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PubMed1984

Use of bacteria and yeasts to identify T lymphocytes in peripheral blood and lymphoid tissues of healthy guinea pigs and guinea pigs fed aflatoxin.

Fifty-four bacterial and 10 yeast isolates were screened to identify strains that were consistently bound by peripheral blood lymphocytes (PBL) of guinea pigs. None of the yeast isolates examined was bound by guinea pig PBL. Of 54 bacterial isolates, 10 were bound by greater than 5% of PBL. Potential lymphocyte markers from these bacteria were chosen for further study. Sodium azide inhibited the binding of bacteria by PBL. Preparations of T lymphocytes indicated that Salmonella schottmuelleri was bound by most T lymphocytes; Yersinia enterocolitica was bound by a subpopulation of T lymphocytes. Patterns of binding of bacteria by lymphocytes from thymus, lymph node, or spleen differed from binding patterns obtained using PBL. Aflatoxin did not affect the total WBC, differential leukocyte count, absolute lymphocyte count, or relative percentage of PCV of guinea pigs given as much as 0.060 mg of aflatoxin B1 equivalents/kg of body weight/day for 3 weeks. Changes in absolute numbers of peripheral blood T lymphocytes were not observed in guinea pigs given aflatoxin when immunofluorescence or bacterial binding was used to identify lymphocyte populations, except that the number of S schottmuelleri-binding lymphocytes (tentatively identified as T lymphocytes) in guinea pigs given the highest dose of aflatoxin (0.060 mg of aflatoxin B1 equivalents/kg/day) was less than the number of T lymphocytes identified by immunofluorescence.

Aflatoxin B1↗
PubMed1993

[The establishment of a monolayer culture system of guinea pig chief cells and an enzyme immunoassay system for guinea pig pepsinogen].

For the purpose of studying pepsinogen secretion from gastric chief cells, we established a monolayer culture system of guinea pig chief cells and an enzyme immunoassay (EIA) system specific for guinea pig pepsinogen. Dispersed chief cells were obtained from gastric mucosa of a guinea pig using collagenase, GEDTA, and Percoll solution, suspended in DMEM/F-12 (1/1 containing 10% FCS) media, and cultured for 70hr. Then the monolayer culture system was established. Pepsinogen was purified from gastric mucosa of a guinea pig using DEAE-Sephacel and Sephacryl S-200 columns. Antibody to pepsinogen was raised by immunizing rabbit with the purified pepsinogen. A two-site EIA system was then established using beta-galactosidase-labeled Fab' antibody. The EIA system showed sensitivity to measure above 1.5ng of guinea pig pepsinogen, and the monolayer culture system responded well to secretagogues. These systems are useful for studying pepsinogen secretion.

Animals↗
PubMed1983

Protection of Lassa virus-infected guinea pigs with Lassa-immune plasma of guinea pig, primate, and human origin.

Lassa virus-immune plasma has been used to treat human Lassa fever patients; however, criteria for plasma selection were based arbitrarily on available serologic tools and protective efficacy was never directly assessed. To test the validity of plasma therapy for Lassa virus infections in an animal model, and to develop biologically relevant criteria for selection of protective immune plasma, inbred, strain 13 guinea pigs were infected with a lethal dose of Lassa virus and treated with various Lassa-immune plasmas obtained from guinea pigs, primates, and convalescent human patients. Neutralizing antibody titers were determined in a virus dilution, plaque reduction test, and were expressed as a log10 plaque-forming units (PFU) neutralization index (LNI). All guinea pigs treated with immune plasma 6 ml/kg/treatment on days 0, 3, and 6 after virus inoculation were protected, provided the LNI exceeded 2.0. Plasmas obtained from donors in early convalescence (32-45 days) had low titers of N-antibody (LNI less than 2) and failed to confer protection, despite high titers of Lassa antibody measured in the indirect fluorescent antibody (IFA) test. Higher doses of marginally titered plasma conferred increased protection. The degree of protection and suppression of viremia was closely associated with LNI an not IFA titers. Administration of low-titered plasma did not result in immune enhancement. A high dose of human plasma from Liberia (12 ml/kg/treatment) was required to confer complete protection to guinea pigs infected with a Lassa virus strain from Sierra Leone (LNI = 1.6), while a lower dose (3 ml/kg/treatment) was sufficient for protection against a Liberian strain (LNI = 2.8), suggesting that a geographic matching of immune plasma and Lassa virus strain origin may increase treatment success. These studies support the concept of plasma therapy for Lassa infection and suggest that the plaque reduction neutralization test is more appropriate than the IFA test for predicting protective efficacy of passively administered plasma.

