Effects of vitamin A-deficiency and inflammation on the conducting airway epithelium of Syrian golden hamsters

The effects of vitamin A-deficiency and inflammation were studied in the conducting airways of Syrian golden hamsters. An important goal of the study was to characterize epithelial changes that occur early in vitamin A-deficiency, that might precede yet predispose to infection, and precipitate inflammatory changes in the lungs. Age-matched vitamin A-replete control and vitamin A-deprived hamsters were killed at 33 days of age (preweight-plateau); at 41 days of age (weight plateau-early weight loss); and at 48–55 days of age (prolonged weight plateau followed by weight loss). A tablet containing bromodeoxyuridine (BrdU) was implanted subcutaneously into each hamster 7 h before it was killed. No changes were seen in the conducting airway epithelium of vitamin A-deprived hamsters in the preweight plateau. However, labelling of secretory cells for BrdU was reduced 6–7 fold in the epithelium lining the lobar bronchus (p< 0.0002) and the bronchioles (p< 0.0001), and the proportions of ciliated cells were decreased (p<0.0001) at both airway levels in vitamin A-deficient hamsters in the weight plateau-early weight loss stage. Changes in cellular morphology were minimal in the intrapulmonary airway epithelium at this time but a few small focal patches of epidermoid metaplasia were seen in the tracheal epithelium. Small foci of inflammation were closely associated with the airways in the weight plateau, and the inflammation became more widespread when the deficiency was prolonged. The results suggest that the defense of the lungs to infection was impaired initially in the vitamin A-deficient hamsters by a widespread reduction in the numbers of ciliated cells throughout the epithelium of the conducting airways (trachea, bronchi, bronchioles). At the foci of inflammation, labelling of epithelial secretory cells for BrdU was greatly increased at all airway levels. A highly stratified cornifying epidermoid metaplasia developed in the tracheal epithelium, and goblet cell metaplasia developed in the cranial portion of the lobar bronchus, in association with submucosal inflammation. Goblet cell metaplasia appeared to be the only abnormality that wasnot reversed when vitamin A was restored to the diet. This is contribution no. 2911 from the Pathobiology Laboratory     

Severe acute respiratory syndrome coronavirus infection of golden Syrian hamsters

Small animal models are needed in order to evaluate the efficacy of candidate vaccines and antivirals directed against the severe acute respiratory syndrome coronavirus (SARS CoV). We investigated the ability of SARS CoV to infect 5-week-old Golden Syrian hamsters. When administered intranasally, SARS CoV replicates to high titers in the lungs and nasal turbinates. Peak replication in the lower respiratory tract was noted on day 2 postinfection (p.i.) and was cleared by day 7 p.i. Low levels of virus were present in the nasal turbinates of a few hamsters at 14 days p.i. Viral replication in epithelial cells of the respiratory tract was accompanied by cellular necrosis early in infection, followed by an inflammatory response coincident with viral clearance, focal consolidation in pulmonary tissue, and eventual pulmonary tissue repair. Despite high levels of virus replication and associated pathology in the respiratory tract, the hamsters showed no evidence of disease. Neutralizing antibodies were detected in sera at day 7 p.i., and mean titers at day 28 p.i. exceeded 1:400. Hamsters challenged with SARS CoV at day 28 p.i. were completely protected from virus replication and accompanying pathology in the respiratory tract. Comparing these data to the mouse model, SARS CoV replicates to a higher titer and for a longer duration in the respiratory tract of hamsters and is accompanied by significant pathology that is absent in mice. Viremia and extrapulmonary spread of SARS CoV to liver and spleen, which are seen in hamsters, were not detected in mice. The hamster, therefore, is superior to the mouse as a model for the evaluation of antiviral agents and candidate vaccines against SARS CoV replication.     

