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At least 19 recordsLinked to original sources
PubMed1978

[Comparative histological studies of mouth mucosa, gingiva and desmodont in normal guinea pigs and guinea pigs fed a vitamin C deficient diet].

The changes occurring in the oral mucosa, gingivae and periodontium of guinea pigs fed a vitamin C-deficient diet were determined by means of histological comparison with animals on a normal diet. The following results were obtained from the scorbutic guinea pigs: --detachment of the horny layer from the underlying epithelium, --bullous cells in the spinose and the granular layer, --formation of periodontal pockets, --reduction in number and disorientation of collagenous fibres of the periodontium associated with loosening of the molars.

Animals↗
PubMedDate not supplied

[Incorporation of 2-14C-acetate into the glycolipids of the spinal cord and brain stem of normal guinea pigs and guinea pigs in the paralytic stage of triorthocresylphosphate poisoning].

Paralytical form of chronic intoxication was caused by single intracutaneous administration of tri-O-cresyl phosphate (TOCP)/2=2.2 ml/kg/ into guinea pigs. Within the first 27--33 days after the treatment, the animals with pronounced symptoms of neurotoxic effect of TOCP were subcutaneously administered with 2-14C-acetate/100 mu Ci per 100 g of body weight/2 hrs before decapitation. Purified cerebrosides, gangliosides and acid-soluble fraction, containing 14C-precursors, were isolated and their specific radiactivity was measured in a gas-flow counter. The rate of 14C incorporation into cerebrosides and gangliosides in spinal cord was found to exceed that in brain stem. In paralytical stage of disease, caused by TOCP, synthesis of cerebroside was depressed in spinal cord and in brain stem, according to calculated value for relative specific radioactivity. In spinal cord the rate of 14C incorporation into gangliosides was also decreased. These data suggest that neurtoxic drug TOCP affects metabolic processes both in oligodendroglial cells and in neurons, where ganglioside biosynthesis occurs.

Acetates↗
PubMed1977

Comparison of endotoxin and leukocytic pyrogen pyrogenicity in newborn guinea pigs.

Guinea pigs under 8 days of age generally are unable to develop fever (viz., deltaTre greater than 0.5 degrees C) in response to a standardized dose of endotoxin (2 mug/kg iv of Salmonella enteritidis [SE]). This study was undertaken to determine whether this lack of responsiveness might be due to an incapacity of leukocytes from young neonates to produce sufficient leukocytic pyrogen (LP). Three series of experiments were performed at Ta = 27 degrees C: guinea pigs aged 0-2, 4, and 8 days were injected iv with: a) 2, 4, 8, or 16 mug/kg of SE, b) 0.1, 0.5, or 1.0 ml of LP generated by 8 mug of SE/25 X 10(6) leukocytes from adult guinea pigs (LPa), or c) 0.1 or 1.0 ml of LP generated by 8 mug of SE/25 X 10(6) leukocytes from 0-5-, 6-12-, and 13-16-day-old guinea pigs (LPn). Adult guinea pigs received iv 1.0 ml of LPa or LPn. The results revealed that fever could be induced in these animals from birth, but the required doses of SE, LPa and LPn were greater the younger the guinea pigs. Under these conditions, LPn, regardless of the donors' ages, produced fever in all the recipients. It is concluded that the pyrogenic unresponsiveness of newborn guinea pigs to endotoxin may be related not to an inability of leukocytes from these neonates to elaborate LP, but rather to an insensitivity of, presumably, their hypothalamic febrogenic mechanisms to low levels of LP.

Age Factors↗
PubMed1977

The effects of cholesterol/fat feeding on lipid levels and morphological structures in liver, kidney and spleen in guinea pigs.

