Donald D. Smith

PREVALENCE OF ANTIBODIES TO TOXOPLASMA GONDII IN WILD MAMMALS OF MISSOURI AND EAST CENTRAL KANSAS: BIOLOGIC AND ECOLOGIC CONSIDERATIONS OF TRANSMISSION

Sera from 273 wild mammals from Missouri and Kansas (USA), collected between December 1974 and December 1987, were tested for the presence of antibodies to Toxoplasma gondii using the Sabin-Feldman dye test. Sixty-five (24%) had antibodies at titers of ≥ 1:8, including 38 (66%) of 58 carnivores, 14 (15%) of 94 omnivores, 13 (11%) of 117 herbivores, and none of four insectivores. The prevalence of antibodies in mice (Mus musculus and Peromyscus spp.) and rats (Rattus norvegicus and Sigmodon hispidus) was low (3%), while medium sized herbivores such as squirrels (Sciurus spp.), rabbits (Sylvilagus floridanus), and muskrats (Ondatra zibethicus) had prevalences of about 18%. Red foxes (Vulpes fulva) and mink (Mustela vison) had the highest prevalence of antibodies with frequencies of 90 and 66%, respectively. In 32 attempts to isolate Toxoplasma gondii from wild mammals with positive (≥1:4) titers, only six (19%) were successful: a gray squirrel (Sciurus carolinensis), a beaver (Castor canadensis), an opossum (Didelphis marsupialis), a red fox and two mink. These findings are consistent with the hypothesis that the probability of infection with Toxoplasma gondii, and therefore prevalence of antibodies in wildlife, is greatest in carnivores.

Mast cell deficiency attenuates progression of atherosclerosis and hepatic steatosis in apolipoprotein E-null mice

Mast cells are important cells of the immune system and are recognized as participants in the pathogenesis of atherosclerosis. In this study, we evaluated the role of mast cells on the progression of atherosclerosis and hepatic steatosis using the apolipoprotein E-deficient (ApoE(-/-)) and ApoE(-/-)/mast cell-deficient (Kit(W-sh/W-sh)) mouse models maintained on a high-fat diet. The en face analyses of aortas showed a marked reduction in plaque coverage in ApoE(-/-)/Kit(W-sh/W-sh) compared with ApoE(-/-) after a 6-mo regimen with no significant change noted after 3 mo. Quantification of intima/media thickness on hematoxylin and eosin-stained histological cross sections of the aortic arch revealed no significant difference between ApoE(-/-) and ApoE(-/-)/Kit(W-sh/W-sh) mice. The high-fat regimen did not induce atherosclerosis in either Kit(W-sh/W-sh) or wild-type mice. Mast cells with indications of degranulation were seen only in the aortic walls and heart of ApoE(-/-) mice. Compared with ApoE(-/-) mice, the serum levels of total cholesterol, low-density lipoprotein and high-density lipoprotein were decreased by 50% in ApoE(-/-)/Kit(W-sh/W-sh) mice, whereas no appreciable differences were noted in serum levels of triglycerides or very low density lipoprotein. ApoE(-/-)/Kit(W-sh/W-sh) mice developed significantly less hepatic steatosis than ApoE(-/-) mice after the 3-mo regimen. The analysis of Th1/Th2/Th17 cytokine profile in the sera revealed significant reduction of interleukin (IL)-6 and IL-10 in ApoE(-/-)/Kit(W-sh/W-sh) mice compared with ApoE(-/-) mice. The assessment of systemic generation of thromboxane A(2) (TXA(2)) and prostaglandin I(2) (PGI(2)) revealed significant decrease in the production of PGI(2) in ApoE(-/-)/Kit(W-sh/W-sh) mice with no change in TXA(2). The decrease in PGI(2) production was found to be associated with reduced levels of cyclooxygenase-2 mRNA in the aortic tissues. A significant reduction in T-lymphocytes and macrophages was noted in the atheromas of the ApoE(-/-)/Kit(W-sh/W-sh) mice. These results demonstrate the direct involvement of mast cells in the progression of atherosclerosis and hepatic steatosis.

Mast cell granules potentiate endotoxin-induced interleukin-6 production by endothelial cells.