Ontogeny of endocrine cells in the respiratory system of Syrian golden hamsters

The ontogeny of protein gene product 9.5 (PGP 9.5), serotonin (5-HT), calcitonin gene-related peptide (CGRP), and calcitonin (CT) immunoreactivity was evaluated in small-granule endocrine cells of hamster laryngotracheal epithelium from fetal day 11 to adulthood. Two centrifugal (proximal-to-distal) patterns of differentiation occur. The first pattern begins during fetal life. Endocrine cells, single and clustered in groups (presumptive-or protoneuroepithelial bodies, pNEBs), initially colocalize immunostaining for PGP 9.5, 5-HT, and CGRP in the larynx and proximal 2/3 of the trachea on day 12 and spread to the caudal trachea on day 13.5-HT disappears fleetingly during the 24 h preceding birth; other-wise immunoreactivity for all three substances persists into adulthood. The clusters of endocrine cells survive beyond birth but are so diluted by expansion of the nonendocrine epithelium as to become inconspicuous. Since innervation was not actually observed, these clusters may persist as pNEBs, without developing connections to afferent or efferent nerve fibers. The second pattern concerns single small-granule cells stainable for CGRP but not for 5-HT. These cells first appear in the larynx and cartilaginous part of the cranial trachea on postnatal day 3, and in the middle and caudal trachea, on day 5. The cells increase in number on day 7. In adults, they predominate among endocrine cells of the cartilaginous region. A subset of these cells begins to co-express CT proximally on postnatal day 10, reaching the caudal end of the trachea by 3 weeks. A few elements of the older 5-HT-positive population may also become immunoreactive for CT in juvenile hamsters.     

Ontogeny of endocrine cells in the respiratory system of Syrian golden hamsters

The ontogeny of protein gene product 9.5 (PGP 9.5), serotonin (5–HT), calcitonin gene-related peptide (CGRP), and calcitonin (CT) immunoreactivity was evaluated in small-granule endocrine cells of hamster laryngotracheal epithelium from fetal day 11 to adulthood. Two centrifugal (proximal-to-distal) patterns of differentiation occur. The first pattern begins during fetal life. Endocrine cells, single and clustered in groups (presumptive- or protoneuroepithelial bodies, pNEBs), initially co-localize immunostaining for PGP 9.5, 5–HT, and CGRP in the larynx and proximal 2/3 of the trachea on day 12 and spread to the caudal trachea on day 13. 5–HT disappears fleetingly during the 24 h preceding birth; otherwise immunoreactivity for all three substances persists into adulthood. The clusters of endocrine cells survive beyond birth but are so diluted by expansion of the nonendocrine epithelium as to become inconspicuous. Since innervation was not actually observed, these clusters may persist as pNEBs, without developing connections to afferent or efferent nerve fibers. The second pattern concerns single small-granule cells stainable for CGRP but not for 5–HT. These cells first appear in the larynx and cartilaginous part of the cranial trachea on postnatal day 3, and in the middle and caudal trachea, on day 5. The cells increase in number on day 7. In adults, they predominate among endocrine cells of the cartilaginous region. A subset of these cells begins to co-express CT proximally on postnatal day 10, reaching the caudal end of the trachea by 3 weeks. A few elements of the older 5–HT-positive population may also become immunoreactive for CT in juvenile hamsters.     

Triiodothyronine and vitamin A-deficiency in the rat

The total (TT3) and free serum triiodothyronine (fT3) and the distribution of a tracer dose of 125I-T3 were studied in rats on a vitamin A-deficient diet. After 6 weeks on the diet there was an increased serum T3 (TT3 and fT3). But after injection of 125I-T3 a smaller radioactivity was counted in kidney and liver of deficient animals, thus revealing a smaller transport of T3 into the target cells. So vitamin A-deficiency induces an original hormonal status responsible for the conflicting metabolic changes already described in deficient rats.     

Dehydroepiandrosterone-induced reduction of Cryptosporidium parvum infections in aged Syrian golden hamsters.

