The tectal lamination was investigated in the central part of the chick embryonic tectum. Two and 5 layers were observed above the neuroepithelium (NE) on embryonic day 6 (E6) and E8, respectively. Optic fibers extended on the surface of the tectum by E8. On E10-11, the outer tectum was composed of 2 layers, that is, a fibrous layer forming the optic fiber layer on the tectal surface and a cellular layer showing the gradient of cell density. In the inner tectum, the lamination was almost completed. On E12-13, the outer tectal layers, which showed the gradient of cell density, was divided into dark and light cellular layers. The dark cellular layer was divided into 2 layers on E14-15 and further into 4 layers (layer C-F in chick) on E18. On the other hand, the light cellular layer did not change until E18, but finally, it was divided into 2 layers (layer A and B in chick) by E20. Optic fibers reached the bottom of the outer tectum by E14 showing different densities of terminals. Stratification by optic fibers was going to step into the final stage on E18. On E20, laminations according to cytoarchitectural features and the optic fiber terminals were substantially completed. In the tectum affected by destruction of the contralateral embryonic eye (E4), some cellular layers were incompletely discriminated by differences of cell density.
The skull size and shape were osteometrically examined in the four species of the tree shrews (Tupaia tana, T. javanica, T. minor and T. dorsalis). We suggest that the skull characters were affected by the species specific behavior and terrestrial, arbo-terrestrial and arboreal life, among the genus Tupaia. The neurocranium was laterally narrower in the braincase area, and the splanchnocranium was longer only on dorsal side in T. tana, and these characters were opposite to T. minor. The principal component analysis confirmed the obviously separated clusters among T. tana, T. javanica and T. minor, affected by the adaptation for each behavior. T. dorsalis was considered as terrestrial species from the results of proportion analysis and the principal component analysis.
The hump attachment structure was morphologically examined in the two-humped camel (Camelus bactrianus). The cranial hump is fixed by the trapezius and rhomboid muscles in the thoracic region. The strong collagen sheet in the basement of the hump is attached to the segmented bellies of the trapezius muscle, and the thoracic rhomboid muscle and the nuchal-supraspinous ligament support the attachment function of the trapezius muscle. The basement sheet possesses the line structure of collagen fibers, which are fitted to the segmented bundles of the trapezius muscle, and we observed that the muscle cells of the trapezius muscle are intermingled with the collagen fibers around the attachment line structure. In contrast, the caudal hump is directly attached to the subcutaneous tissue in the superficial region of the lumbar longissimus and lumbar iliocostal muscles. These findings demonstrated that the caudal hump of the two-humped camel is consistent with the hump of the one-humped camel in the attachment structure.
Ambulatory electrocardiogram (ECG) has been recorded in dogs wearing a jacket to protect a Holter recording system, but the jacket was often damaged by dogs. We compared ECG recorded by a Holter recording system and spontaneous activity measured by an accelerometer in Beagle dogs with or without an Elizabethan collar. There were few significant differences in mean values (per hr) of the heart rate and the amount of spontaneous activity between dogs with or without the Elizabethan collar. Mean values (per 23 hr) of them had no significant difference between them. We concluded that the Elizabethan collar did not have any effect on ambulatory ECG and canine movements and was effective to protect the recording apparatus.
We isolated Cryptosporidium parvum-type oocysts from naturally infected siberian chipmunks which originated in the People's Republic of China and examined the infectivity to rodents as experimental animals. The naturally infected chipmunks did not show any clinical symptoms. The oocysts were 4.8 × 4.2 μm on average in size. They were ovoid and morphologically similar to the C. parvum oocysts isolated from human and cattle. Experimental rodents were inoculated with 1.6 × 106 original oocysts each. SCID mice began to shed oocysts on day 7 and the OPG value was 105 from 50 days. The oocysts were found from ICR mice on days 13 and 16 by only sugar flotation method, however, any oocysts were not detected from the rats, guinea pigs and rabbits until 30 days. Two infected SCID mice were necropsied on days 100 and 102 and examined for coccidian organisms. Merozoites and oocysts were found in the low part of jejunum and ileum, however, no parasites were detected in the stomach. Consequently, it was considered that the present species was C. parvum and was probably genotype 2 from result of infectivity to rodents.
Neospora caninum (BT-2 strain) that originated from the brain of a Holstein calf was serially passaged through 10 generations of BALB/c nude mice by intraperitoneal inoculation. Histological examination of the mice revealed that numerous clusters of tachyzoites appeared in the pancreas, stomach and small intestine as well as in the central nervous system (CNS) and skeletal muscles. Intestinal contents of the infected mice were inoculated intraperitoneally into uninfected nude mice and 3 of the 17 inoculated mice showed clinical signs at post inoculation days 3 to 10. The present experiments demonstrated a proliferation of N. caninum tachyzoites in the mucosa of the alimentary tract and pancreas of the nude mice and the intestinal contents of the mice were infective to other nude mice.
