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Leptospirosis is a disease of worldwide distribution that affects man and several animal species. Domestic and wild animals can behave as reservoirs of the agent. The aim of this study was to evaluate the frequency of anti-Leptospira spp. antibodies in dogs and wild small mammals from rural properties and conservation units of three municipalities of Rio Grande do Sul State, Brazil. Sera were collected from 192 domestic dogs and 132 small mammals, namely rodents of the Cricetidae and Caviidae families and marsupials of the Didelphidae family. The study used Microscopic Agglutination Test (MAT) against 23 serovars of Leptospira spp. Overall, 9.90% (19/192) dogs, and 1.51% (2/132) small mammals were seropositive. Leptospira interrogans serovar Australis was the most frequent serovar in dogs and antibodies against L. interrogans serovar Pomona were detected in a dog and a small mammal belonging to the same municipality. We conclude that in the regions studied the frequency of seropositivity in dogs is low, and leptospires do not seem to be circulating in small mammals, yet, further research is necessary to assess the real role that these animals may have for leptospirosis in the studied areas. This is the first serological survey in small mammals, including wild rodents, in the area that encompasses conservation units of great importance to Rio Grande do Sul state. Keywords: Dogs, Small mammals, Leptospirosis, Rio Grande do Sul

Cardiovascular disease (CVD) is the leading cause of death among women worldwide, and risk for developing CVD increases postmenopause. Consumption of trans-fatty acids (tFA) has been positively associated with CVD incidence and mortality. The current study was designed to assess the effects of diets high in industrially produced (IP)-tFA, from partially hydrogenated vegetable oils (PHVO), and ruminant-produced (RP)-tFA, from butter oil (BO), on risk factors for CVD. Thirty-two female Hartley guinea pigs, one-half of which were ovariectomized (OVX) to mimic the postmenopausal condition, were fed hypercholesterolemic diets containing 9% by weight PHVO or BO (n = 8/diet and ovariectomy) for 8 wk. The plasma and hepatic lipids did not differ between IP- and RP-tFA groups or between intact and OVX guinea pigs. The BO diet resulted in higher concentrations of plasma total and small HDL particle subclass concentrations than the PHVO diet regardless of ovariectomy status. The intact BO group had higher concentrations of large HDL particles than the intact PHVO group. HDL mean particle size tended to be larger (P = 0.07) in the PHVO groups compared with the BO groups regardless of ovariectomy status. There was a trend toward an interaction between diet and ovariectomy status for LDL mean particle size, which tended to be larger in OVX guinea pigs fed PHVO (P = 0.07). In summary, consumption of IP- and RP-tFA resulted in differential effects on HDL particle subclass profiles in female guinea pigs. The effect of tFA consumption and hormonal status on HDL particle subclass metabolism and the subsequent impact on CVD in females warrants further investigation.

Although trans-fatty acid (tFA) intake has been positively associated with coronary heart disease (CHD), the relative effect of consuming industrially produced (IP)- compared with ruminant-produced (RP)-tFA on CHD risk factors is unclear. This study was designed to examine the effects of feeding partially hydrogenated vegetable oil (PHVO), IP-tFA source, and butter oil (BO), RP-tFA source, on the development of atherosclerosis and risk factors associated with CHD. Forty-eight male Hartley guinea pigs were fed a hypercholesterolemic diet containing (9% by weight) PHVO, BO, coconut oil (CO; positive control), or soybean oil (SO; negative control) for 8 or 12 wk (n = 6/group). Morphological analysis revealed that none of the groups developed atherosclerosis. Plasma and hepatic lipids did not differ between the tFA groups, but total and small HDL particles were significantly higher in the BO group than in the PHVO group and mean HDL particle size was significantly smaller in the BO group than in the PHVO group. Compared with the other treatment groups, the SO treatment resulted in significantly lower total cholesterol (TC) and LDL cholesterol in plasma, whereas hepatic TC was significantly higher in the SO group than in the other treatment groups. Plasma and hepatic cholesterol concentrations did not differ between the tFA and CO treatments. These results demonstrate that when fed at a high dose, IP- and RP-tFA had the same effect on established CHD risk factors in male Hartley guinea pigs. The effects of RP-tFA on HDL particle sizes and concentrations warrant further investigation.

It is well established that the nutritional status of the host affects resistance to disease. The impact of dietary lipids on experimental pulmonary infection with mycobacteria has not been investigated. Therefore, the purpose of this study was to determine the role of dietary (n-3) and (n-6) fatty acids on immunity and resistance to aerosol infection with virulent Mycobacterium tuberculosis in guinea pigs. Weanling guinea pigs were fed purified, isocaloric diets differing only in lipid source, and the effects of diet on specific immune cell functions were evaluated after 3 or 6 wk. Dietary (n-3) fatty acid consumption reduced in vivo skin test and in vitro lympho-proliferative responses (P < 0.05) relative to (n-6) fatty acid consumption. The effect of diet on resistance to mycobacterial infection was assessed by enumerating viable mycobacteria in the lungs and spleens of guinea pigs infected with virulent M. tuberculosis by the aerosol route. (n-3) Fatty acid-fed guinea pigs had more bacteria in the lungs compared with (n-6) fatty acid-fed guinea pigs at 3 (P < 0.05) and 6 wk postinfection (P < 0.01). These data document the immunomodulatory effects of (n-3) fatty acid consumption in the context of tuberculosis resistance. The loss of antigen-specific T-cell functions in addition to impaired resistance to mycobacterial disease suggests a susceptible phenotype in (n-3) fatty acid-fed guinea pigs.

Insufficient ascorbate intake causes scurvy in certain species. Beyond its known functions, it has been suggested that ascorbate participates in oxidative protein folding in the endoplasmic reticulum (ER). Because redox imbalance in this organelle might cause ER stress and apoptosis, we hypothesized that this might contribute to the pathology of scurvy. Guinea pigs were divided into 7 groups: the control group was fed a commercial guinea pig food containing 0.1 g/100 g ascorbate for 4 wk, 5 groups consumed an ascorbate-free food for 0, 1, 2, 3, or 4 wk and 1 group was fed this scorbutic diet for 2 wk and then the commercial food plus 1 g/L ascorbate in drinking water for 2 wk. TBARS generation and the expression of some ER chaperones and foldases were determined in hepatic microsomes. The apoptotic index was assessed in histological sections. Although ascorbate, measured by HPLC, was undetectable in the livers of the guinea pigs after they had consumed the scorbutic diet for 2 wk, the microsomal TBARS level was elevated relative to the initial value only at wk 4. Western blot revealed the induction of GRP78, GRP94, and protein disulfide isomerase at wk 3 and 4. Apoptosis was greater than in the control, beginning at wk 3. None of the alterations occurred in the groups fed the commercial guinea pig food or ascorbate-free food followed by ascorbate supplementation. Therefore, persistent ascorbate deficiency leads to ER stress, unfolded protein response, and apoptosis in the liver, suggesting that insufficient protein processing participates in the pathology of scurvy.