Animals↗
PubMed1990

High-density lipoprotein binding to guinea-pig hepatic membranes. Comparison of guinea-pig and human ligands.

Human and guinea-pig apo-E-free HDL were incubated with isolated guinea-pig hepatic membranes at 4 and 37 degrees C to determine the effects of temperature and heterologous systems on the equilibrium parameters of HDL binding. Receptor mediated HDL binding was highest at 37 degrees C for both lipoproteins. At 4 degrees C, a higher affinity constant (Kd) was observed when guinea-pig HDL was the ligand relative to human HDL; in contrast, both HDL preparations had similar Kd values at 37 degrees C. Calculated binding and receptor number (Bmax) were higher at both temperatures when guinea-pig HDL was the ligand. These results demonstrate a significant species difference in HDL binding to hepatic membrane which is partially temperature-dependent.

Animals↗
PubMed1990

Regulatory system of guinea-pig complement C3b: two factor I-cofactor proteins on guinea-pig peritoneal granulocytes.

Complement factor I is a plasma protease serving for proteolytic inactivation of C3b together with its cofactor. We have identified two factor I-cofactor activities in solubilized extracts of guinea-pig peritoneal granulocytes using guinea-pig factor I (Igp) and fluorescent-labeled methylamine-treated guinea-pig C3 (f-C3(MA)gp). One of these eluted from a chromatofocusing column between pH 7.6-7.1, and the other at about pH 5.7. These two cofactor fractions both interacted with Igp and, to a lesser degree, with human factor I (Ihu) on C3(MA)gp cleaving it into an inactive C3bi analogue, but did not cleave methylamine-treated human C3 (C3(MA)hu) together with Igp or Ihu. These factors are therefore species specific. The neutral and acidic fractions with cofactor activity contained C3(MA)gp-binding proteins with a doublet of 55 kDa and 42 kDa, and a singlet of 160 kDa, respectively, on SDS-PAGE. These proteins may be membrane cofactor protein (MCP) and C3b/C4b receptor (CR1) of guinea-pigs.

Animals↗
PubMed1993

Comparison of kappa 2-opioid receptors in guinea pig brain and guinea pig ileum membranes.

The presence of kappa-opioid receptor subtypes has been clearly established in guinea pig brain. Using [3H]bremazocine in the presence of reversible blockers of mu, delta and kappa 1 receptors, two additional binding sites can be determined in guinea pig brain membranes. The site with higher affinity for the opioid ligands represents kappa 2, while the other site has low affinity and is poorly characterized. The kappa 2 site has high affinity for ethylketocyclazocine and other benzomorphans, as well as for the dynorphin gene products tested. The dynorphin analogs have no appreciable affinity for the low affinity site, so this site should not be called a kappa receptor. With an appropriate membrane preparation, kappa 2 binding can also be demonstrated in the guinea pig ileum. Binding affinities for selected ligands at kappa 2 in guinea pig ileum membranes are very similar to affinities found in brain membranes.

Analgesics↗
PubMedDate not supplied

Regulatory system of guinea-pig complement C3b: tests for compatibility of guinea-pig factors H and I with human factors.