Mast cells are constituent cells of vascular tissue and their numbers are increased in atherosclerotic vessels. To gain insight into the role of mast cells in vascular inflammation, the effect of mast cell granules (MCG) on endothelial cell production of interleukin‐6 (IL‐6) was examined. Human umbilical vein endothelial cells (HUVEC) were cultured with lipopolysaccharide (LPS) in the presence or absence of rat peritoneal MCG and IL‐6 production was assayed by enzymelinked immunosorbent assay. The interaction of MCG with HUVEC in culture was examined by electron microscopy (EM). The EM studies revealed that MCG are internalized by HUVEC and appear intact even after 24 h in culture. Unactivated HUVEC produced little or no IL‐6 either in the presence or absence of MCG. Treatment of HUVEC with LPS stimulated IL‐6 production in a dose‐ and time‐dependent fashion. Addition of MCG to LPS‐activated HUVEC resulted in the potentiation of IL‐6 production at all LPS doses. MCG‐induced enhancement of IL‐6 production was evident even at a mast cell‐to‐endothelial cell ratio of 1:32. The enhancement of IL‐6 production by MCG was also seen when tumor necrosis factor α was used as an activator. Although potentiation was evident when MCG were added 6 h before or after LPS stimulation, the maximum effect was noted when MCG and LPS were added simultaneously. MCG‐mediated enhancement of IL‐6 production was abrogated by pretreating MCG with protease inhibitors. Although MCG proteases potentiate IL‐6 production by HUVEC, they do not degrade secreted IL‐6. These results demonstrate that MCG interact with endothelial cells and modulate the production of an important inflammatory cytokine. J. Leukoc. Biol. 62: 210–216; 1997.

Regulation of the expression of adhesion molecules by human synoviocytes

The capacity of synoviocytes to participate in inflammatory responses may be altered by the cytokine-enhanced expression of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1). To examine this possibility, the ability of selected cytokines to enhance ICAM-1 expression was examined. The data indicated that each of these cytokines (interleukin-1 beta greater than tumor necrosis factor-alpha, interferon-gamma much greater than interleukin-6) can up-regulate synoviocyte ICAM-1 expression. This can potentially increase the ability of these cells to interact with infiltrating inflammatory cells, thereby propagating immunologically mediated inflammation such as occurs in rheumatoid synovitis.

Effects of Radiation on a Fenced Population of Horned Lizards (Phrynosoma platyrhinos) in Southern Nevada

Between 1964 and 1966 minimum spring densities of horned lizards ranged from 1.0-2.5/hectare (ha) in 3 8 ha enclosures in Rock Valley, Nevada. Minimal survival of hatchling horned lizards to the age of 8 months was about 26-38 per cent. Annual minimal survival of older lizards was 50-60 per cent. Female horned lizards usually laid one clutch of eggs per year, but multiple clutches were observed in 1969. Conversely, no reproduction was observed in 1970. The maximum life span of horned lizards is at least 94 months. One of the enclosures was subjected to continuous gamma irradiation from a centrally located source of 137Cs. Between 1964 and 1966 numbers of horned lizards declined in all 3 plots. Between 1967 and 1970 numbers of horned lizards increased in the two control areas, but continued to decline in the irradiated plot. Female sterility owing to regression of ovaries is judged to be the cause of the population decline. Similar radiation effects have previously been observed among leopard lizards (Crotaphytus wislizenii), whiptail lizards (Cnemidophorus tigris), and side-blotched lizards (Uta stansburiana). * * *

H1-antihistamines exacerbate high-fat diet-induced hepatic steatosis in wild-type but not in apolipoprotein E knockout mice

We examined the effects of two over-the-counter H1-antihistamines on the progression of fatty liver disease in male C57Bl/6 wild-type and apolipoprotein E (ApoE)-/- mice. Mice were fed a high-fat diet (HFD) for 3 mo, together with administration of either cetirizine (4 mg/kg body wt) or fexofenadine (40 mg/kg body wt) in drinking water. Antihistamine treatments increased body weight gain, gonadal fat deposition, liver weight, and hepatic steatosis in wild-type mice but not in ApoE-/- mice. Lobular inflammation, acute inflammation, and necrosis were not affected by H1-antihistamines in either genotype. Serum biomarkers of liver injury tended to increase in antihistamine-treated wild-type mice. Serum level of glucose was increased by fexofenadine, whereas lipase was increased by cetirizine. H1-antihistamines reduced the mRNA expression of ApoE and carbohydrate response element-binding protein in wild-type mice, without altering the mRNA expression of sterol regulatory element-binding protein 1c, fatty acid synthase, or ApoB100, in either genotype. Fexofenadine increased both triglycerides and cholesterol ester, whereas cetirizine increased only cholesterol ester in liver, with a concomitant decrease in serum triglycerides by both antihistamines in wild-type mice. Antihistamines increased hepatic levels of conjugated bile acids in wild-type mice, with the effect being significant in fexofenadine-treated animals. The increase was associated with changes in the expression of organic anion transport polypeptide 1b2 and bile salt export pump. These results suggest that H1-antihistamines increase the progression of fatty liver disease in wild-type mice, and there seems to be an association between the severity of disease, presence of ApoE, and increase in hepatic bile acid levels.

Four new coccidia (Apicomplexia: Eimeriidae) from anoles (Lacertilia: Polychrotidae) in the Dominican Republic.