Preventing anaphylactic reactions as a result of natural rubber latex (NRL) proteins is an important concern in anaesthesia. The clinical relevance of a bacterial/viral filter (Pall BB25) in preventing sensitization to NRL by inhalation was tested in guinea pigs.Guinea pigs (n=8-10 in each group) were exposed to aerosolized NRL-contaminated cornstarch powder or to NRL in saline for 1 h every day for 2 weeks. The experiments were repeated with a Pall BB25 filter placed over the aerosol system. Control groups were exposed to non-contaminated cornstarch or to saline alone. Three weeks after the last exposure, specific bronchial challenge was performed and thromboxane (Tx) B2 levels in bronchoalveolar lavage fluid were measured.After bronchial challenge, the animals exposed to NRL or NRL-contaminated cornstarch with the BB25 filter in place showed a level of bronchoconstriction (i.e. the variation of pulmonary insufflation pressure) not different from controls. Conversely, those exposed to NRL or NRL-contaminated cornstarch without the filter showed a higher level of bronchoconstriction (respectively, P0.02 and P0.001) than control. Elevated TxB2 levels were found in the lungs of the guinea pigs, which inhaled NRL or NRL-contaminated cornstarch in the absence of a filter. Animals treated with the filter showed comparable TxB2 levels with those of control.The Pall BB25 filter efficiently protected the guinea pigs from sensitization to NRL. This filter can be used as a complementary measure for avoidance of NRL contact during surgical procedures particularly if the mechanical ventilator apparatus contain NRL devices.

Female ovariectomized guinea pigs, a model for menopausal women, were fed either a control diet or a diet containing 10 g/100 g of a lyophilized grape preparation for 12 wk. The macronutrient composition of the grape preparation was: simple carbohydrates, 90 g/100 g; protein, 4 g/100 g; and dietary fiber, 6 g/100 g. Control and grape diets had the same composition except for the percentage of macronutrients provided by the grape preparation. Polyphenols were present in the grape preparation at 0.58 g/100 g and included flavans, anthocyanins, quercetin, myricetin, kaempferol and resveratrol. Dietary cholesterol was 0.33 g/100 g to raise plasma cholesterol concentrations and ensure the development of atherosclerosis. Plasma LDL cholesterol concentrations did not differ between groups, whereas plasma triglycerides and VLDL cholesterol were 39 and 50% lower, respectively in guinea pigs fed the grape diet compared with controls (P < 0.05). Significant modifications in LDL particles included 58 and 30% lower triglycerides and phospholipids, respectively (P < 0.0001). Hepatic acyl CoA:cholesteryl acyltransferase activity was 27% lower (P < 0.05) in the grape diet-fed group compared with controls. In addition, concentrations of cholesterol in the aorta were 33% lower (P < 0.05) in guinea pigs fed the grape diet. These results suggest that grape intake in ovariectomized guinea pigs alters hepatic cholesterol metabolism, which may affect VLDL secretion rates and result in less accumulation of cholesterol in the aorta.

Osteoarthritis (OA), one of the most common diseases among the elderly, is characterized by the progressive destruction of joint tissues. Its etiology is largely unclear and no effective disease-modifying treatment is currently available. Metabolic fingerprinting provides a novel tool for the identification of biomarkers. A metabolic fingerprint consists of a typical combination of metabolites in a biological fluid and is identified by a combination of (1)H NMR spectroscopy and multivariate data analysis (MVDA). The current feasibility study was aimed at identifying a metabolic fingerprint for OA and applying this in a nutritional intervention study. Urine samples were collected from osteoarthritic male Hartley guinea pigs (n = 44) at 10 and 12 mo of age, treated from 4 mo onward with variable vitamin C doses (2.5-3, 30 and 150 mg/d) and from healthy male Strain 13 guinea pigs (n = 8) at 12 mo of age, treated with 30 mg vitamin C/d. NMR measurements were performed on all urine samples. Subsequently, MVDA was carried out on the data obtained using NMR. An NMR fingerprint was identified that reflected the osteoarthritic changes in guinea pigs. The metabolites that comprised the fingerprint indicate that energy and purine metabolism are of major importance in OA. Metabolic fingerprinting also allowed detection of differences in OA-specific metabolites induced by different dietary vitamin C intakes. This study demonstrates the feasibility of metabolic fingerprinting to identify disease-specific profiles of urinary metabolites. NMR fingerprinting is a promising means of identifying new disease markers and of gaining fresh insights into the pathophysiology of disease.

Background On the basis of in vitro studies, the antioxidant nutrients vitamins E and C are postulated to interact in vivo. Objective We developed a guinea pig model to evaluate the combined deficiency of vitamins E and C in vivo. Design Weanling guinea pigs were fed a control diet or a vitamin E-deficient diet for 14 d, after which one-half of each group had vitamin C removed from their diet, thus creating 4 diet groups. Some animals were observed for clinical signs. Others were killed for evaluation. Results Of 21 guinea pigs that were observed after being fed the diet deficient in both vitamins, 8 died 9 +/- 2 d (x +/- SD) after starting the diet. Eight additional guinea pigs developed a characteristic syndrome at 11 +/- 3 d. First, they became paralyzed in the hind limbs. Within a few hours, the paralysis progressed to include all 4 limbs and caused difficulty in breathing, which would have caused death had the animals not been euthanized. Histopathologic evaluation did not identify a lesion in the muscles or nervous system that could account for the paralysis. Biochemical measurements confirmed the deficiencies and indicated that the double deficiency caused lipid peroxidation in the central nervous system. Conclusions A distinct clinical syndrome of combined vitamin E and vitamin C deficiency occurs in guinea pigs. This syndrome indicates that these antioxidant vitamins are related in vivo. We speculate that acute oxidative injury in the central nervous system underlies the clinical syndrome.

Study objective: To evaluate the effect of CP-471,474 (Pfizer Global Research and Development; Groton, CT), a broad-spectrum inhibitor of matrix metalloproteinases (MMPs) in an experimental model of emphysema. Design: Randomized, double-blinded, controlled experiment. Setting: Biochemistry and morphology laboratories and animal research facility. Methods: Guinea pigs were exposed to cigarette smoke over 1 month, 2 months, and 4 months, and half of the animals received CP-471,474. Age-matched guinea pigs exposed to room air were used as control animals. After death, the lungs were lavaged with saline solution, and MMPs in the lavage fluid were determined by zymography and immunoblot. Lungs were fixed for histology, immunohistochemistry, and morphometry. Results: Following a 1-month exposure to tobacco smoke, semiquantitative histologic assessment showed moderate lung inflammation, which progressed in extent and severity and reached a peak at 2 months. CP-471,474 significantly reduced both the extent (p < 0.002) and severity (p < 0.05) of inflammation at 2 months. At 4 months, a spontaneous reduction of the inflammatory response was observed in both treated and untreated animals, and consequently no difference was observed between both. Emphysematous changes, revealed by a significant increase in the average size of alveoli, were detected at 2 months and 4 months of tobacco smoke exposure. The inhibitor significantly decreased the destructive lesions mainly at 2 months (p < 0.0001) and also at 4 months (p < 0.02). Smoking increased MMP-9 and MMP-1 activities as shown by zymography and immunoblot. Immunoreactive MMP-9 was mainly localized in alveolar and bronchiolar epithelial cells, macrophages, and airways smooth-muscle cells. Conclusion: These findings support a role for MMPs in the early inflammatory response and in the emphysematous lesions provoked by cigarette smoking. (CHEST 2003; 123:1633–1641)

To evaluate some of the mechanisms involved in the hypocholesterolemic effects of corn fiber oil (CFO), male Hartley guinea pigs were fed diets containing increasing doses of CFO [0 (control), 5, 10 or 15 g/100 g]. Total fat was adjusted to 15 g/100 g in all diets with regular corn oil. Diets contained 0.25 g/100 g cholesterol. A positive control group (LC) with low dietary cholesterol (0.04 g/100 g) was also included. Plasma LDL cholesterol concentrations were 32, 55 and 57% (P < 0.0005) lower with increasing doses of CFO. Compared with controls, intake of CFO resulted in 27-32% lower hepatic microsomal cholesterol (P < 0.0001), the regulatory pool of LDL receptor (LDL-R) expression. CFO intake resulted in favorable plasma and hepatic cholesterol concentrations, similar to those in guinea pigs fed the LC diet. Hepatic cholesterol 7alpha-hydroxylase (CYP7) activity was approximately 88% higher in guinea pigs fed the two higher dosages of CFO (P < 0.05). In parallel, CYP7 mRNA abundance was approximately 88% higher in guinea pigs fed all three CFO diets. CFO treatment also induced hepatic LDLR mRNA by 66-150% with significant differences at the highest CFO dose. These results suggest that CFO, as a result of decreased bile acid absorption, increased mRNA abundance and activity of CYP7. Because hepatic cholesterol is the substrate for CYP7, a lowering of cholesterol concentrations in the total and microsomal pools was observed. As a response to the depleted microsomal free cholesterol pool, the LDL receptor was up-regulated, drawing more cholesterol from plasma, thus leading to the observed decrease in plasma LDL cholesterol concentrations.