Guinea pigs were fed a semisynthetic diet containing 10 per cent (by weight) cottonseed oil with or without 1 per cent cholesterol. In the animals fed fat, the lipid levels and the morphology remained normal in all tissues studied. Concomitantly with a marked accumulation of cholesteryl ester (CE) in the liver, however, many microscopical changes occurred in guinea pigs fed cholesterol/fat. A prominent deposition of lipids in vacuoles, mostly without delimitating membranes, where observed at centrilobular sites. Multivacuolated, secondary lysosomes, membrane bound lipid vacuoles (lipolysosomes) and myelin figures were found both in hepatocytes and Kupffer cells. Myelin figures and crystalline clefts were observed more often in Kupffer cells than in hepatocytes. The granular endoplasmic reticulum in the Kupffer cells was grossly dilated and filled with an amorphous material. Both the biochemical and the morphological findings in hepatocytes and Kupffer cells are very similar to those observed in cholesteryl ester storage disease and in Wolman's disease. These two lipid storage diseases are both related to deficiency of an acid lipase in the liver. Measurement of the acid liver CE hydrolase in guinea pigs fed fat and in those fed cholesterol/fat showed similar activity. A relative deficiency of this enzyme activity could be the reason for the development of the enormous CE storage in guinea pig livers. These findings suggest that guinea pigs fed cholesterol/fat, in some respects, can be used as a model for Wolman's disease and cholesteryl ester storage disease. We did not find any microscopical changes in the kidneys from animals fed cholesterol/fat, thus indicating that the experimental condition it not useful as a model for studies of the kidney changes in lecithin:cholesterol acyltransferase (LCAT) deficiency.

Animals↗
PubMed1975

Vaccination against bovine brucellosis with a low dose of strain 19 administered by the conjunctival route. I.--Protection demonstrated in guinea pigs.

Guinea pigs were vaccinated with different doses of strain Brucella abortus B 19, subcutaneously (SC) or by the conjunctival route (C), once or a second time three months later. Agglutination and complement fixation titers were determined on sera of guinea pigs taken at random at intervals from each vaccine group. Protection afforded by the vaccination was determined by intramuscular injection of the challenge strain, B. abortus 544 (5 X 10(3) bacteria) three months after the last vaccination. Forty days later the guinea pigs were killed and Brucella looked for and counted in the spleen and lymph nodes. After conjunctival vaccination with 10(6) or 10(7) bacteria, seriological responses were weak and transient even after the re-vaccination, and were lower than after subcutaneous vaccination with the 10(6) dose, and much lower than after the standard vaccination dose of 7 X 10(9) given subcutaneously. Protection, expressed as percentage of guinea pigs free of infection at autopsy (table 4) was 40 p. 100 in the standard vaccination group (SC, 7 X 10(9)) and 57 p. 100 in groups receiving successively 7 X 10(9) (SC) and 10(6) or 10(7) (C). Two successive conjunctival vaccinations with the 10(6) to 10(9) doses gave 47 to 60 p. 100 protection; two SC vaccinations with the 10(6) dose gave 75 p. 100 protection. All the control guinea pigs were heavily infected. The differences in protection rate among the groups vaccinated twice were not significant. Since vaccination through the conjunctiva with two successive instillations of 10(7) bacteria induced only a weak antibody response and protection equivalent to that of standard subcutaneous vaccination, the method appears worthy of application in cattle.

Animals↗
PubMed1979

Cell-mediated cytotoxicity and humoral immune response in ascorbic acid-deficient guinea pigs.

Guinea pigs were divided into three dietary groups: ascorbic-acid deficient, pair-fed, and ad libitum control. Two weeks later guinea pigs were immunized intradermally with 5 x 10(8) chicken erythrocytes in Freund's complete adjuvant. Hemagglutinating antibody titers to chicken erythrocytes 2 weeks after immunization were comparable in all three dietary groups. In vitro 51Cr release from labeled chicken erythrocyte target cells incubated with lymphoid cells from spleens of ascorbic acid-deficient guinea pigs was significantly less than with spleen cells from pair-fed and ad libitum control guinea pigs. The percentage of splenic lymphoid cells that formed rosettes with rabbit erythrocytes, a T cell marker, was the same in all three dietary groups. The defect of ascorbic acid deficiency may reflect an impairment of T lymphocytes function in cell-mediated cytotoxicity or a change in number or function of another cell type.

Animals↗
PubMed1976

In vivo and in virto cellular responses to cytoplasmic and cell wall antigens of Histoplasma capsulatum in artificially immunized or infected guinea pigs.

