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J F Griffin

Publications and source records attributed to J F Griffin.

At least 19 recordsLinked to original sources
PubMed1999

Intracellular survival of virulent Mycobacterium bovis and M. bovis BCG in ferret macrophages.

The intracellular survival of virulent Mycobacterium bovis and avirulent M. bovis BCG in ferret alveolar macrophages was investigated. In addition, the effects of endogenous and exogenous modulators of macrophage oxidative function on bacterial survival and growth in vitro were determined. Ferret macrophages limited the initial growth of BCG, while virulent M. bovis replicated within macrophages. Intracellular bacterial survival was unaffected by the addition of specific inhibitors of macrophage oxidative function. A T-cell supernatant (TCS), derived from mitogen-stimulated lymphocyte cultures, activated ferret macrophages for heightened oxidative burst performance. However, macrophages activated by TCS, bacterial LPS or a combination of both, failed to control infection, and actually enhanced the intracellular survival of M. bovis. These results are discussed in relation to the role of macrophages in mediating tuberculosis-related pathogenesis, with respect to the fact that ferrets are important wildlife vectors of bovine tuberculosis in New Zealand.

Animals↗
PubMed1999

The effect of a Medicaid managed care program on the adequacy of prenatal care utilization in Rhode Island.

OBJECTIVES: The purpose of this study was to determine whether adequacy of prenatal care utilization improved after the implementation of a Medicaid managed care program in Rhode Island. METHODS: Rhode Island birth certificate data (1993-1995; n = 37021) were used to analyze pre- and post-program implementation changes in adequacy of prenatal care utilization. Logistic regression models were used to characterize the variation in prenatal care adequacy as a function of both time and the various covariates. RESULTS: Adequacy of prenatal care utilization for Medicaid patients improved significantly after implementation of the program, from 57.1% to 62.1% (odds ratio [OR] = 1.2, 95% confidence interval [CI] = 1.1, 1.3). After the program was implemented, Medicaid patients who went to private physicians' offices for prenatal care were 1.4 times as likely as before to receive adequate prenatal care (OR = 1.4, 95% CI = 1.2, 1.7). CONCLUSIONS: Unlike many other Medicaid expansions for pregnant women, the RIte Care program in Rhode Island has resulted in significant improvement in adequacy of prenatal care utilization for its enrollees. This improvement was due to specific program interventions that addressed and changed organizational and delivery system barriers to care.

Adolescent↗
PubMed1998

Farmed deer: a large animal model for stress.

In the early classic period it was suggested by Heracleitus that a static unchanged state was not the natural condition, but rather that the capacity to undergo constant change was intrinsic to all living things. After that, Empedoeles, circa 500 BC, proposed that for living organisms to survive they require a harmonious mixture of elements. Hippocrates, around 400 BC, developed this concept further by suggesting that health is a state of harmonious balance of these elements, equating disease to a state of disharmony and introducing the concept that nature heals disease (Noysvn Fyseiw/atrui). Soon after, Epicurus extended these ideas to include among these healing forces, the mind, writing that imperturbability of mind is desirable. Claude Bernard introduced the concept of the milieu interieur or the internal physiologic environment, describing its constancy as essential in an external environment typified by its variability. Walter Cannon described Bernard's constancy as Homeostasis and identified the "fight or flight reflex," linking the adaptive response and catecholamine secretion, with extreme levels of activation-producing pathology. Selye outlined four stages of the stress response: 1) the "alarm reaction" characterized by an immediate activation of the sympathetic-adrenomedullary axis (SA); 2) a "resistance phase" characterized by hypothalamic pituitary-adrenal axis (HPA) activation; 3) a stage of adrenal hypertrophy, gastrointestinal ulceration, along with thymic and lymphoid atrophy; and 4) an exhaustion phase and finally death (1).

Animal Husbandry↗
PubMed1998

A long-lasting interferon-gamma response is induced to a single inoculation of antigen-pulsed dendritic cells.