This paper provides the first report of spatial learning in guinea pigs using the Morris water maze (MWM). Male and female guinea pigs were trained for 5 consecutive days (8 trials/day; acquisition phase) in either the visible (cued) or the hidden (non-cued) platform version of the MWM. In both tests, guinea pigs learned to navigate to the escape platform, as indicated by a decrease in escape latency over the 5 training days. There were no sex differences in either test version. A comparison of guinea pigs and male Wistar rats showed that performance during acquisition training was not different for the two species in the visible platform test, but rats performed better during the early training days in the hidden platform test. A retention test (probe trial) was given 5 days after the last acquisition training day. Again, there was no sex difference, and no difference between guinea pigs and rats. Finally, acquisition of a new escape response to a shifted platform location was equivalent for rats and guinea pigs of both sexes. These results demonstrate that guinea pigs show robust cued and non-cued learning in the MWM. Both acquisition and retention performance in guinea pigs is similar to that in rats, even though rats appear to have a slight advantage in the acquisition of non-cued, spatial information in this test. We conclude that the MWM provides a valuable paradigm to assess behavior and learning/memory in the guinea pig.

Ascorbic acid is preferentially concentrated in the hypothalamus, pituitary and adrenal glands. Its level in the acini of salivary glands is relatively high. We therefore hypothesized that ascorbate may have a role in salivary gland function. Ascorbate-deficient guinea pigs had lower stimulated whole salivary flow rates than well-fed, age-matched controls (P: < 0.005). Total salivary protein concentration was also markedly (P: < 0.005) reduced in the deficient guinea pigs. SDS-PAGE and densitometric quantification of protein bands confirmed significant reduction in specific salivary proteins (e.g., amylase, proline-rich proteins) in the saliva samples of malnourished guinea pigs. Some protein bands not seen in control saliva were detected in the saliva of malnourished guinea pigs. Ascorbate deficiency also produced a significant (P: < 0.005) reduction in the ss-adrenergic receptor density (subtype 1; 95 +/- 19 fmol/mg protein compared with 179 +/- 27 fmol/mg protein for the controls). No significant difference was observed between the two groups with respect to the ss-adrenergic receptor subtype 2. Additionally, ascorbate-deficient guinea pigs had significantly lower muscarinic-cholinergic receptor densities (50 +/- 5 vs. 74 +/- 8 fmol/mg protein for controls). Our data support the conclusion that diminished membrane receptors might impair the capacity of the transmembrane signaling system, resulting in salivary gland hypofunction in ascorbate-deficient guinea pigs. Without implying extrapolation of our findings in experimental animals to humans, it is perhaps relevant that many conditions often associated with salivary gland hypofunction in humans (e.g., smoking or drug ingestion) deplete cellular ascorbate.

The objective of this study was to assess the effects of gender on the secondary mechanisms by which dietary soluble fiber lowers plasma LDL cholesterol. For that purpose, male, female and ovariectomized (to mimic menopause) guinea pigs (8-10 per group) were allocated to two dietary treatments. Diets were identical in composition except for the fiber source: the control diet contained 10 g/100 of cellulose and 2.5 g/100 g of guar gum, while the soluble fiber (SF) diet contained 5 g/100 of psyllium, 5 g/100 of pectin and 2.5 g/100 g of guar gum. SF intake resulted in 44% lower plasma LDL cholesterol, 64% lower apo B and 22% lower plasma triacylglycerol (TAG) concentrations (P < 0.01) compared to guinea pigs fed the control diet. However, ovariectomized guinea pigs had higher plasma cholesterol, apo B and TAG concentrations (P < 0.01) compared to males and females, even those fed SF. Plasma HDL-cholesterol was higher in females than in males (P < 0.05). LDL size, as measured by LDL composition and fast protein liquid chromatography, was larger in females than males. Guinea pigs fed SF had smaller LDL than controls. LDL susceptibility to oxidation was 80% lower in male and females fed the SF diet (P < 0.001) than in controls, while there was no effect of diet in ovariectomized guinea pigs. Hepatic free cholesterol and TAG were lower, and activities of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase and cholesterol 7α-hydroxylase were higher in guinea pigs fed SF (P < 0.05) than in controls. These results indicate that gender plays an important role in the metabolic responses to dietary soluble fiber and that estrogen deprivation leads to a detrimental lipoprotein profile.

The seasonality of immature stages of Amblyomma tigrinum was studied in an area of theChaco phytogeographical province in Co´ rdoba, Argentina by monthly collection of larvaefrom ground feeding birds and Sigmodontinae rodents, and nymphs from Caviidae rodentsfrom May 2005 to April 2007. An apparent peak of abundance was found from December toMay but differences with other months of the year were not significant (P > 0.05). Theseand previous results suggest that the parasitic stages of A. trigrinum are active throughoutthe year and has more than one generation per year at the study site. Its life cycle appearsto be regulated by temperature with no occurrence of diapause. Fil: Nava, Santiago. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Agencia de Extension Rural Rafaela.; Argentina Fil: Mangold, Atilio Jose. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Agencia de Extension Rural Rafaela.; Argentina Fil: Guglielmone, Alberto Alejandro. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela. Agencia de Extension Rural Rafaela.; Argentina

The effects of anaesthesia on upper airway reflexes in older animals have not been elucidated fully. We studied young (4-month-old) and old (28-month-old) guinea-pigs to examine the relationship between aspiration and altered upper airway reflexes during anaesthesia. We administered an adenovirus vector carrying Escherichia coli LacZ gene (Ad vector) intranasally to guinea-pigs with or without anaesthesia. LacZ gene expression was investigated in the nostrils and lungs of each animal under anaesthesia. No LacZ gene expression was found in the lungs of unanaesthetized animals given Ad vector. Thus intranasal administration of Ad vector was aspirated into the lower airways under anaesthesia. Next we examined the effect of age on anaesthesia-induced aspiration. At a lower concentration of halothane in 100% oxygen, greater LacZ gene expression in the lungs was measured in older than in younger animals, suggesting that older animals are liable to aspirate oropharyngeal contents into the lower airways during light anaesthesia. This novel animal model of aspiration using Ad vector may be useful to explore the mechanism of aspiration during and after anaesthesia in young and old animals.