Guinea pigs were infected with different doses of yeasts of Histoplasma capsulatum or artifically immunized with several concentrations of unextracted yeast cell walls, and then tested in vivo and in vitro for cell-mediated responses to various subcellular fractions of the fungus. Three types of cell-mediated responses were measured, viz., skin test activity, production of migration inhibition factor, and lymphocyte transformation. Positive cutaneous reactions were elicited in animals immunized with 100 or 1,000 mug of cell walls when such animals were skin-tested with cell wall glycoprotein of soluble cytoplasmic substances, whereas animals immunized with 2,000 mug of cell walls did not react significantly greater than unsensitized animals when skin-tested with the same antigens. Histoplasmin did not elicit cutaneous sensitivity in guinea pigs infected with the smallest inoculum, 6 X 10(5) yeast cells, or in animals immunized with cell walls, regardless of the concentration of cell walls used as immunogen. However, hypersensitivity to H. capsulatum could be detected with cytoplasmic substances in animals infected with 6X 10(5). In guinea pigs infected with larger doses, i.e., 10 X 10(7), 15 X10(7), or 20 X 10(7), hypersensitivity could be detected with histoplasmin, cell wall glycoprotein, a ribosome-rich fraction, and soluble cytoplasmic substances. Both cell wall glycoprotein and soluble cytoplasmic substances were functional in migration inhibition factor assays with peritoneal exudate cells from animals immunized with 100 or 1,000 mug of cell walls. The transformation of lymphocytes from infected and artificially immunized guinea pigs in the presence of cell wall glycoprotein and soluble cytoplasmic substances was variable and unpredictable, the lymphocytes from some animls within a given group transforming and those from other animals showing no evidence of stimulation. Moreover, the level of stimulation could not be correlated with the degree of dermal hypersensitivity. These findings suggest that cell wall glycoprotein, and the fractions containing ribosomes and soluble cytoplasmic substances, could be useful antigens in assays for cellular immunity, and warrant further investigation with respect to specificity and active components.

Animals↗
PubMed1978

Biosynthesis of estrogens in pregnant and non-pregnant guinea pigs.

Guinea pig ovaries obtained from pregnant and non-pregnant animals, incubated in the presence of a NADPH-generating system, converted [3H]-dehydroepiandrosterone and [14C]testosterone to estradiol. Under the same conditions, no radioactive estrogen could be identified in adrenal and placental incubations. The rate of formation of estradiol from dehydroepiandrosterone was linear during the 30-min incubation. The initial rates of formation for estradiol were 415 X 10(-13) and 10.4 X 10(-13) mol/min/g tissue for the ovaries from pregnant and non-pregnant guinea pigs, respectively. The formation of estrone was shown only in the pregnant animal, and the initial rate of formation was 36.0 X 10(-13) mol/min/g tissue. These in vitro studies suggest that the major site of estrogen formation in both pregnant and non-pregnant guinea pigs is the ovary.

Animals↗
PubMed1978

Use of enteric vaccines in protection against chlamydial infections of the genital tract and the eye of guinea pigs.

Guinea pigs in a test group were fed living guinea pig inclusion conjunctivitis (GPIC) organisms classified as Chlamydia psittaci in 60% yolk-sac suspensions as enteric vaccines, while animals in a control group received uninfected yolk sac. Seven test animals and 14 control animals were challenged 11 or 22 days later with 1,000 50% infectious doses of GPIC organisms in either the conjunctiva or the vagina. Evidence of protection from mucosal infection in both sites was noted in test animals. Clinically, the disease was less severe, and microbiologically, lower percentages of mucosal cells were infected. The results suggest that enteric vaccination against mucosal infections of the eye and the genital tract with chlamydial agents is possible.

Administration, Oral↗
PubMed1977

Sensitization potentials of methyl, ethyl, and n-butly methacrylates and mutual cross-sensitivity in guinea pigs.

Guinea pigs could be strongly sensitized to methyl, ethyl, and n-butyl methacrylates in ethanol or olive oil by the topical route, or in saline by the intradermal route. For elicitation of skin reactons, topical challenge with the compounds in olive oil or intradermal challenge with saline as the solvent was neccessary. Topical challenge with the methacrylates in ethanol failed to elicit any allergic skin reactions because of their volatility. All sensitized animals responded strongly not only to the inducing methacrylate but also to the other methacrylates, showing that mutual cross-sensitivity had occurred. Since methyl methacrylate has been reported to be a potent sensitizer in humans, the guinea-pig model described here may be useful for screening products before marketing.

Acrylates↗
PubMed1976

Lincomycin-induced cholecystitis and gallstones in guinea pigs.