Two proteins that are involved in cleavage of methylamine-treated C3 of guinea-pig origin (C3(MA)gp) have been isolated from guinea-pig serum. One of them functioned as a cofactor of human factor I (Ihu) for cleavage of C3(MA)gp and its molecular size was 150 kDa. The other was functionally pure and able to cleave C3(MA)gp together with human factor H (Hhu). They appear to be analogous to human factors H and I in the guinea-pig and will be referred to as Hgp and Igp. Methylamine-treated human C3 [C3(MA)hu] was not a compatible substrate for Hgp or Igp: little cleavage of C3(MA)hu was observed if human factor H (Hhu) or I was substituted with the guinea-pig counterpart. C3(MA)gp, on the other hand, served as a substrate, though less efficiently, for Hhu and Ihu. Human C4b-binding protein (C4bp) and membrane cofactor protein (MCP) as well as Hhu could participate in cleavage of C3(MA)gp by Igp or Ihu. In these assays, C3(MA)gp was degraded again less efficiently than C3(MA)hu. Interestingly, human C3b/C4b receptor (CR1) mediated factor I-dependent cleavage of C3(MA)hu and C3(MA)gp to a similar extent regardless the sources of factor I. These results suggest that factor I-dependent C3b regulatory system is species-specific except in the case of CR1, which may function as a cofactor irrespective of species.

Animals↗
PubMed2005

Auditory thalamus responses to guinea-pig vocalizations: a comparison between rat and guinea-pig.

Although neuronal responses to species-specific vocalizations have long been described, very few between-species comparisons have been made. In a previous study, a differential representation of species-specific vocalizations was found in the auditory cortex (ACx): marmoset ACx neurons responded more, and more selectively, to marmoset calls than did cat ACx neurons [Wang, X., Kadia, S.C., 2001. Differential representation of species-specific primate vocalizations in the auditory cortices of marmoset and cat. J. Neurophysiol. 86, 2616-2620]. The present study analyzed responses of guinea-pig and rat auditory thalamus neurons to four well-defined guinea-pig vocalizations. Neurons of guinea-pigs (n = 96) and rats (n = 87) displayed similar response strength to guinea-pig vocalizations, and did not exhibit a preference for the natural over the time-reversed version of the calls in both species. This difference with the study by Wang and Kadia might suggest that, in mammals, the selectivity for the natural version of species-specific vocalizations is prominent only at the cortical level.

Animals↗
PubMed2006

Recombinant guinea pig TNF-alpha enhances antigen-specific type 1 T lymphocyte activation in guinea pig splenocytes.

TNF-alpha is a principal pro-inflammatory cytokine which contributes to the activation of innate immunity and the transition to antigen-specific adaptive immunity in tuberculosis. Using recombinant guinea pig (rgp) TNF-alpha, the effect of TNF-alpha on lymphocyte activation was examined in unvaccinated and BCG-vaccinated guinea pigs. Splenocytes were stimulated with PPD or ConA, in the presence or absence of rgp TNF-alpha for 96 h. Lymphocyte proliferation was measured using [(3)H]thymidine uptake, and IL-12 p40 and IFN-gamma mRNA were analyzed using real-time PCR. rgpTNF-alpha alone was able to stimulate a significant degree of proliferation in splenocytes. The addition of rgpTNF-alpha to PPD-stimulated cells enhanced the proliferation of splenocytes from BCG-vaccinated guinea pigs. Furthermore, enhancement of proliferation by rgpTNF-alpha was found to be correlated with upregulation of the levels of Type 1 cytokine mRNA (IL-12p40 and IFN-gamma) in splenocyte cultures. This suggests that TNF-alpha plays an important role in the regulation of Type 1 T cell-mediated immune responses in the guinea pig.

Animals↗
PubMed1977

Cytotoxicity of guinea-pig lymphoid cells against guinea-pig hepatoma cells in tissue culture.

The cytotoxic effect of guinea-pig lymphoid cells on guinea-pig hepatoma cell lines in tissue culture was investigated, using the microplate technique of Takasugi and Klein (1970). The effect of lymphoid cells from guinea-pigs immunized against tumor cells was compared to that of cells from normal controls. Several ratios of effector to target cells (10 : 1, 50 : 1, 150: 1, 250 : 1) were used. In Hartley guinea-pigs immunized with allogeneic tumour cells, peripheral blood lymphoid cells from 14/16 animals showed significant cytotoxicity against that tumour in culture. In a syngeneic tumour/host system, 7/13 animals showed cytotoxicity. Spleen cells gave less consistent results in both systems. The cytotoxic activity of subpopulations of immune lymphocytes against tumour cells in vitro was investigated. It was found that although both T-cell-enriched and T-cell-depleted cell populations exhibited cytotoxicity against tumour cells, the unfractionated cell population was the most effective. This suggests that some degree of cell cooperation may be involved in the cytotoxicity. Antibody-dependent cellular cytotoxicity was also obtained. A T-cell-depleted population of normal cells was shown to be cytotoxic to tumour cells in the presence of serum from immune animals. This type of cytotoxicity could be obtained concomitantly with cell-mediated cytotoxicity in the same animals.