This experiment was designed to evaluate the effects of pectin (PE), guar gum (GG) and psyllium (PSY) intake on VLDL and LDL metabolism in female guinea pigs fed high dietary cholesterol. Guinea pigs were fed a 15 g/100 g fat diet containing 0.25 g/100 g cholesterol with 12.5 g/100 g PE, 12.5 g/100 g GG, 7.5 g/100 g PSY or 12.5 g/100 g cellulose (control diet) for 4 wk. Plasma cholesterol concentrations were 29, 43 and 39% lower in guinea pigs fed PE, GG or PSY, respectively, compared with the control group (P < 0.0001). Plasma apolipoprotein (apo) B concentrations were 16-22% lower in the groups fed soluble fiber compared with the control group (P < 0.01). In contrast, hepatic cholesterol and triglyceride concentrations were not different among the PE, GG, PSY and control groups. No differences in triacylglycerol (TAG) or apo B secretion rates, measured by blocking VLDL catabolism by triton (WR 1339) injection, were observed, whereas plasma LDL apo B fractional catabolic rates (FCR), determined by injection of radiolabeled LDL, were higher in guinea pigs fed GG or PSY than in those from the control group. All sources of dietary soluble fiber reduced LDL apo B flux (P < 0.05). These results suggest that the mechanisms of plasma LDL cholesterol lowering by dietary soluble fiber are distinctive for each fiber source and result in specific alterations in lipoprotein metabolism in female guinea pigs. Differences between male and female guinea pigs in response to these diets are discussed.

Optimization and Validation of an ELISA to Measure Specific Guinea Pig IgG1 Antibody as an Alternative to the in Vivo Passive Cutaneous Anaphylaxis Assay. Kawabata, T. T., Babcock, L. S., Gauggel, D. L., Asquith, T. N., Fletcher, E. R., Horn, P. A., Ratajczak, H. V., and Graziano, F. M. (1995). Fundam. Appl. Toxicol. 24, 238-246. Assessment of the allergenic potency of enzymes involves the use of a guinea pig model in which specific IgG1 antibody titers are used as the endpoint. The in vivo passive cutaneous anaphylaxis (PCA) assay is used to measure specific IgG1 antibody. This report describes the development and validation of an enzyme-linked immunosorbent assay (ELISA) to measure guinea pig specific IgG1 antibody as an in vitro alternative to the PCA assay. Cross reactivity of various rabbit and mouse (monoclonal) anti-guinea pig IgG1 preparations were evaluated using purified IgG1 and IgG2 from serum of guinea pigs immunized with ovalbumin. The two subclasses of guinea pig IgG were purified by first using Protein A affinity chromatography, followed by anion exchange chromatography and fluid phase isoelectric focusing. Affinity-purified rabbit anti-guinea pig IgG1 was shown to have minimal cross reactivity toward IgG2, while providing a strong signal with IgG1. The ELISA was designed as an antigen capture system in which the following are added in sequence: (1) enzyme antigen (passively adsorbed to the plate), (2) diluted serum samples from guinea pigs immunized with enzyme, (3) affinity-purified rabbit anti-guinea pig IgG1, (4) alkaline phosphatase-conjugated donkey anti-rabbit IgG, and (5) p -nitrophenyl phosphate substrate. Three replicate ELISA and PCA analyses were conducted on sera samples of varying titers from guinea pigs immunized with either Alcalase (protease), BPN' (protease), and Termamyl (amylase) enzyme. The correlation coefficients ( r 2 ) between the ELISA and PCA assay for Alcalase, BPN', and Termamyl were 0.826, 0.945, and 0.755, respectively. These findings demonstrate that the specific antibody ELISA developed in this study is a valid in vitro alternative to the PCA assay to measure anti-enzyme guinea pig IgG1.

Two dye mixtures and the individual component dyes were evaluated for the potential to induce contact or pulmonary hypersensitivity. These dye mixtures were suspect because of anecdotal reports of both pulmonary and contact hypersensitivity in assembly workers, and because the component dyes were structurally related to dyes known to be contact sensitizers. One mixture consisted of disperse blue 3 (DB3) and disperse red 11 (DR11), which are anthraquinones, and the other mixture contained DR11 and solvent red 1 (SR1), an azo dye. Contact hypersensitivity was examined using the local lymph node assay (LLNA) and a modified mouse ear swelling test (MEST). Both the MEST and the LLNA indicated that SR1 has weak contact-sensitizing potential. None of the other individual dye compounds or the two mixtures were identified as contact sensitizers by either method. To evaluate the mixtures as potential pulmonary allergens, guinea pigs were repeatedly exposed by inhalation (300 mg/m3, 6 hr/day) 5 days/week, for 1 week. Weekly exposures were repeated three times with 2 weeks of nonexposure time in between. Guinea pigs were then challenged through the jugular vein using a dye-dimethylsulfoxide mixture. During the challenge, breathing mechanics (dynamic compliance and resistance) were measured in mechanically ventilated animals. Changes in these measurements, indicative of bronchoconstriction, were not observed in animals exposed to either dye mixture, nor were antibodies detected in the sera of exposed animals using individual dye-specific enzyme-linked immunosorbent assays. In conclusion, two methods indicate that SR1 may have contact-sensitizing potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of Benzanthrone Toxicity by Ascorbic Acid in Guinea Pigs. Das, M., Garg, K., Singh, G. B., and Khanna, S. K. (1994). Fundam. Appl. Toxicol. 22, 447-456. Oral administration of benzanthrone (BA) (50 mg/kg body wt/day) to guinea pigs for 30 days resulted in depletion of ascorbic acid (ASA) in the liver, adrenals, and blood serum and in growth retardation (36%) and an increase (18%) in relative liver weight when compared to controls. BA treatment showed a tendency toward normocytic anemia with a decrease in hemoglobin content, reduction in RBC counts, and lowered packed cell volume. Guinea pigs treated with BA showed histopathological changes in liver including fibrosis, bile duct proliferation, and focal necrosis. Testes showed marked damage of seminiferous tubules with vacuolar degeneration and irregular and distorted interstitial spaces. BA showed evidence of patchy glomerular congestion, tubular lesions, and damaged epithelial cells in kidney, while urinary bladders had mild congestion in lamina propia and submucosa. Hepatic GOT, GPT, and LDH were found to be significantly decreased (17.5-33.5%), whereas activities of these enzymes showed a significant elevation in serum of BA-exposed guinea pigs. BA treatment also led to significant decrease of testicular hyaluronidase (29.8%) and LDH (19.8%) and significant depletion of lactic acid content (14.7%). Prior daily oral supplementation with ASA (50 mg/kg body wt) to BA-administered guinea pigs resulted in marked improvement of histopathological and biochemical changes observed in liver, testis, kidney, and urinary bladder of BA-exposed animals. These results suggest that extra supplementation of ASA could attenuate the toxic manifestations of BA.

Guinea pigs were fed increasing concentrations of citrus pectin (CP) (0-12.5%, wt/wt) with low (LC, 0.04%) or high (HC, 0.25%) cholesterol. Animals fed LC diets had reduced plasma LDL concentrations with 10% and 12.5% CP and hepatic membrane apolipoprotein B/E receptor expression increased with high dosages of CP. Hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity increased with 12.5% CP whereas hepatic cholesterol concentrations and acyl-CoA:cholesterol acyltransferase (ACAT) activity were not different. In contrast, with HC diets, plasma LDL concentrations were reduced in a dose-response manner by 29%, 30%, and 67% with 7.5%, 10%, and 12.5% CP intake (P < 0.001) and apolipoprotein B/E receptor number was increased and inversely correlated with plasma LDL in the HC group (r = -0.81, P < 0.005). Animals fed HC diets had a dose-dependent decrease in hepatic cholesterol and ACAT activity, with intake of 12.5% CP having the major effect. Hepatic HMG-CoA reductase activity was suppressed by HC diets and only intake of 12.5% CP reversed this suppression. The most significant effects of CP on hepatic cholesterol, enzymes of hepatic cholesterol homeostasis, and the apolipoprotein B/E receptor were in animals fed the HC diets. These metabolic alterations partially explain the reduced plasma LDL of guinea pigs fed large amounts of CP.