Vaccines against infectious organisms must produce not only long-lasting immunity but also the appropriate immune response to clear the infection. Obligate intracellular parasites, such as mycobacteria, require a predominantly cell-mediated immune response rather than antibody. Presentation of antigen by dendritic cells (DC) has been associated with the development of strong cell-mediated responses generating the production of interferon-gamma (IFN-gamma). This cytokine has an essential role in the elimination of mycobacteria. Therefore, we investigated both the duration and the nature of the immune response after priming with DC pulsed with mycobacterial antigen and compared this with priming using a conventional adjuvant. We used two strains of mice: C57BL/6, which inherently produces a T-helper 1 (Th1)-type response to mycobacterial antigen, and BALB/c, which does not. DC-enriched cell suspensions, purified DC or cultured bone marrow cells resembling DC (BMAPC) were prepared, pulsed overnight with PPD and injected intravenously (i.v.) into naive mice. Six and 12 weeks later, splenic T lymphocytes from these mice were challenged in vitro with antigen and their proliferative response and cytokine production was determined. Significant antigen-specific proliferation was observed in all assays on rechallenge with antigen in vitro 6 and 12 weeks after the initial priming with DC. IFN-gamma was detected in both strains but was only antigen specific in the C57BL/6 strain. Purified protein derivative (PPD)-pulsed BMAPC generated similar responses 6 weeks after priming. Thus, long-term T-lymphocyte responses and the production of IFN-gamma can be generated using a single inoculation of PPD-pulsed DC.

Animals↗
PubMed1996

Opioid antagonist activity of naltrexone-derived bivalent ligands: importance of a properly oriented molecular scaffold to guide "address" recognition at kappa opioid receptors.

The presence of a molecular scaffold to orient a basic group is important for potent and selective kappa opioid antagonist selectivity. An attempt to determine how the geometry of the scaffold affects this selectivity has led to the synthesis of a bivalent ligand (5) whose linker constrains the N17' basic nitrogen (the "address") to a position that is 6.5 A from N17' in the kappa antagonist norBNI (1) when these molecules are superimposed. The fact that compound 5 was found to be a highly selective and potent mu-selective antagonist supports the idea that the position of N17' in 5 precludes effective ion pairing with the nonconserved residue Glu297 on outer loop 3 of the kappa opioid receptor. The high mu receptor binding affinity and in vitro pharmacological selectivity of 5 coupled with its presumed low central nervous system bioavailability suggest that it may be a useful antagonist for the investigation of peripheral mu opioid receptors.

Animals↗
PubMed1996

Molecular structure and mechanisms of action of cyclic and linear ion transport antibiotics.

Ionophores are antibiotics that induce ion transport across natural and artificial membranes. The specific function of a given ionophore depends upon its selectivity and the kinetics of ion capture, transport, and release. Systematic studies of complexed and uncomplexed forms of linear and cyclic ionophores provide insight into molecular mechanisms of ion capture and release and the basis for ion selectivity. The cyclic dodecadepsipeptide valinomycin, cyclo[(-L-Val-D-Hyi-D-Val-L-Lac)3-], transports potassium ions across cellular membrane bilayers selectively. The x-ray crystallographic and nmr spectroscopic data concerning the structures of Na+, K+, and Ba+2 complexes are consistent and provide a rationale for the K+ selectivity of valinomycin. Three significantly different conformations of valinomycin are observed in anhydrous crystals, in hydrated crystals grown from dimethylsulfoxide, and in crystals grown from dioxane. Each of these conformations suggests a different mechanism of ion capture. One of the observed conformations has an elliptical structure stabilized by four 4<--1 intramolecular hydrogen bonds and two 5<--1 hydrogen bonds. Ion capture could be readily achieved by disruption of the 5<--1 hydrogen bonds to permit coordination to a potassium ion entering the cavity. The conformation found in crystals obtained from dimethyl sulfoxide is an open flower shape having three petals and three 4<--1 hydrogen bonds. Complexation could proceed by a closing up of the three petals of the flower around the desolvating ion. In the third form, water molecules reside in the central cavity of a bracelet structure having six 4<--1 hydrogen bonds. Two of these bracelets stack over one another with their valine-rich faces surrounding a dioxane molecule. The stacked molecules form a channel approximately 20 A in length, suggesting that under certain circumstances valinomycin might function as a channel. A series of analogues of valinomycin differing in ring composition and size have been synthesized and their transport properties tested. Peptide substitution and chiral variation in the dodecadepsipeptide can result in stabilization or modification of the different conformers. While contraction of the ring size results in loss of ion transport properties, expansion of the ring size permits complexation of larger ions and small positively charged molecules. Gramicidin A is a pentadecapeptide that functions as a transmembrane channel for transporting monovalent cations. Crystal structures of the cesium chloride complex and two uncomplexed forms of gramicidin A have been reported. In all three structures the gramicidin A molecule is a left-handed, antiparallel, double-stranded helical dimer. In the cesium complex the beta 7.2-helix has 6.4 residues per turn with an internal cavity large enough to accommodate cesium ions. In the uncomplexed structures the channel is 31 A long and has 5.6 amino acids per turn. Because the helix is too tightly wound to permit ion transport, ion transport would require breaking and reforming of hydrogen bonds.