Cryptosporidiosis, a parasitic disorder caused by Cryptosporidium parvum, is frequently a fulminating and life-threatening disease in immunocompromised hosts. The immune status of the host plays a critical role in determining the length and severity of the disease. Dehydroepiandrosterone (DHEA) is an immunomodulator that has been demonstrated to upregulate immune parameters. Ten aged (20-24 mo) Syrian golden hamsters were treated with DHEA for 7 days prior to intragastric inoculation with 1 x 10(6) C. parvum oocysts. An additional 10 aged hamsters were infected similarly but retained as untreated controls. The untreated hamsters presented with generalized infections as determined by oocyst shedding in the feces and parasite colonization of the small intestine. Hamsters treated with DHEA exhibited a significant reduction in cryptosporidial infection when compared to untreated hamsters. These results suggest that DHEA may be an effective prophylactic agent for cryptosporidiosis in immunocompromised patients.     

Electrophysiological studies on the cultured cells obtained from transplantable pancreatic carcinoma in Syrian golden hamsters

A pancreatic ductal carcinoma was established as a transplantable tumor line in an inbred strain of Syrian golden hamsters. Intracellular recordings of membrane potentials and input resistance were made from cultured cells obtained from the transplanted tumors using indwelling glass microelectrode. The mean value of the resting membrane potential was -46.5 +/- 1.8 mV (S.E.) (n = 13), while the mean resting input resistance was 21.2 +/- 4.3 M omega (S.E.) (N = 13). Dibutyryl cyclic AMP (2 X 10(-3)M) caused a marked hyperpolarization of about 30 mV accompanied by a reduction of input resistance. The transplantable tumor and its cultured cell line developed in this study have demonstrated their effectiveness as a reliable experimental model for use in pancreatic cancer research.     

Soyasaponins lowered plasma cholesterol and increased fecal bile acids in female golden Syrian hamsters

A study was conducted in hamsters to determine if group B soyasaponins improve plasma cholesterol status by increasing the excretion of fecal bile acids and neutral sterols, to identify group B soyasaponin metabolites, and to investigate the relationship between a fecal group B soyasaponin metabolite and plasma lipids. Twenty female golden Syrian hamsters, 11-12 weeks old and 85-125 g, were randomly assigned to a control diet or a similar diet containing group B soyasaponins (containing no isoflavones), 2.2 mmol/kg, for 4 weeks. Hamsters fed group B soyasaponins had significantly lower plasma total cholesterol (by 20%), non-high-density lipoprotein (HDL) cholesterol (by 33%), and triglycerides (by 18%) compared with those fed casein (P < 0.05). The ratio of total cholesterol to HDL cholesterol was significantly lower (by 13%) in hamsters fed group B soyasaponins than in those fed casein (P < 0.05). The excretion of fecal bile acids and neutral sterols was significantly greater (by 105% and 85%, respectively) in soyasaponin-fed hamsters compared with those fed casein (P < 0.05). Compared with casein, group B soyasaponins lowered plasma total cholesterol levels and non-HDL cholesterol levels by a mechanism involving greater excretion of fecal bile acids and neutral sterols. Hamsters fed group B soyasaponins statistically clustered into two fecal soyasaponin metabolite-excretion phenotypes: high excreters (n = 3) and low excreters (n = 7). When high and low producers of this soyasaponin metabolite were compared for plasma cholesterol status, the high producers showed a significantly lower total-cholesterol-to-HDL-cholesterol ratio compared with the low producers (1.38 +/- 0.7 vs. 1.59 +/- 0.13; P < 0.03). Greater production of group B soyasaponin metabolite in hamsters was associated with better plasma cholesterol status, suggesting that gut microbial variation in soyasaponin metabolism may influence the health effects of group B soyasaponins.     

Uptake dynamics of scrapie agent in the intestinal villous epithelium of suckling and weanling Syrian hamsters

In mice, the number of intestinal villous columnar epithelium cells that incorporate abnormal prion protein (PrP(Sc) ) decreases significantly after weaning. In this study, the dynamics of PrP(Sc) uptake during the growth of hamsters were investigated by inoculating scrapie 263K agent orally into suckling and weanling Syrian hamsters and estimating the number of PrP(Sc) -positive villous epithelium cells immunohistochemically. The number of PrP(Sc) -positive cells declined significantly as the hamsters aged. The present results suggest that a tendency toward decline of PrP(Sc) -positive cells with increasing age might be a common phenomenon among the superfamily Muridae.     