Mice, hamsters and guinea pigs were studied to assess species variation in utilization of pyridoxine-5'-D-glucoside (PN-glucoside), a form of vitamin B-6 found in plants. Animals fed vitamin B-6-deficient or marginally supplemented diets [1 mg pyridoxine (PN)/kg] were given an oral dose of [3H]PN-glucoside plus [14C]PN. Urinary and fecal isotopic excretion was measured over 24 h and the distribution of B-6 vitamins in liver determined at the end of the 24-h period. Intestinal absorption was nearly complete, as very little (< 6%) of each isotope was excreted in the feces. In mice, hamsters and guinea pigs, 31.3, 31.5 and 9.5%, respectively, of urinary 3H was present as intact PN-glucoside. Incorporation into liver was reflected by 3H/14C ratios of hepatic vitamin B-6 as follows: mice, 0.39; hamsters, 0.73; guinea pigs, 1.49 (means for both diets). The intake of dietary vitamin B-6 had little effect on [3H]PN-glucoside metabolism. Guinea pigs displayed greater utilization of PN-glucoside than did mice, hamsters or rats (seen previously), although they may not be the best animal model for the study of PN-glucoside metabolism. Because the bioavailability of PN-glucoside in humans has been estimated to be 58% relative to PN, mice or hamsters, rather than guinea pigs or rats, would be better species for quantitative studies of PN-glucoside bioavailability and associated enzymatic processes.

Respiratory and Immunological Responses of Guinea Pigs to Enzyme-Containing Detergents: A Comparison of Intratracheal and Inhalation Modes of Exposure. Ritz, H. L., Evans, B. L. B., Bruce, R. D., Fletcher, E. R., Fisher, G. L., and Sarlo, K. (1993). Fundam. Appl. Toxicol. 21, 31-37. Guinea pigs were exposed once a week for 10 weeks by intratracheal exposure to solutions of 3, 1, 0.3, or 0.1 μg of the enzyme protein, Subtilisn Carlsberg (Alcalase), in 250 μg of a detergent base. Other groups of guinea pigs were exposed by inhalation (6 hr per day, 4 days a week) to 1 mg/m3 of the aerosolized detergent base containing either 3.5, 1.1, 0.3, or 0.1% Alcalase protein. Evaluations of gross respiratory responses immediately following each intratracheal exposure revealed a significant dose response in respiratory symptoms measurable after the fourth exposure and continuing throughout the study. In the inhalation experiment, during Weeks 4 through 10, animals were observed to have respiratory symptoms which were dependent upon both the dose of enzyme and on total exposure to the enzyme/detergent atmosphere. For both intratracheal and inhalation routes of exposure, the initial appearance of respiratory symptoms coincided with the first appearance of measurable serum allergic antibodies specific to Alcalase. The allergic antibody levels increased with time and dosage by both routes of exposure, and the antibody titers generated by the intratracheal administration of antigen were comparable to those generated by the inhalation route of exposure. These results indicate that the intratracheal technique is appropriate for the evaluation of the respiratory allergic response to a protein.

Autoradiographic Analyses of Guinea Pig Airway Tissues Following Inhalation Exposure to 14C-Labeled Methyl Isocyanate. Kennedy, A. L., Singh, G., Alarie, Y., and Brown, W. E. (1993). Fundam. Appl. Toxicol. 20, 57-67. Through the use of radioactively labeled methyl isocyanate (MIC), the deposition, penetration, and clearance of this highly reactive compound in the airway at the tissue and cellular levels have been directly examined. Guinea pigs were exposed to 14C-MIC vapors at concentrations ranging from 0.38 to 15.2 ppm for periods of 1-6 hr. Solubilization of tissues from these animals showed the airway tissues to have the highest level of radioactivity. In the nasal region, 14C deposition, as monitored by histoautoradiography, was limited to the epithelial layer, was related to dose, and was dependent on the specific epithelial cell type. The squamous epithelium was minimally labeled on the surface and the label did not penetrate the cell layer. However, radioactivity was detected throughout the entire nasal respiratory epithelial layer. The lack of nasal deposition in tracheotomized animals demonstrated that the 14C accumulation at this site was due to the scrubbing action of the nasal region with no contribution from blood recirculation. Cellular localization in the tracheobronchial region showed epithelial and subepithelial deposition in a dose-dependent manner with accumulation of the label at the subepithelial region. Radioactivity penetrated to the level of the terminal bronchiole but was not detected in the alveolar region. The persistence of airway radioactivity over the 48-hr postexposure period monitored suggests the covalent modification of airway macromolecules. Despite its broad specificity and high reactivity, MIC undergoes selective reactions in the airways which are dependent on respiratory region and cell type.

Zinc deficiency during pregnancy has severe effects in animals. To what extent the effects in animals apply to human pregnancy is not known. Because the pregnant guinea pig shares characteristics with pregnant women that make it a useful model, three experiments were done with guinea pigs in which Zn intake was reduced beginning on the 30th d of gestation. Reduced Zn intake in two of the three experiments resulted in abortion or premature delivery. Zinc-supplemented animals with feed intake restricted to that of Zn-deficient animals also aborted or delivered prematurely. Zinc-supplemented animals fed for ad libitum access delivered living young at term. Fetal/neonatal liver Zn concentration was low in the guinea pigs compared to that reported for other animals and was affected to a lesser extent by low Zn intake by the dam. Zinc concentration of neonatal plasma was also less than that in several other species. Change in activity of angiotensin-converting enzyme with addition of Zn in vitro was greater in the plasma of Zn-deficient guinea pigs than in that of Zn-adequate guinea pigs and may be useful as an indicator of Zn status.

Histamine suppresses certain immune responses, including neutrophil chemotaxis. The present study examined whether the histamine-lowering effect of ascorbate was accompanied by enhanced chemotaxis in guinea pigs. Animals were fed low ascorbate, adequate or high ascorbate diets (0.5, 2.0 or 50 mg ascorbate.100 g body wt-1.d-1) for 4 wk. Mean liver ascorbate paralleled dietary intake, and these values differed significantly. Blood histamine was significantly depressed in the high ascorbate group compared to the adequate and low ascorbate groups, and liver ascorbate was inversely correlated to blood histamine levels (r = -0.64, P less than 0.001). The random migration of neutrophils was not significantly affected by vitamin dosage. Leukocyte chemotaxis was significantly impaired in low ascorbate animals compared to that of animals with adequate ascorbate nutriture. Leukocyte chemotaxis in high ascorbate animals did not differ significantly from that in the adequate or low ascorbate groups. Furthermore, chemotaxis was significantly lower when cells extracted from animals with adequate ascorbate nutriture were incubated in low ascorbate or high ascorbate serum rather than in autologous serum. These data suggest that the histamine-lowering effect of supplemental ascorbate does not appear to enhance leukocyte chemotaxis and that serum from guinea pigs fed low or high levels of ascorbate appears to contain factors that depress chemotaxis.

We evaluated the effect of total parenteral nutrition (TPN) enriched with n-3 fatty acids on the physiologic response to endotoxin in guinea pigs. Animals were randomly assigned to receive TPN differing only in lipid source for 3.5 d. Group 1 received soybean fat emulsion (Intralipid) whereas group 2 received fish (menhaden) oil. During the last 7 h of TPN, animals were further randomized to have either saline or E coli endotoxin added to the infusate. Acid-base status and serum lactate concentrations were determined. Animals infused with soybean fat emulsions and endotoxin developed a significant metabolic acidosis, lactic acidemia, and decrease in mixed venous O2 compared with controls and fish-oil-treated animals (p less than 0.05). The significantly reduced serum lactate and higher mixed venous O2 in fish-oil-infused animals suggests that the underlying mechanism involves improvement in endotoxin-induced tissue hypoperfusion, presumably through alterations in prostaglandin metabolism.