Animals↗
PubMed2006

Effect of 1-acyl-5,6-dialkoxy-2-alkylthiobenzo[d] imidazoles on the action potential duration and isometric contraction in guinea pig atrium activated by carbachol and in guinea pig heart papillary muscles.

BACKGROUND: Studies have shown that some benzo[d]imidazole derivatives (1-(5,6-dimethoxy-2-methylthio-1H-benzo[d]imidazol-1-yl)-1-ethanone (1), 1-(6-ethylthio-5H[1,31dioxolo[4',5':4,5] benzo[d]imidazol-5-yl)-1-propanone (2), 1-(2-ethylthio-6,7-dihydro-1H[1,4]dioxino [2:3':4,5]benzo[d]imidazol-1-yl)-1-pro-panone (3) and 2,3,9,10-tetrahydro-8H [1,4]dioxino[2' 3":4',5']benzo[4,5]imid-azo[2,1-b][1,3]thiazin-10-one (4)) possess strong cardiotonic activity. The goal of this study was to investigate the effect of compounds 1-4 on the action potential (AP) duration and contractile force in guinea pig atrium activated by carbachol and in guinea pig heart papillary muscles. METHODS: The experiments were carried out on the guinea pig papillary muscles and atrium. Isometric contraction and transmembrane potential were recorded using a force transducer and standard microelectrode technique. RESULTS: Compounds 1-4 exerted a positive inotropic effect in a dose-dependent manner on the electrically driven left atrium and papillary muscles, more pronounced in atrium. In response to 1 micromol/L carbachol the AP duration at a 90 % repolarization in atrium shortened more than 70 %, the isometric contraction decreased to the similar level as well. Compounds 1 and 4 significantly antagonized the shortening of the AP duration induced by carbachol and increased it. Compound 1 abolished the reduction of isometric contraction as well. Derivative 3 significantly lengthened (31 ms) the AP duration at a 90 % repolarization in papillary muscles, while 1 and 4 failed to affect this index. The selective blockade of the rapid component of the delayed rectifier potassium current (Ikr) by dl-sotalol (1 micromol/L) did not show the substantial influence on benzimidazole effects. CONCLUSION: These findings support the hypothesis that the tested benzo[d] imidazole derivatives abolish the influence of carbachol on AP and the isometric contraction by inhibition of acetylcholine-activated potassium current (KACh) in guinea pig atrial myocytes and therefore may be beneficial for the prognosis of patients with advanced heart failure and atrial fibrillation.

Action Potentials↗
PubMed1963

Properties of guinea pig 7S antibodies. I. Electrophoretic separation of two types of guinea pig 7S antibodies.

Guinea pigs hyperimmunized with single protein antigens or hapten conjugates emulsified in complete adjuvants produced two types of precipitating antibodies with different electrophoretic mobilities. "Slow" migrating antibody generally appeared earlier and "fast" migrating antibody later in the course of immunization. Animals initially immunized by the intraperitoneal route with hapten conjugates without adjuvants produced primarily fast migrating antibody. Purified guinea pig antibodies were also separable into slow and fast migrating components by electrophoresis in supporting media. Using suitable antisera prepared in rabbits hyperimmunized with guinea pig serum, it was demonstrated that slow and fast antibodies have both common and distinct antigenic determinants. Analytical ultracentrifugation disclosed that both antibodies have sedimentation coefficients of approximately 7S. These antibodies have been designated guinea pig 7Sgamma(1) and 7Sgamma(2).

Animals↗
PubMedDate not supplied

Increased incidence of oviduct pathology in the guinea pig after repeat vaginal inoculation with the chlamydial agent of guinea pig inclusion conjunctivitis.