Fecal samples from 25 Anolis armouri, 2 Anolis bahorucoensis, 48 Anolis cybotes, and 21 Anolis olssoni (Lacertilia: Polychrotidae) from southern Hispaniola were examined for coccidian oocysts. Two eimerians and 2 isosporans are herein described as new species. Sporulated oocysts of Eimeria schwartzi n. sp. from A. armouri are ellipsoidal, 22.7 (20.8-25.0) x 15.7 (14.6-17.7) microns, with spherical to subspherical sporocysts, 7.9 (6.2-9.4) x 7.4 (6.2-8.3) microns. Sporulated oocysts of Isospora reui n. sp. from A. bahorucoensis are spherical to subspherical, 18.2 (15.6-20.0) x 17.8 (15.6-19.8) microns, with ovoid sporocysts, 11.9 (10.4-12.7) x 8.5 (7.5-9.4) microns. Sporulated oocysts of Isospora hendersoni n. sp. from A. armouri and A. cybotes are spherical to subspherical, 23.2 (20.8-26.0) x 21.1 (18.4-23.9) microns, with ellipsoidal sporocysts, 14.7 (12.5-15.6) x 10.0 (9.2-11.4) microns. Sporulated oocysts of Eimeria avilae n. sp. from A. olssoni are cylindrical, 29.3 (26.0-33.3) x 15.9 (13.5-18.9) microns, with ellipsoidal sporocysts 10.2 (9.4-11.4) x 6.8 (5.2-8.0) microns.

Chronic Ingestion of H1-Antihistamines Increase Progression of Atherosclerosis in Apolipoprotein E-/- Mice

Although increased serum histamine levels and H1R expression in the plaque are seen in atherosclerosis, it is not known whether H1R activation is a causative factor in the development of the disease, or is a host defense response to atherogenic signals. In order to elucidate how pharmacological inhibition of histamine receptor 1 (H1R) signaling affects atherogenesis, we administered either cetirizine (1 and 4 mg/kg. b.w) or fexofenadine (10 and 40 mg/kg. b.w) to ApoE−/− mice maintained on a high fat diet for three months. Mice ingesting a low dose of cetirizine or fexofenadine had significantly higher plaque coverage in the aorta and cross-sectional lesion area at the aortic root. Surprisingly, the higher doses of cetirizine or fexofenadine did not enhance atherosclerotic lesion coverage over the controls. The low dose of fexofenadine, but not cetirizine, increased serum LDL cholesterol. Interestingly, the expression of iNOS and eNOS mRNA was increased in aortas of mice on high doses of cetirizine or fexofenadine. This may be a compensatory nitric oxide (NO)-mediated vasodilatory mechanism that accounts for the lack of increase in the progression of atherosclerosis. Although the administration of cetirizine did not alter blood pressure between the groups, there was a positive correlation between blood pressure and lesion/media ratio at the aortic root in mice receiving the low dose of cetirizine. However, this association was not observed in mice treated with the high dose of cetirizine or either doses of fexofenadine. The macrophages or T lymphocytes densities were not altered by low doses of H1-antihistamines, whereas, high doses decreased the number of macrophages but not T lymphocytes. The number of mast cells was decreased only in mice treated with low dose of fexofenadine. These results demonstrate that chronic ingestion of low therapeutic doses of cetirizine or fexofenadine enhance progression of atherosclerosis.

Agonistic responses by a grass anole, Anolis olssoni from the Dominican Republic, to male conspecifics

Agonistic behaviour of male Anolis olssoni was elicited in natural habitats near Baraona, Barahona Province, Dominican Republic, through the introduction of tethered males. Videotaped responses consisted of various sequences and combinations of behaviours and modifiers and appeared to vary according to levels of arousal. Male A. olssoni assume a posture involving full head elevation and dewlap extension, which apparently signals the highest state of arousal to conspecifc males. This display was invariably accompanied by gaping with a protruded tongue, distinct extension of nuchal and dorsal crests, bulging eyes, and changes in body and tail colouration. Analysis of behaviours failed to identify a stereotypical display for this species. Males apparently monitor and defend their immediate surroundings, a strategy which may be adaptative in a densely occupied and complex microhabitat in which vision is restricted.

Intradermal infestation of a red fox (Vulpes vulpes) by the lone star tick (Amblyomma americanum).

Numerous small dark spots and nodules were observed on the visceral side of the skin of a red fox (Vulpes uulpes), captured in December 1982,4.5 km north of Kingsville, Johnson County, Missouri. Upon closer examination the spots were determined to be ticks located in the dermis and hypodermis. Approximately 25 were adults and nymphs, and over 200 larval ticks were present. Specimens of the ticks were excised and placed in 70% isopropyl alcohol; some were embedded in paraffin, sectioned, and stained with hematoxylin and eosin (H&E). Several ticks were independently keyed by the authors, and a specimen was sent to The Veterinary Diagnostic Laboratory, Kansas State University for confirmation. All ticks were identified as Amblyomma americanum. Most were present in the axilla and groin with the larval ticks predominating in the groin and perineal regions, while the larger ticks were most common in the axillary area (Fig. 1). No inflammation was present around individual ticks, although a reddening of the skin was apparent externally in the groin region of the left leg, possibly due to scratching of the area by the fox. The white spot on the scutum of some of the female ticks was visible from the inner side of the skin, indicating that they were upside down relative to their typical attachment. The sectioned ticks were found enclosed totally by several layers of squa-