Sulfur mustard (HD; 1,1′-thiobis[2-chloroethane]) induces fluid-filled blisters in man but not in conventional laboratory animals. An animal model is needed to emulate both cytotoxic (vesicant) and vascular (irritant) responses of human skin to HD exposures. An acceptable model must permit reproducible comparisons of uniformly graded and dose-related HD control responses with reduced responses that may follow antivesicant treatments. Hairless guinea pigs were evaluated by exposing six or eight dorsal skin sites 12 mm in diameter to similar HD vapor concentrations for graded intervals (1–16 min). HD vapor was delivered under occlusive caps holding 10 μl of HD in filter paper located 5 mm above the skin. Four-minute exposures induced moderate erythema, slight edema, and microblisters in 1 of 39 sites. Eight-minute exposures induced severe erythema, moderate edema, and microblisters in 31 of 40 sites. Gross blistering was not seen after use of vapor cups, but damage to basal cells resembled lesions of vesicant injury in man. The hairless guinea pig model, with graded HD vapor exposures, provides acceptable comparisons of responses. Exposures of both 4- and 8-min durations were used to show the feasibility of using this model to bioassay antivesicant topical protectants. These methods may be useful for measurements of irritant and cytotoxic responses of skin to other toxic vapors.

Certain dietary oils may have therapeutic potential in the treatment of inflammatory skin disorders. Presumably, the fatty acid constituents of these dietary oils exert their effects by altering the levels of cutaneous eicosanoids. Prompted by this possibility, we investigated whether supplementation of guinea pig diets with fish oil [rich in 20:5(n-3)] or borage oil [rich in 18:3(n-6)] could significantly alter epidermal levels of eicosanoids compared with control animals supplemented with olive oil. After feeding periods of 4, 8 or 12 wk, the epidermis from the animals was analyzed for: 1) fatty acid composition of individual epidermal phospholipids, 2) levels of lipoxygenase products, and 3) levels of cyclooxygenase products (prostaglandins). Our results demonstrated that the animals supplemented with dietary fish oil had elevated levels of 20:5(n-3) in epidermal phospholipids and elevated epidermal levels of 15-hydroxyeicosapentaenoic acid (15-HEPE) [the 15-lipoxygenase product of 20:5(n-3)] compared with guinea pigs fed olive oil or borage oil. Similarly, the animals supplemented with dietary borage oil had elevated levels of 20:3(n-6) [the epidermal elongase product of 18:3(n-6)] in epidermal phospholipids and elevated epidermal levels of 15-hydroxyeicosatrienoic acid [15-HETrE, the epidermal 15-lipoxygenase product of 20:3(n-6)] compared with guinea pigs fed olive oil or fish body oil. There were no significant changes in epidermal levels of prostaglandins. Both 15-HEPE and 15-HETrE have been identified as possible anti-inflammatory metabolites, and their elevated presence in the epidermis of animals fed oils rich in 20:5(n-3) or 18:3(n-6) may provide a mechanism for the beneficial effects of these oils on inflammatory conditions.

s / Placenta 35 (2014) A1eA112 A23 molecules in the fetal epithelium, and in the placental angiogenesis, despite the large distribution of the CAVs -1 and -2 in water buffalo placenta. Funding: FAPESP P1.40. DEVELOPMENT OF THE SUBPLACENTA IN GALEA SPIXII (RODENTIA, CAVIIDAE) Ferdinando Bezerra , Phelipe Favaron , Andrea Mess , Maria Angelica Miglino , Moacir de Oliveira a Department of Animal Science, Universidade Federal Rural do SemiArido, Mossoro, Rio Grande do Norte, Brazil; b Surgery Department, University of Sao Paulo, Sao Paulo, SP, Brazil The subplacenta of caviomorph rodents is considered to be the developmental origin for trophoblast invasion, which is relatively similar to the process in human beings. Objectives: We described subplacental development in a cavy species, Galea spixii. Methods: Tissues were collected from 12 females, ranging from day 15 to 55 of gestation. Samples were processed by means of histology, immunohistochemistry, cytochemistry, and electron microscopy. Results: On day 15 to 23, the subplacenta consisted of a single cytotrophoblast layer and a syncytium lining the maternal lacunae. Fetal circulation was present. On day 30, the subplacenta was more compact with well-defined border. Then it showed intense vascularisation. The lobules were composed by syncytiotrophoblast in the central part, and mesenchyme surrounded by cytotrophoblast at the borders of the organ. On day 45, degeneration of tissues was evident and syncytiotrophoblast was more abundant than cytotrophoblast. The syncytium was vacuolized and showed signs of apoptosis. Near term (days 53-55), more evident signs of cell death and reduction of subplacental tissue occurred. Proliferative activity of the subplacenta, evaluated by PCNA and AgNOR, was high early in early gestation and then continously decreased. Conclusion: In conclusion, the development of the subplacenta in Galea started early on reached a maximum around day 30 and became necrotic towards the end of gestation. Financial support: INCTC and NETCEM. P1.41-N. MORPHOLOGICAL AND VASCULAR CHANGES IN THE CORPUS LUTEUM DURING EARLY GESTATION OF BOVINE SCNT-DERIVED PREGNANCIES F abio Pinaffi, Izabelle Jardim, Juliano Sangalli, Rafael Sampaio, Flavio Meirelles, Luciano Silva University of Sao Paulo, Pirassununga, Sao Paulo

When guinea pigs are fed tissue-saturating amounts of ascorbate, C1q concentrations are significantly higher than in those animals fed only enough ascorbate for adequate growth and for the prevention of scurvy. C1q is the recognition protein of the classical complement pathway, a system of blood proteins that constitutes an important part of host defense against pathogens. The observed effect of ascorbate nutriture on C1q concentrations is consistent with the known role of ascorbic acid in hydroxyproline biosynthesis. C1q is a hydroxyproline-containing protein with structural similarities to collagen.

The purposes of this study were to use vocalization and posture as indices of the neuromuscular pathology that develops in zinc-deficient guinea pigs and to determine the rate of depletion before and of repletion after intraperitoneal (IP) zinc therapy. When severe signs of deficiency developed, tissues were analyzed for their zinc content to assess sites of depletable and mobilizable zinc stores. Weanling guinea pigs were fed low (less than 1 mg/kg) and adequate (100 mg/kg) zinc diets based on isolated soybean protein or autoclaved egg white. The first signs (stage 1) of vocalization due to handling, abnormal posture and skin lesions developed after approximately 4 wk. Severe (stage 3) signs followed after 5-6 wk. A single IP dose of ZnSO4 (50 mumol/kg) caused remission of signs within 4-5 d following which all signs regressed to stage 3 within 7 d. Analysis of 15 tissues from severely deficient guinea pigs showed that only plasma and bone had significantly lower zinc concentrations than tissues from comparable age-related controls fed a zinc-adequate diet. It seems unlikely that major soft tissues, such as muscle, brain, liver and skin, serve as mobilizable stores of zinc for other critical metabolic functions. Bone zinc is slowly mobilized but at a rate insufficient to maintain health or even life.