Amino Acid Sequence↗
PubMed1996

The cloning, expression and purification of cervine interleukin 2.

The cloning, sequencing and expression of cervine interleukin 2 (IL-2) is described. Cervine IL-2 cDNA is 489 base pairs long and shows high homology to bovine and ovine IL-2 (approximately 94%) with lower homologies to human (50%) and mouse (53%). The predicted protein sequence is 162 amino acids long with a signal sequence containing 20 amino acids. A molecular weight of 16273 Da was predicted for the mature protein. The expression plasmid pTRXFUS was redesigned to allow recombinant proteins to be expressed at high levels in a soluble form and subsequently affinity purified. This new plasmid, pTRXHIS, has been used to express the first cervine cytokine, IL-2. The fusion of the cervine IL-2 gene to the thioredoxin gene (TRX) stabilizes the recombinant product allowing the high expression of soluble IL-2. A polyHis (6 x Histidines) tag has been inserted between the two fusion partners which allows the fusion product to be affinity purified on a nickel-nitrilo-tri-acetic acid (Ni-NTA) column. The purified cervine IL-2 fusion protein was shown to be biologically active despite the presence of the TRX at the amino terminus. The TRX can be removed enzymatically with enterokinase releasing the biologically active IL-2 molecule. This expression system has several features that are useful in producing and purifying large quantities of biologically active cytokines.

Amino Acid Sequence↗
PubMed1996

Macrophage function in deer.

Macrophage inflammatory and immune functions were characterised in red deer (cervus elaphus), for use as a model for natural infection with bovine tuberculosis. Highly enriched populations of deer macrophages were obtained from 14 day cultures of plastic-adherent peripheral blood mononuclear cells. Cervine macrophages produced superoxide anion in response to respiratory burst stimuli (serum-opsonised zymosan and phorbol myristic acetate), but nitric oxide production could not be detected under the conditions tested. The lysosomal enzymes acid phosphatase and lysozyme were detected at the intercellular and extracellular level. Stimulation with bacterial lipopolysaccharide extract (Escherichia coli LPS) enhanced the production of superoxide and acid phosphatase with a peak increase in activity observed after 2h. Production of interleukin 1 (IL-1) and tumour necrosis factor (TNF), determined using cytokine-sensitive cell lines and mRNA analysis (Northern blotting), indicated maximal secretion of both cytokines after 24 h stimulation with LPS, preceded by a peak in message accumulation at 2-6 h post-stimulation. Cervine macrophages stimulated proliferative responses in T cell-enriched lymphocyte populations derived from the peripheral blood of autologous animals that had been primed to mycobacterial antigens (Mycobacterium bovis Bacille Calmette-Guerin, BCG). Macrophages were able to stimulate responses after pulsing with particulate (BCG) or soluble (purified protein derivative) mycobacterial antigens. These results indicate that macrophage inflammatory and immune responses in red deer are similar to those in other mammalian species, and that macrophages may play an important role in resistance to mycobacterial infection.

Animals↗
PubMed1996

In vitro responses of cervine macrophages to bacterial stimulants.