A live attenuated severe acute respiratory syndrome coronavirus is immunogenic and efficacious in golden Syrian hamsters

The immunogenicity and protective efficacy of a live attenuated vaccine consisting of a recombinant severe acute respiratory syndrome (SARS) coronavirus lacking the E gene (rSARS-CoV-ΔE) were studied using hamsters. Hamsters immunized with rSARS-CoV-ΔE developed high serum-neutralizing antibody titers and were protected from replication of homologous (SARS-CoV Urbani) and heterologous (GD03) SARS-CoV in the upper and lower respiratory tract. rSARS-CoV-ΔE-immunized hamsters remained active following wild-type virus challenge, while mock-immunized hamsters displayed decreased activity. Despite being attenuated in replication in the respiratory tract, rSARS-CoV-ΔE is an immunogenic and efficacious vaccine in hamsters.     

Enzymatic synthesis of biopterin from D-erythrodihydroneopterin triphosphate by extracts of kidneys from Syrian golden hamsters.

An enzyme system was found in either crude homogenates of dialyzed extracts of liver, kidney, lung, and brain from Syrian golden hamsters that catalyzed the synthesis of radioactive 6(L-erythro-1',2'-dihydroxypropyl)pterin (biopterin) from [U-14C]6(D-erythro-1',2',3'-trihydroxypropyl)-7,8-dihydropterin triphosphate (D-erythrolH2neopterin-PPP) preparation. The specific radioactivity of biopterin was found to be comparable to that of D-erythroH2neopterin-PPP. The enzyme system from hamster kidney was purified severalfold by fractionation with ammonium sulfate and with an Ultrogel AcA-34 column. It was demonstrated that (a) NADPH or NADAH was essential and that (b) Mg2+ was stimulatory for the enzymatic synthesis of biopterin from D-erythroH2-NEOPTERIN-PPP. Also GTP and nonphosphorylated neopterins were not converted to biopterin. Although 6-lactyl-7,8-dihydropterin (sepiapterin) was converted to biopterin in the presence of NADPH, sepiapterin was not detected from D-erythroH2neopterin-PPP in the absence of NADPH. A preliminary experiment was performed to identify dihydrobiopterin.     

Intraperitoneal injection of chloral hydrate causes intra-abdominal adhesions and unilateral testicular atrophy in golden Syrian hamsters.

We investigated the reason for the high mortality we had observed in hypophysectomized-orchidectomized Golden Syrian hamsters that were anesthetized with intraperitoneal (i.p.) injections of chloral hydrate (CH). Intact male Golden Syrian hamsters were injected intraperitoneally with 0.1cc/100g BW of a 35% solution of CH, a 35% solution of sodium chloride, or double-distilled water. Equal numbers of hamsters in each group were injected on the right or left side of the abdomen. Within 10 days, 35% of the CH-injected hamsters were dead or had to be euthanized. Autopsy revealed severe peritonitis and adynamic ileus. CH-injected hamsters that survived gained weight at a rate similar to that of the controls. All surviving hamsters were killed 18 days after the injections. Among the surviving CH-injected hamsters, 84.6% had intra-abdominal adhesions, 61.5% had unilateral testicular atrophy, and 53.8% had a yellowish necrotic mass in the epididymal fat pad (EFP). All the lesions occurred on the side that was injected. The atrophied testes had been rendered cryptorchid due to involvement with intra-abdominal adhesions. In the water-treated controls, there were no abnormalities; whereas, in the saline controls, 75% had a mass in the EFP. Histology of the EFP mass was similar in hamsters injected with CH or hypertonic saline and suggested a diagnosis of fat necrosis. The results suggest that the mortality, the intra-abdominal adhesions, and the unilateral cryptorchidism were caused by a single i.p. injection of CH, but the fat necrosis in the EFP was probably caused by high concentrations of salt. The results further suggest that high concentrations of CH should not be injected intraperitoneally for anesthesia in chronic studies, particularly of the male reproductive system.