C57BL/6 mice treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 360 micrograms/kg) displayed a significant reduction in feed intake and body weight until just before death, when they developed ascites and subcutaneous edema. This caused body weight of the mice that died to suddenly increase during the terminal stage of toxicity. TCDD-treated mice that survived did not develop ascites or edema, and maintained a body weight that was slightly less than that of pair-fed mice. Cumulative lethality in TCDD-treated mice (69%) was greater than that of pair-fed controls (14%). In guinea pigs treated with TCDD (2 micrograms/kg) both the time course and magnitude of hypophagia were closely associated with weight loss. Pair-fed guinea pigs did not lose quite as much weight as TCDD-treated animals because their total body water content was higher. Water intake in pair-fed guinea pigs was greater than that of TCDD-treated animals. The time course and magnitude of lethality tended to be similar in TCDD-treated guinea pigs (81%) and pair-fed controls (64%). In Fischer F-344 rats treated with TCDD (100 micrograms/kg) body weight loss was associated with a reduction in both feed and water intake. The time course and magnitude of weight loss in TCDD-treated and pair-fed rats was essentially identical. Lethality was higher in TCDD-treated rats (95%) than pair-fed control animals (48%). Taken together, these findings suggest that hypophagia is responsible for the loss of adipose and lean tissue in mice, guinea pigs, and rats treated with a LD70-95 dose of TCDD. Under these dosage conditions, weight loss contributes more to the lethality of guinea pigs than to that of Fischer F-344 rats or C57BL/6 mice.

Topical formulations of acyclovir (ACV) were tested in animals to define potential for tissue irritation and systemic toxicity. Acyclovir ointments (5 and 10% concentrations in polyethylene glycol vehicle) produced no sign of dermal irritation or systemic toxicity when applied to shaved abraded and intact skin of guinea pigs for 24 consecutive days. Solutions (0.9% normal saline vehicle) of ACV did not sensitize guinea pigs when 10 sensitizing doses and a challenge dose were injected intradermally. Petrolatum base ophthalmic ointments containing 1 and 3% ACV did not produce significant ocular irritation when applied to the corneas of New Zealand White rabbits 5 times each day for 21 consecutive days. A 6% petrolatum base ointment produced mild conjunctival irritation but no sign of corneal or iridic toxicity. Mean concentrations of 2.53 microM ACV were found in aqueous humor 2 hours after a 1 cm ribbon (21 mg) of 3% ophthalmic ointment was placed in the eyes of rabbits. A single treatment with a topical ointment containing 5% ACV in polyethylene glycol vehicle produced minimal irritation when placed in the eyes of New Zealand White rabbits.

Exposure to paraquat, a widely used herbicide, has been shown to produce a concentration dependent rapid, shallow breathing pattern in guinea pigs 18 hr following exposure (H. Burleigh-Flayer and Y. Alarie 1987, Arch. Toxicol. , 59 (6), 391–396). To further explore the pulmonary effects following exposure to paraquat, two experiments were carried out. The first experiment consisted of exposing a group of guinea pigs for a period of 4 hr to 0.7 mg/m 3 paraquat aerosol and monitoring respiratory variables for 2 weeks following the exposure. In the second experiment, three groups of guinea pigs were repeatedly exposed to three concentrations of paraquat aerosol (0.1, 0.4, and 0.8 mg/m 3 ) for 6 hr a day, 5 days a week for 3 weeks. Respiratory variables were measured each day of these-3-week experiments. The respiratory variables evaluated in both experiments were tidal volume ( VT ) and respiratory frequency ( f ). These variables were monitored during air breathing and upon challenge with 10% CO 2 in 20% O 2 and 70% N 2 in order to evaluate the pulmonary effects of exposure to paraquat. Following a single exposure to 0.7 mg/m 3 paraquat aerosol, a decrease in VT and increase in f were seen during air and 10% CO 2 challenge which reached a maximum several days following exposure. After reaching maximal changes, the respiratory variables returned to control values. With repeated 6-hr exposures to paraquat aerosol. guinea pigs exposed to 0.4 and 0.8 mg/m 3 also displayed a rapid, shallow breathing pattern. Adaptation to the exposures for these two concentration groups was evidenced by a return of the respiratory variables toward control levels. This adaptation typically occurred during the first 7 days of exposures. A cumulative effect was therefore not detected with repeated exposures to paraquat aerosols.

Chronic protein insufficiency in utero was achieved by feeding to rat dams an 8% protein diet beginning before breeding and continuing until weaning. Thereafter, the in utero malnourished pups were fed the 8% protein diet. Superoxide dismutase (SOD), an enzyme which protects against superoxide radical, was quantitated in pellet and supernatant of polymorphonuclear leukocytes (PMN) and alveolar macrophages (AM). The AM of rats malnourished in utero contained 1.7 times as much protein and 3 times as much total SOD activity as the AM of control rats. In PMN of these rats, the amount of protein and SOD activity was the same. Significantly larger number of Streptococcus mutans were located from the dental plaque of the in utero malnourished rats. AM isolated from female guinea pigs fed a 9% protein diet from weaning at 11 days of age contained 1.5 times as much protein and twice as much SOD activity as AM from normal guinea pigs. However their PMN contained smaller amounts of total protein and SOD activity. The malnourished guinea pigs had a mammary gland infection and a prolonged conjunctival infection following inoculation with Guinea Pig Inclusion Conjunctivitis indicating that these animals were more susceptible to these infections. The increase in total SOD activity and in the total amount of protein in AM suggests that chronic protein insufficiency leads to susceptibility to infection and to macrophage activation but has no similar effects on PMN.

Bone formation under zinc deficiency conditions was investigated using alveolar implants in guinea pigs, from which bone formed solely during the period of zinc deficiency could be obtaned. Thirty-six guinea pigs (GP) weighing 175-195 g were randomly divided into three groups: group 1 received a -Zn diet, (1.0 +/- 0.2 ppm Zn); group 2 pair fed control, and group 3 ad libitum control. After 3 weeks of dietary treatment, the right incisor was extracted and a nylon mesh tube (1.0 cm long) was implanted into the incisor alveolar cavity. Two weeks after implantation, all GP were killed and bone-containing nylon implants (BCNIs) and femurs were removed for Zn, Ca and P analyses. Compared to the two control groups, -Zn group showed two to fourfold less zinc in femurs and in BCNIs, respectively. Femur, but not BCNI, from pair-fed GP had significantly higher zinc concentration than that of GP in group 3, Ca and P concentrations in -Zn BCNI were not significantly reduced, but P in -Zn femur was. When BCNIs were cultured for 48 hours in BGJ media containing 35SO4 or 14C-glucosamine, -Zn BCNIs incorporated significantly more 14C and slightly higher 35S into their glycosaminoglycan (GAG) fraction. It is concluded that under our standardized conditions zinc deficiency does not show an effect on Ca and P depositions into bone, but it seems to interfere with glycosaminoglycan metabolism of membranous bone.

Response surface methods were employed to model survival data obtained in guinea pigs following subcutaneous exposure to soman (GD; 30-84.6 micrograms/kg) with various treatment regimens (i.e., atropine/pralidioxime chloride [ATR/2-PAM] combinations, given im, 1 min post-GD). The analysis of the proportions of surviving animals in the various groups revealed that the use of individual treatment agents (i.e., ATR or 2-PAM) was effective in increasing survival. The level of GD exposure altered the nature of the ATR/2-PAM interaction. Exploration of the response surface indicates that the optimal treatment combinations (greater than 94% survival) of ATR/2-PAM change as a function of GD exposure in the following manner: GD 30 micrograms/kg-ATR/2-PAM, 217 mg/kg/0 mg/kg; GD 42.4 micrograms/kg-179/29 mg/kg; mg/kg; GD 60 micrograms/kg-148/83 mg/kg; GD 84.6 micrograms/kg-168/150 mg/kg. At higher exposures of GD (greater than 42.4 micrograms/kg), therapeutic synergy was observed with the use of the treatment combinations, as compared to optimal single agent treatments. Evaluation of the apparent toxicities of treatment combinations can also be determined in this procedure. RSM is not geometrically restricted by the number of variables under consideration. A variety of experimental designs, when used in conjunction with RSM, permit the modeling of multiple responses and provide estimates of optimal therapeutic modalities subject to constraints (e.g., behavioral toxicity).