The function of cervine (deer) mononuclear phagocytes is poorly defined. In the present study, the potential of cervine macrophages to generate phagocytic and immunoregulatory responses following stimulation with bacterial products was investigated. Blood-derived macrophages of red deer were cultured in vitro with particulate stimulants (Mycobacterium bovis BCG and Staphylococcus aureus SAC) or soluble stimulants (M. bovis PPD and Escherichia coli LPS), prior to assessment of phagocytic responses, prostaglandin secretion and cytokine production. Particulate stimulants induced vigorous phagocytic responses (superoxide anion generation, lysosomal enzyme release), secretion of prostaglandin E2 and transcription of mRNA specific for the cytokines IL-1 beta, IL-10 and TNF alpha, while soluble products invoked weaker responses. These results are discussed in relation to the role of cervine mononuclear phagocytes in regulating and participating in inflammatory and immune processes relevant to bacterial challenge.

Animals↗
PubMed1996

The fascinating complexities of steroid-binding enzymes.

Enzymes that modulate the level of circulating steroid hormone can be used to combat steroid-dependent disorders. Members of the NADPH-dependent short chain dehydrogenase/reductase (SDR) family control blood pressure, fertility, and natural and neoplastic growth. Despite the fact that only one amino acid residue is strictly conserved in the 60 known members of the family, all appear to have the dinucleotide-binding Rossmann fold and homologous catalytic residues containing the conserved tyrosine. Variation in the amino acid composition of the substrate binding pocket creates specificity of binding for steroids, prostaglandins, sugars and alcohols. Licorice induces high blood pressure by inhibiting an SDR in the kidney, and appears to combat ulcers by inhibiting another in the stomach. Detailed X-ray analyses of various members of the family should allow the design of potent, tissue-specific, highly selective inhibitors.

Amino Acid Sequence↗
PubMed1996

T cell responses to Mycobacterium bovis in red deer, a large animal model for tuberculosis.

Red deer (Cervus elaphus) represent an appropriate large animal model to study the immunology of tuberculosis, being naturally susceptible to Mycobacterium bovis infection. Cell-mediated immune responses were investigated in deer displaying protective- or disease-type reactions, following immunization with M. bovis bacille Calmette-Guerin (BCG) or infection with virulent M. bovis, respectively. T cell responses were measured as antigen-dependent cell proliferation and production of T cell growth factor (TCGF) following in vitro stimulation with M. bovis antigens (live or heat-killed BCG, or PPD). T cells from immunized deer proliferated less in response to soluble denatured culture antigen (purified protein derivative, PPD) than to particulate BCG, although there were no differences in the magnitude of these responses between the two groups of animals. Cells derived from immunized deer produced less TCGF than cells from infected deer when stimulated with PPD in vitro, although responses to BCG antigens were similar between the two groups. The majority of TCGF activity was neutralized by anti-IL-2 antibodies, regardless of the animal group or source of antigen used for in vitro stimulation. After 7 days in vitro culture with antigen, blast cells staining positively for alpha beta (CD4, CD8) and gamma delta T cell receptors were recorded. The majority of blasts were CD4+, although in immunized deer fewer CD4+ blasts were produced following in vitro stimulation with PPD than with BCG antigens. These results, together with previous reports from our laboratory, represent the only detailed examinations of T cell responses to M. bovis in this naturally-susceptible ruminant species.

Animals↗
PubMed1995

Use of globic scattering factors for protein structures at low resolution.

At 3 to 4 A resolution, the electron density of a protein may be modeled by a continuous chain of 'globs' representing the amide region of the peptide backbone and the side-chain residues. Group scattering factors are derived from a trans planar C alpha C = ONC alpha backbone segment and most favored side-chain conformer for 18 different amino acids. Trial calculations indicate that the phase error and crystallographic residual comparing the atomic and 'globic' models rapidly decrease from high to low resolution. At 3 A resolution, the phase error is approximately 80 degrees. These results indicate that the electron density of a protein composed of N amino acid residues may be adequately modeled by 2N globs at low resolution.

Amino Acids↗
PubMed1995

Cloning and sequencing of expressed DRB genes of the red deer (Cervus elaphus) Mhc.