BACKGROUND AND OBJECTIVES: Although it has been hypothesized that repeated infections with Chlamydia trachomatis result in an increased potential for the development of infertility, it is not know whether repeated chlamydial infection by the vaginal route will result in an increased incidence of upper tract pathology or enhanced pathology. GOAL OF THIS STUDY: To determine whether guinea pigs given two infections with the chlamydial agent of guinea pig inclusion conjunctivitis would experience an increased incidence of pathologic changes compared with animals having only a single infection. STUDY DESIGN: Guinea pigs previously infected with guinea pig inclusion conjunctivitis were challenged with a fresh intravaginal inoculum 73-77 days after the primary infection. Oviducts were examined either nine or 30 to 37 days after the challenge infection for pathologic changes and compared with control unchallenged animals 75 to 85 days after a primary infection. RESULTS: A significant increase in the number of animals with oviducts demonstrating marked tubal dilatation was observed in the challenged animals 30 to 37 days after the challenge infection. There was no association of increased antibody titer and chlamydial Hsp60 with the presence of tubal dilatation. CONCLUSION: These data strongly indicate that repeated infection via the natural vaginal route does increase the risk of tubal damage.

Animals↗
PubMed1992

Bradykinin receptors in the guinea-pig taenia caeci are similar to proposed BK3 receptors in the guinea-pig trachea, and are blocked by HOE 140.

1. Bradykinin (BK) receptors of the guinea-pig taenia caeci were compared with those of the guinea-pig trachea, a preparation proposed to possess novel BK3 receptors. 2. Bradykinin-evoked contractile responses were unaffected in both preparations by the selective BK1 receptor antagonist [des-Arg9,Leu8]-BK (1 microM-10 microM). The BK2 receptor antagonists, D-Arg-[Hyp3,D-Phe7]-BK and D-Arg-[Hyp3,Thi5,8,D-Phe7]-BK, both had low affinities (apparent pKB estimates less than 6) which did not differ significantly between the two preparations (P greater than 0.05). In contrast, the novel bradykinin receptor antagonist D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]-BK (HOE 140) potently antagonized responses to bradykinin with relatively high affinity (apparent pKB = 8.42 +/- 0.15 and 8.94 +/- 0.16 in the taenia caeci, and trachea, respectively). 3. We conclude that the bradykinin receptors in the guinea-pig taenia caeci have similar recognition properties to those present in the guinea-pig trachea, and in this respect the taenia caeci represents a useful preparation for the further study of proposed novel BK3 receptors.

Amino Acid Sequence↗
PubMed2001

Comparative study of Helicobacter pylori infection in guinea pigs and mice - elevation of acute-phase protein C3 in infected guinea pigs.

Eighteen Dunkin-Hartley guinea pigs and 50 NMRI mice were inoculated with Helicobacter pylori and the infection followed by culture, histopathology, antibody response, and plasma levels of the acute-phase proteins albumin, C3, and transferrin for up to 7 weeks. The immune response to H. pylori surface proteins was studied by an enzyme immunoassay (EIA) and Western immunoblot and the plasma levels of albumin, C3, and transferrin were analyzed by single radial immunodiffusion. Guinea pigs had a more severe gastritis and a higher EIA immune response than NMRI mice. Serum C3 levels were elevated in infected guinea pigs after 3 and 7 weeks indicating a systemic inflammatory response and a possible link between H. pylori infection and extragastric manifestations such as vasculitis associated with atherosclerosis. Serum cholesterol levels were analyzed in guinea pigs at 7 weeks and indicated a higher level in H. pylori-infected than in control animals, but this difference was not statistically significant.

Acute-Phase Reaction↗
PubMed1985

Chronic experimental allergic neuritis (EAN) in juvenile guinea pigs: immunological comparison with acute EAN in adult guinea pigs.

