated gold microprojectiles (2 micrograms of DNA) directly into the skin; (ii) using a conventional intramuscular injection of the DNA (100 micrograms) into quadricep muscles of transfected mice. HeLa cells were transfected in vitro by the gene gun or by the liposomal delivery system. Indirect immuno-fluorescent antibody (IFA) assay of culture cells indicated that both methods could be successful. Production of antibody and cell-mediated immunity against M.pulmonis were monitored by assaying serum IFA and enzyme-linked immunosorbent assay (ELISA), and delayed type hypersensitivity. In addition, macrophage migration inhibition and lymphocyte transformation to antigen in spleen cells were also tested. Both delivery systems induced humoral and cellular immunity, and vaccinated the mice against infection. Genetic immunization by using the gene gun saves time, money, and labor; moreover, this general method is also applicable to gene therapy.

Animals↗
PubMed1995

Visualizing taste papillae in vivo with scanning electron microscopy of a high resolution cast.

A method using polyvinylsiloxane (PVS), a high-resolution dental impression material, to obtain negative images of lingual surfaces is described. Epoxy-resin tongue replicas made from these impressions were examined with scanning electron microscopy (SEM). This method has been developed to visualize structural details of the tongue surface of living human beings and laboratory animals. The utility of the method is demonstrated with hamster tongues, which have well-defined fungiform papillae with single taste pores, and human tongues, which have more variable surface structures. Replicas made from PVS impressions of tongues of living hamsters were compared with the same tongues after fixation. The replicas contained much of the detail present in fixed tongues. With SEM, it was possible to identify individual fungiform papillae, which contained depressions with the size and the location of hamster taste pores. Individual papillae could also be recognized in human-tongue replicas, but taste pores could not be identified with certainty. These replicas provide permanent, three-dimensional records of tongue topography that could be used to document changes due to trauma, disease and aging.

Animals↗
PubMed1995

Magnetic resonance imaging protocol optimization for evaluation of hyaline cartilage in the distal interphalangeal joint of fingers.

RATIONALE AND OBJECTIVES: To identify a single magnetic resonance imaging (MRI) protocol that will provide optimal signal-to-noise ratio, resolution, and image contrast with minimal susceptibility artifacts and that will allow clear delineation and visualization of cartilage, fluid, bone, tendons, and ligaments within the distal interphalangeal (DIP) joint of the human hand. METHODS: A highly optimized 2.4 T MRI system was constructed from a 31-cm horizontal bore magnet, using a solenoid radiofrequency coil. This was used to study the DIP joints of 16 healthy, asymptomatic volunteers. RESULTS: A range of image contrast protocols were explored, including spin-echo T1 and T2, field echo, chemical shift suppression to give water only images, and magnetization transfer. Susceptibility variations were explored by changing the field strength from 0.6 to 2.4 T. A spin-echo protocol with TR = 1500 msec and TE = 30 msec can routinely produce images with resolution 0.075 x 0.150 for a slice thickness of 1 mm in 13 minutes. That protocol can visualize simultaneously compact and trabecular bone, two layers of cartilage, synovial fluid, and synovium within the joint, tendons and ligaments, and the volar plate. CONCLUSIONS: Although the contrast is not fully optimized for any one tissue, the spin echo protocol (TR = 1500, TE = 30) provides sagittal MR images, which clearly delineate the major structures of interest within the DIP joint, and which will be used in future studies to compare changes in the DIP joint because of aging or osteoarthritis. Experience gained by applying the above methods to a total of 16 healthy, asymptomatic volunteers has enabled a single sequence to be identified, which although not optimized for any one tissue, nevertheless visualized simultaneously and clearly delineated compact and trabecular bone, two layers of cartilage, synovial fluid, and synovium within the joint.

Adult↗
PubMed1994

Effect of energy conservation and joint protection education in rheumatoid arthritis.