The expressed major histocompatibility complex (Mhc) class II DRB genes of 50 unrelated deer were examined by reverse transcription polymerase chain reaction, cloning, and sequencing of DRB exon 2. Deer, like other mammals, have at least one highly polymorphic Mhc class II DRB gene. Thirty-four different sequences were identified. Most of the variation in amino acid composition occurred at positions that have been shown to form the peptide binding site (PBS). Eighteen deer-specific substitutions were found, 11 of these occurred in the PBS. Significantly higher rates of replacement substitutions than silent substitutions were found in the deer sequences, indicating strong positive selection pressure for diversity in DRB sequences. Between one and four DRB sequences were found per deer. Inheritance of these sequences in pedigrees showed Mendelian segregation with up to two expressed DRB genes per haplotype. Sheep are the only other ruminant in which the presence of more than one expressed DRB gene has been demonstrated. Phylogenetic trees were constructed in an attempt to assign the deer DRB sequences to specific loci, but no clear segregation of the DRB sequences for different loci was found. It would seem likely that sequence exchange between the loci has occurred. As has been shown in other species, the alpha-helix and beta-sheet regions of exon 2 appeared to have different evolutionary histories.

Amino Acid Sequence↗
PubMed1995

Animal models of protective immunity in tuberculosis to evaluate candidate vaccines.

While the etiology of tuberculosis is well understood, the nature of the protective immune response to the causative mycobacteria has remained a mystery. There is an urgent need to define protective immunity critically, and to develop alternative animal models to evaluate the efficacy of new-generation vaccines against tuberculosis in a cost-effective way.

Animals↗
PubMed1995

Ocular trauma: evaluation with US.

PURPOSE: To examine the value of real-time ultrasonography (US) in the assessment of traumatized eyes with opaque ocular media. MATERIALS AND METHODS: Sixty-one eyes in 60 patients were prospectively examined with US; findings were correlated with findings of clinical and surgical follow-up. Patients with an intraocular foreign body (IOFB) also underwent computed tomography (CT). RESULTS: US demonstrated 56 vitreous hemorrhages, 21 retinal detachments, 12 vitreous detachments, five choroidal detachments, seven IOFBs, three dislocated lenses, and two retrohyaloid hemorrhages. Findings of US and surgery or clinical follow-up were in complete concurrence in 55 cases (90%) and partial concurrence in two cases (3%). US findings were incorrect in four cases (7%). In four cases, US allowed diagnoses that were unsuspected clinically. CONCLUSION: US accurately demonstrates ocular damage and may reveal unsuspected problems. US was superior to CT in demonstration of intraocular damage associated with IOFBs, although CT was superior in determination of the size and site of the IOFB. The presence of dense vitreous traction bands may indicate impending retinal detachment.

Adult↗
PubMed1994

The influence of maternal separation on humoral and cellular immunity in farmed deer.

The effect of maternal separation on in vivo and in vitro immune parameters was studied in young hybrid deer. Groups of fawns separated from their mothers either 2 days prior to or 7 days post immunization with keyhole limpet hemocyanin were compared with a control group of immunized, unseparated fawns. Animals separated prior to antigenic challenge had significantly higher concentrations of antigen-specific IgG in their serum than control animals. There was no influence on the humoral immune response in animals separated following immunization. In contrast, Con A transformations were transiently depressed in separated animals compared to the control group. The time separation was imposed relative to challenge and therefore influenced the subsequent immune response.

Animals↗
PubMed1994

Aetiology, pathogenesis and diagnosis of Mycobacterium bovis in deer.

Tuberculosis, caused by Mycobacterium bovis, is emerging as the most important disease affecting farmed deer. While the disease is usually found at a low incidence involving lesions in single lymph nodes, it may present as a rapidly spreading, fulminating disease, especially in animals exposed to stress. The unique susceptibility of cervidae to mycobacteria in general has meant that diagnosis of tuberculosis in deer using conventional intradermal tuberculin tests may be unsatisfactory. Tuberculin testing in deer is more technically demanding than in cattle, with the cervical region being the most sensitive area. False positive skin reactions occur widely in non-diseased deer while seriously infected animals may be "anergic" and fail to react (false negative). Comparative cervical tests have been used to improve test specificity but they suffer from reduced levels of sensitivity. A new blood test for tuberculosis (BTB) has been developed specifically for deer. This assay uses a combination of laboratory tests which measure lymphocyte transformation, antibody and inflammation. The composite BTB has a sensitivity of > 95% and a specificity of > 98% for diagnosis of M. bovis in cervidae.

Animals↗