In order to approach the mechanism of chronic or relapsing course in human chronic inflammatory demyelinating polyradiculoneuropathy, we established a chronic model of experimental allergic neuritis (EAN) in juvenile guinea pigs, and investigated the underlying cellular immune phenomenon in comparison with acute EAN in adult animals of the same strain. Two-week-old Hartley guinea pigs, sensitized with bovine peripheral nerve homogenate, developed chronic or relapsing EAN, whereas all adult animals developed acute monophasic EAN. Morphological examination of both the chronic and acute forms revealed scattered demyelination and mononuclear cell infiltrates which were essentially restricted to the peripheral nervous system, and indistinguishable from each other. Both the in vitro lymphocyte mitogenic response and in vivo skin testing revealed a significantly lower response to neuritogenic antigens (P2 protein and peripheral nerve myelin) in juvenile chronic EAN than in adult acute EAN throughout their respective courses. In addition, we showed, by means of assessing peripheral blood lymphocyte number and its subpopulations, that normal 2-week-old Hartley guinea pigs have not fully developed immunologically. These observations suggested that there was some immunological incompetence especially in cellular immunity in 2-week-old juvenile guinea pigs and that this might be one possible factor leading to chronic EAN.

Acute Disease↗
PubMed1990

In vitro activity of sparfloxacin (CI-978; AT-4140) for clinical Legionella isolates, pharmacokinetics in guinea pigs, and use to treat guinea pigs with L. pneumophila pneumonia.

The activities of sparfloxacin, ciprofloxacin, and erythromycin for 21 clinical Legionella isolates were determined by agar and broth dilution susceptibility testing and by growth inhibition assays in guinea pig alveolar macrophages (sparfloxacin and ciprofloxacin). All three antimicrobial agents had roughly equivalent activities when buffered charcoal yeast extract agar medium supplemented with 0.1% alpha-ketoglutarate was used as the test medium; the MICs for 90% of strains were 1.0 micrograms/ml for erythromycin and sparfloxacin and 0.5 microgram/ml for ciprofloxacin. Buffered charcoal yeast extract medium supplemented with 0.1% alpha-ketoglutarate inhibited the activities of all the antimicrobial agents tested, as judged by the susceptibility of a control Staphylococcus aureus strain. Broth macrodilution MICs for two L. pneumophila strains in buffered yeast extract supplemented with 0.1% alpha-ketoglutarate were less than or equal to 0.03 microgram/ml for sparfloxacin, 0.06 microgram/ml for ciprofloxacin, and 0.25 microgram/ml for erythromycin; only erythromycin was inhibited by this medium. Ciprofloxacin and sparfloxacin (both 0.25 microgram/ml) reduced bacterial counts of two L. pneumophila strains grown in guinea pig alveolar macrophages by 2 log10 CFU/ml, but regrowth occurred over a 3-day period. Sparfloxacin, but not ciprofloxacin (both 1 microgram/ml), caused a 3- to 4-day postantibiotic effect. Pharmacokinetic and therapy studies of sparfloxacin were performed in guinea pigs with L. pneumophila pneumonia. For the pharmacokinetic study, sparfloxacin was given (10 mg/kg of body weight) to infected guinea pigs by the intraperitoneal route; peak levels in serum and lung were 2.6 micrograms/ml and 1.6 micrograms/g, respectively, at 1 h, with a terminal-phase half-life of elimination from serum of 5 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1962

Influence of guinea pig plasma factors on phagocytosis of Pasteurella pestis. I. Plasma from normal guinea pigs.

Stanziale, W. G. (Fort Detrick, Frederick, Md.) and J. D. White. Influence of guinea pig plasma factors on phagocytosis of Pasteurella pestis. I. Plasma from normal guinea pigs. J. Bacteriol. 83:175-181. 1962.-The existence of an enhancing effect of normal guinea pig plasma on the phagocytosis of Pasteurella pestis has been reaffirmed, using a test system consisting of neutrophils from normal nonimmune guinea pigs as the phagocytes. This enhancing influence was found to be attributable to the interplay of a thermolabile and a thermostable plasma component. The data suggest a consideration of complement as the thermolabile component, since the enhancing activity of plasma is destroyed by heating to 56 C and restored by addition of fresh plasma. The possibility that the thermolabile plasma component is opsonin was discounted. Surface alterations which did occur resulted in preserving the integrity of the envelope substance of the plague bacillus. Treatment of neutrophils with plasma prior to phagocytosis did not increase their phagocytic capacity. The thermostable enhancing component was not demonstrated to be present in any of three purified serum protein fractions tested. In fact, all of these fractions inhibited phagocytosis of P. pestis. An enhancing effect of purified fibrinogen could not be demonstrated.

Animals↗