Guinea pigs given lincomycin 60 mg per kg per day showed a striking increase in the renewal of epithelial cells in the gallbladder. This was detectable after only 24 hr of treatment. By 48 hr a precipitate consisting predominantly of calcium and bilirubin had formed in the gallbladder. Gallbladder bile glycoprotein concentrations rose progressively. At 8 days epithelial dysplasia was marked. Treatment was discontinued at 9 days. The guinea pigs that survived beyond 34 days showed that new tubuloalveolar glands had formed focally in the body and fundus of the gallbladder. Multiple calcium-containing stones were present. The failure to culture bacteria from bile, the failure of the bile salt pattern to change, and the progressive nature of the epithelial injury suggested that the changes resulted from a direct toxic effect and were not dependent on the antibiotic activity of this drug. It was concluded that damage to the epithelium of the gallbladder preceded the formation of a precipitate and initiated histological changes which culminated, at the time that the precipitate became organized into stones, in impressive glandular metaplasia.

Animals↗
PubMed1978

Cholesteryl ester metabolism in fat- and cholesterol/fat-fed guinea pigs.

Guinea pigs were fed a semisynthetic diet containing 10% (by weight) cottonseed oil with or without 1% cholesterol. In response to cholesterol/fat feeding there was a significant accumulation of cholesteryl ester (CE), particularly in the liver, but also in the kidney, spleen and suprarenal glands. The hepatic acyl-CoA:cholesterol acyltransferase (ACAT) increased 5-10 times when the animals were fed cholesterol fat during 11 weeks while the acid cholesterol esterase (CE-ase) was similar in the two dietary groups. Intestinal lymph showed the highest content of cholesterol (both free and esterified) in guinea pigs fed cholesterol/fat. A low activity of lecithin:cholesterol acyltransferase (LCAT) was present in the intestinal lymph, irrespective of dietary composition. Triglyceride-rich lipoproteins seem to inhibit LCAT activity in the intestinal lymph. Plasma cholesterol levels in animals fed cholesterol/fat increased markedly while LCAT remained unaffected by the diets. Activity of ACAT and CE-ase in kidney and spleen was low compared to liver tissue and the enzyme activities were not affected by the cholesterol/fat feeding.

Adrenal Glands↗
PubMed1979

Induction of cell-mediated immunity to Mycobacterium leprae in guinea pigs.

Guinea pigs immunized with intact or disrupted armadillo-grown human Mycobacterium leprae administered in aqueous or oil vehicles were tested with various dilutions of M. leprae suspended in saline, water-soluble M. leprae extract, purified protein derivative, and a water-soluble extract of normal armadillo tissue. The results demonstrated the following. (i) Under no conditions was any skin test reactivity found to normal armadillo tissue extract. (ii) Positive sensitization to both M. leprae and its water-soluble extract was achieved by sensitizing guinea pigs with M. leprae suspended in Hanks solution or saline. Autoclaved M. leprae in Hanks solution or saline inoculated intradermally was an effective immunogen. Oil suspensions or emulsions were effective at sensitization, but appeared to be no better and, in general, slightly weaker, than simple inoculation in aqueous suspension. (iii) Living BCG failed to reveal a significant adjuvant effect on sensitization to M. leprae. However, cord factor appeared to potentiate slightly the sensitization to M. leprae in aqueous suspension. (iv) The minimum dose required for sensitization with M. leprae in aqueous suspension was 55 micrograms of purified bacilli. (v) Animals inoculated with M. leprae in saline or with M. leprae together with BCG showed positive skin test reactivity to the first skin test application made fully 1 year after the initial sensitization. The efficacy of autoclaved, irradiated M. leprae in aqueous, oil-free medium suggests a relatively safe approach to human vaccination studies.

Adjuvants, Immunologic↗
PubMed1979

Influence of cholesterol/fat feeding on cholesterol esterification and morphological structures in intestinal mucosa from guinea pigs.

Guinea pigs were fed a semisynthetic diet containing 10% (by weight) cottonseed oil and 1% cholesterol. In response to cholesterol/fat feeding there was an increase in both the unesterified cholesterol (UC) and cholesteryl ester (CE) of the intestinal mucosal cell. Along with the increased cholesterol levels there was a 4-fold increase in the microsomal acylCoA:cholesterol acyltransferase (ACAT) activity after only two days of cholesterol/fat feeding. After 6 days on the experimental diet the ACAT activity was up to 8-fold the activity of the control, and then remained at this level for up to 20 days. The increased ACAT activity was probably not due to increased substrate concentration alone, since the fractional esterification of cholesterol also increased when the cholesterol/fat containing diet was given. There was also an increase in the triglyceride content of the intestinal mucosal cells from guinea pigs on the experimental diet. The mucosal cells of the cholesterol/fat fed animals accumulated varying amounts of lipid droplets, which were without an enveloping membrane, suggesting that the uptake of lipids from the intestinal lumen was higher than the capacity to synthesize and/or secrete lipoproteins. Simultaneously the size and amount of secondary lysosomes increased. A considerable increase in lipid droplets, lipolysosomes, and residual bodies was observed in the lamina propria macrophages while no crystalline clefts were seen.