As there is relatively little information about the effectiveness of occupational therapy (OT) in RA a questionnaire was devised to assess whether patient knowledge and performance of joint protection manoeuvres improved following OT intervention and, if improved, whether this was sustained over 6 months. A photographic multiple choice questionnaire was devised covering major categories of activities of daily living. The study population consisted of 55 patients with RA attending a rheumatology clinic who had not previously had OT treatment. Patients had a single instruction/treatment session with an occupational therapist of 1-h duration. Prior to treatment the questionnaire was administered by an independent assessor who re-administered the questionnaire 1 month and 6 months after the OT session. Following treatment there was a significant increase in scores at 1 month compared with pre-treatment (P < 0.001). There was no significant change in score at 6 months compared with 1 month. Qualitative analysis of age and sex showed no significant effects. OT leads to sustained improvement in patient knowledge and probably performance of joint protection manoeuvres in RA.

Adult↗
PubMed1994

Production of monoclonal antibodies by genetic immunization.

Genetic immunization is a simple method for producing polyclonal antibodies in mice. To test if this approach could be used for monoclonal antibody production, biolistic transfection was used to immunize a mouse. High levels of polyclonal antibodies against human growth hormone (hGH) were elicited following three inoculations with the gene for hGH. When hybridoma cells were created from the mouse's splenocytes, approximately 17% secreted antibodies vs. hGH. Of these, some recognized only native or denatured hGH, while most recognized both forms of the protein. These findings demonstrate the utility of genetic immunization as a method to produce monoclonal antibodies.

Animals↗
PubMed1993

Organization of the nucleus of the solitary tract in the hamster: acetylcholinesterase, NADH dehydrogenase, and cytochrome oxidase histochemistry.

The distribution of acetylcholinesterase (AChE), NADH dehydrogenase (NADHd), and cytochrome oxidase (CO) was determined in the nucleus of the solitary tract (NST) in the golden hamster. Histochemical staining was compared to cytoarchitectonic subdivisions of the NST (Whitehead: J. Comp. Neurol. 276:547-572, 1988) and to terminal fields of primary afferents of the nerves that innervate the tongue. These three histochemical methods resulted in differential staining patterns within the NST that were related to certain subdivisions. Transganglionic transport of horseradish peroxidase (HRP) was used to determine the central projections of the chorda tympani (CT), the lingual branch of the trigeminal (L-V), and the lingual-tonsilar branch of the glossopharyngeal nerves (L-IX). Alternate or the same brain sections were processed to reveal transported HRP, and NADHd or AChE levels. Increased staining of the neuropil with NADHd and AChE was coincident with the dense part of the afferent terminal fields of all three nerves in the NST and the laterally adjacent dorsomedial part of the spinal trigeminal nucleus. CO showed this pattern only for the most rostral part of the CT field. The densest AChE staining coincided with gustatory afferent terminal fields. The histochemical staining facilitated the interpretation of the organization of the NST. For example, at caudal levels of the gustatory NST, it is suggested that taste processing is localized predominantly in the medial part of the rostral central, and somatosensory processing in the rostral lateral subdivision. AChE or NADHd staining should facilitate studies of connections, topography, and neuroplastic changes of the gustatory NST.

Acetylcholinesterase↗
PubMed1993

Etoposide-induced apoptosis in human HL-60 cells is associated with intracellular acidification.

Apoptosis is a pathway of cell death characterized by internucleosomal digestion of genomic DNA. Such DNA digestion can be induced by both physiological stimuli and cytotoxic treatment with many anticancer agents. This digestion has generally been considered to be mediated by a Ca2+/Mg(2+)-dependent endonuclease that is activated by increases in intracellular Ca2+. However, we suggest that an alternate endonuclease, DNase II, may be a more likely candidate. In these studies, apoptosis was induced in human HL-60 cells by a 30-min incubation with the topoisomerase II inhibitor etoposide. DNA digestion characteristic of apoptosis began within 3 h of removal of etoposide. Morphological indication of apoptosis was observed concurrently. Only about 20% of the cells underwent apoptosis at this time; these appeared to be cells in S phase at the time of etoposide treatment. The remainder of the cells progressed to the G2 phase and arrested there for at least 48 h. Intracellular Ca2+ and pH were measured in individual cells by flow cytometry. No changes in intracellular Ca2+ were observed, but an acidification of up to 1 pH unit occurred in about 15% of the cells and correlated with the time course of appearance of DNA digestion. Cells were sorted on the basis of intracellular pH and only the acidic cells showed the morphology and DNA digestion characteristic of apoptosis. These results demonstrate the involvement of DNase II in apoptotic DNA digestion and suggest mechanisms of pH homeostasis as regulators of apoptosis.

Apoptosis↗