Treatment of neonatal guinea pigs with cholestyramine persistently increases the activity of hepatic cholesterol 7 alpha-hydroxylase (CH-7 alpha), the rate-limiting enzyme of bile acid biosynthesis. In this study, we examined whether CH-7 alpha activity could be persistently inhibited by manipulations (chenodeoxycholic acid feeding) during neonatal life. Male Hartley guinea pigs (2-3 days old) were fed 0.25% chenodeoxycholic acid (CDCA)-supplemented diet for 10 days or 6 weeks. Feeding CDCA for 10 days increased plasma cholesterol [controls (C), 25 +/- 3 vs. CDCA, 34 +/- 2 mg/dl]. Bile acid pool in animals fed CDCA for 10 days was nearly fivefold greater than controls (C, 5.8 +/- 0.3 vs. CDCA, 29.1 +/- 0.9 mg/100 g body weight), whereas CH-7 alpha activity was almost completely inhibited [C, 1.83 +/- 0.4 vs. CDCA, 0.02 +/- 0.02 pmol/(mg . minute)]. Four weeks after stopping CDCA feeding, CH-7 alpha was greater in the CDCA-fed animals (C, 0.47 +/- 0.03 vs. CDCA, 0.67 +/- 0.05). This was associated with a greater bile acid pool in these animals (C, 3.0 +/- 0.2 vs. CDCA, 5.8 +/- 0.4). We conclude that CDCA fed to neonatal guinea pigs inhibits CH-7 alpha activity. This inhibition is not permanent, however, since CH-7 alpha activity increases following withdrawal from chronic CDCA feeding.

4,4′-Methylenedianiline (MDA) is an important chemical intermediate in the production of isocyanates and polyurethane elastomers and polymers. The health hazards from acute inhalation exposure to the aerosols were evaluated. Guinea pigs of albino and pigmented strains were exposed nose-only to the aerosols of MDA in polyethylene glycol 200 (PEG) solution. The exposure was 4 hr per day, 5 days per week for a total of 10 exposures in 2 weeks. The time-weighted average aerosol concentration was 0.44 ± 0.09 mg/liter and the optical number length mean diameter of the aerosol particle was 2.4μm with σg of 2.1. During exposures, no overt respiratory distress was observed. Two weeks after the exposures, the guinea pigs were tested for possible dermal sensitization by being challenged with dermal applications of MDA-PEG solutions at concentrations of 0, 2, 20, and 200 mg/ml. Neither dermal irritation nor allergic response was detected under this experimental condition. Thereafter, the animals were tracheostomized for measurements of changes in lung insufflation pressure for detecting possible changes in the distensibility of the lungs from a challenge dose of an aerosol of MDA-PEG at a concentration of 200 mg/ml. No significant changes were observed under this testing condition. Finally, the animals were euthanized for histopathologic examinations of eye, lung, liver, and kidney. The most remarkable finding was the degeneration of the inner and outer segments of the photoreceptor cells and the pigmented epithelial cell layer of the retinas of both albino and pigmented strains of guinea pigs. Since the retinal lesions in both strains of guinea pigs were similar, the retinal changes were, therefore, not related to the affinity between melanin and MDA. Examination of other tissues revealed small pulmonary granulomas or mild granulomatous pneumonitis in most MDA-exposed animals but no remarkable residual lesions in the liver and kidney 2 to 3 weeks postexposure.

In rats, the liver is the primary target organ of perfluoro-n-decanoic acid (PFDA) toxicity. Therefore, the effects of PFDA on hepatic ultrastructure were studied in rats. Pathological changes induced by PFDA in hamsters, mice, and guinea pigs were also examined. PFDA caused a severe reduction in body weight in all four species studied. A reduction in food intake was observed in rats and hamsters. However, hamsters continued to consume food at a reduced level, while rats stopped eating for a 5- to 6-day period about 6 days after dosing. The PFDA-induced pathological changes in the hamsters, mice, and guinea pigs resembled those seen in rats to varying degrees. As in the rat, PFDA caused a marked liver enlargement in mice and hamsters and a moderate swelling in guinea pigs. This hepatomegaly was ascribed primarily to individual cell swelling. Thymic atrophy was noted in PFDA-treated hamsters, mice, and guinea pigs. Seminiferous tubular degeneration observed in hamsters and guinea pigs, but not in mice, was not as severe as in the rat, where in some cases frank necrosis has been seen. Ultrastructural changes in the livers of all PFDA-treated animals, regardless of species, included disruption of the rough endoplasmic reticulum, rounding and swelling of the mitochondria with related structural alterations, and mild to extensive proliferation of peroxisomes. This peroxisome proliferative response was greatest in mice and almost absent in guinea pigs. Accumulation of lipid droplets in liver cells due to PFDA treatment was more pronounced in hamsters and guinea pigs than in rats and mice. PFDA-induced hepatomegaly with a concomitant increase in peroxisomes in several rodent species may be associated with an impairment of normal lipid metabolism in the liver by PFDA.

The hypothesis that the amino acid used for the conjugation of sulfolithocholate (S-LCA) is a critical determinant of its cholestatic potential was tested in the guinea pig which conjugates 90% of its bile acids with glycine. Twelve groups of animals were used to study the effect of taurine feeding at a concentration of 0.5� in the drinking water for periods of 1, 3, and 5 days before an iv injection of 18 �mmol/l00 g body weight of S-LCA. Bile flow was monitored in 30-mm aliquots over a 3-h period and the bile acid secretion as well as the glycine/taurine ratio of conjugated bile acids were determined. At the end of the various time periods, the livers were examined by light and electron microscopy. Within 3 days after taurine administration there was an increase in bile flow and a reversal of the glycine/taurine ratio with taurine conjugates becoming predominant. Liver morphology was unchanged except for a slight accumulation of lipids after 5 days of taurine feeding. In animals who were not pretreated with taurine, S-LCA injection led to a progressive decrease in bile flow such, that it was reduced to less than 20� at the end of the 3-h collection. 5-UCA was conjugated almost exclusively with glycine. In contrast, in the groups fed taurine for 1, 3, and 5 days before the 5-UCA injection, bile flow was comparable to that of the groups fed taurine alone. The S-LCA recovered in bile was to a large extent conjugated with taurine. S-LCA animals pretreated with taurine did not exhibit any liver cell changes while the group which had not received taurine before the S-LCA injection showed numerous cytoplasmic vacuoles with normal bile canaliculi. These data show that increasing the availability of taurine through dietary means may exert a protective effect against cholestasis induced by monohydroxy bile acids. Am J Clin Nutr l983;37:221-232.

Guinea pigs were maintained for various periods of time on low (0.5 mg/day), intermediate (20 mg/day), or high (100 and 500 mg/day) levels of dietary ascorbic acid. Animals in each experimental group were challenged with Candida al- bicans via cardiac injection, and the course of infection in the kidneys was assessed. The results show that the animals receiving only 0.5 mg of ascorbic acid per day were significantly more susceptible to the infection than animals maintained on any higher level of dietary ascorbic acid. The greater susceptibility of the guinea pigs in the 0.5- mg level group was evident, however, only during "early" stages of the infection (until about day 3). Guinea pigs receiving high levels of dietary ascorbic acid were no more resistant at any time after infection, or with any challenge dose, than those receiving an intermediate dietary level. Although these data suggest that vitamin C may be involved in resistance to candidiasis, tissue levels of ascorbic acid do not change sig nificantly with time after infection. These results indicate that low levels of dietary ascorbic acid increase susceptibility to candidiasis, yet high (or "megadose") levels of dietary vitamin C do not show any effect on resistance to this microorganism. J. Nutr. 113: 178-183, 1983.