Animals↗
PubMed1976

Comparison of guinea pig cytomegalovirus and guinea pig herpes-like virus: growth characteristics and antigentic relationship.

The growth characteristics of guinea pig cytomegalovirus (GPCMV) and guinea pig herpes-like virus (GPHLV) in cell cultures were compared. Guinea pig fibroblast cells were highly susceptible to infection with both viruses, whereas guinea pig kidney cells were sensitive only to GPHLV. No cytopathic effect was observed in the latter cell system after infection with GPCMV,nor was there an increase in virus titer, although the cirus persisted in the kidney cells for 2 to 3 weeks postinfection. Electron microscope studies showed nonvirion tubular structures in GPCMV -infected fibroblast cells, but not in GPHLV- infected cells. Large packages of enveloped nuclear virus particles were commonly seen in GPHLV -infected cells, especially kidney epithelial cells, but none were found in the GPCMV -infected fibroblasts. Complete enveloped extracellular virus particles were present in both virus-cell systems. Both viruses showed narrow host spectra and replicated well only in guinea pig cells although GPHLV multiplied to some degree in rabbit cells. No antigenic relationship could be demonstrated between the two viruses using antisera specific for each virus that was produced in rabbits and guinea pigs. Rabbits produced high neutralizing antibody titers to GPHLV, whereas guinea pigs were the animals of choice for GPCMV antiserum production.

Animals↗
PubMed1976

Comparison of guinea pig cytomegalovirus and guinea pig herpes-like virus: pathogenesis and persistence in experimentally infected animals.

The pathogenesis of guinea pig cytomegalovirus (GPCMV) and guinea pig herpes-like virus (GPHLV) in guinea pigs was compared. Animals were inoculated with the two viruses by different routes and sacrificed after varying periods of time. GPCMV was consistently isolated from salivary gland 2 weeks postinoculation and thereafter following intraperitoneal or subcutaneous incoulaton. Virus was less frequently found in other tissues including blood, spleen, and kidney. Intranuclear inclusions were seen in tissue sections of salivary gland after inoculation with GPCMV- infected tissue suspension, but were only rarely found after inoculation with tissue culture virus. In GPHLV-infected guinea pigs, consistent latent infection of leukocytes and other tissues was detected by cocultivation techniques. Intranuclear inclusions were not found in the spleen, salivary gland, or other infected tissues after GPHLV infection with either tissue culture virus or infected tissue suspension. Guinea pigs inoculated with GPCMV produced high titers of specific neutralizing antibody to the homologous virus; those inoculated with GPHLV developed long-term viremia accompanied by minimal neutralizing antibody levels to the virus.

Animals↗
PubMed1976

Formed blood elements in peritoneal effusion and the macrophage migration inhibition test in healthy guinea pigs and in guinea pigs with experimental allergic encephalomyelitis.

An attempt was made to correlate the percentages of macrophages, lymphocytes and granulocytes in the peritoneal effusion in healthy guinea pigs and guinea pigs with experimental allergic encephalomyelitis (EAE), with the macrophage migration inhibition (MMI) test. Varying percentages of the cells had no influence on values of MMI. Similarly, in guinea pigs with EAE, percentages of formed elements in peritoneal effusion were not correlated with intensity of MMI or with histopathologic lesions in the brain and spinal cord. It is suggested that the observed differences are due to individual immunologic responsiveness of animals and, probably, to other hitherto unknown mechanisms.

Animals↗
PubMed1976

Effect of chronic exposure to nitrogen dioxide on collagen fractions content in skin of guinea pigs.

Guinea pigs were exposed to nitrogen dioxide in concentration of 2 mg/m3 (8 hrs. daily, 180 days). Control group inspired fresh air. Collagen fractions were estimated in skin and assayed as hydroxyproline concentration. An increase of total collagen content, due to on increase of salt-soluble collagen fraction was found in the skin of the exposed animals, while a simultaneous decrease of insoluble collagen content was observed.

Animals↗