A subcutaneous malignant fibrous histiocytoma (MFH) was observed in the region between the right posterior trunk and right hind limb of a 2-year-old male Djungarian hamster weighing 45 g. Histologically, the tumor consisted of bizarre multinucleated giant cells, histiocytic cells, and fibroblastic cells with a storiform pattern, and was considered to be of the storiform-pleomorphic type of MFH. Severe nuclear atypia with prominent nucleoli and many mitotic figures was also observed. Electron microscopy demonstrated fibroblastic cells and histiocytic cells. The fibroblastic cells were spindle-shaped, and sometimes had an invaginated nucleus. The histiocytic cells were polygonal with an oval or kidney-shaped nucleus. The cytoplasm of both cells contained numerous free ribosomes, small amounts of rough endoplasmic reticulum, and round mitochondria. Tumor cells were immunohistochemically positive for vimentin, and were thought to be of undifferentiated mesencymal cell origin. This is the first report of spontaneous MFH in a hamster.
Composition of glycoconjugates were investigated in Escherichia coli 09:K103:NM, 987P+ST+-infected lower small intestines of 1-week-old pigs by the use of twenty one biotinylated-labelled lectins with avidin-biotin-peroxidase complex method. Piglets with experimental group were inoculated by feeding 5 ml of culture inoculum (5 × 10+ colony-forming units/ml) with 15 ml of milk replacer. At the onset of diarrhea, experimental piglets and time-matched control piglets were euthanatized using electrocution, necropsied, and tested by lectin histochemistry. As compared with control, staining intensity of seven lectins altered in ileal villus brush border and goblet cells of pigs inoculated with the pathogen.
A 3-year-old female ferret died five days after admission to a veterinary clinic for treatment of acute dyspnea and posterior paresis. Blood chemistry showed no hypergammaglobulinemia. Histopathological examination revealed mild to severe inflammatory infiltrates, composed mostly of plasma cells, in multiple organs. Lesions were especially severe in the kidneys, where focal segmental membranous glomerulopathy was also present. In the liver, in addition to lymphocytic and plasmacytic infiltration in periportal areas, dilatation and proliferation of the bile ducts were seen. On analysis of PCR products, using primers directed against the gene encoding Aleutian disease (AD) viral capsid and formalin-fixed kidney samples, we detected a single band of about 400 bp, specific to the AD virus.
The minimum inhibitory concentration (MIC) was measured to evaluate the antibacterial activities of chloramphenicol (CP), thiamphenicol (TP) and florfenicol (FFC) against the aquatic bacterial isolates from soft-shell turtles, fish and shellfish. Amoxicillin (AMPC), oxytetracycline (OTC) and oxolinic acid (OA) were included to compare with above protein synthesis inhibitors. The results showed that the order of MIC range of the isolates from soft-shell turtles for tested drugs was OA>FFC, CP>TP>AMPC, OTC. The percentage of the resistant strains indicated that OA was the lowest (7.14%) and OTC was the highest (85.07%). The order of antibacterial activity against the isolates from fish was OA>FFC>CP >AMPC>OTC>TP. The percentage of the resistant strains revealed that OA (13.64%) and OTC (80.91%) were the lowest and the highest, respectively. For the isolates from shellfish, the order of antimicrobial activity was OA>CP, FFC>AMPC, OTC, TP. TP showed the greatest percentage of the resistant strains (58.7%), but that of OA was the lowest (4.35%). The most common resistant patterns of the isolates from turtles, fish and shellfish were AMPC-OTC, CP-TP-AMPC-OTC, and FFC-CP-TP-AMPC-OTC, respectively. There were partially-complete resistance of the resistant isolates among CP, TP and FFC. The findings indicated that previous treatment might affect the choice of drug to use for aquatic bacterial diseases.
We studied the effects of TAK-044, a nonselective endothelin (ET) receptor antagonist, on the indomethacin- or methylene blue-induced constriction of the ductus arteriosus (DA) in rats and compared them with the effects on spontaneous DA constriction. Injection of TAK-044 into 21-day-old fetuses in utero was performed through the uterine wall of laparotomized mother rats under light ether anesthesia. The fetuses were autopsied 3 hr after treatment with TAK-044 (10 mg/kg) in utero and simultaneous administration to the laparotomized mother rats of indomethacin (3 mg/kg, po) or methylene blue (100 mg/kg, ip). In the second experiment, pregnant rats were decapitated on day 21 of gestation to obtain newborn rats by cesarean delivery. Newborn rats which were given TAK-044 (2, 10 mg/kg) immediately after or 1 hr before cesarean delivery were autopsied at various times after birth. In both experiments, pups were rapidly frozen in an acetone-dry ice mixture at autopsy to evaluate the DA constriction by the whole-body freezing and shaving method. TAK-044 injection into the fetus 3 hr before autopsy completely inhibited the DA constriction induced by maternal treatment with indomethacin or methylene blue. TAK-044 caused dose-dependent inhibition of the spontaneous closure of the DA after birth. The inhibitory effect was more pronounced in pups which were given TAK-044 in utero 1 hr before birth; however, the inhibitory effect was incomplete in newborn pups. These results, together with the previous finding that BQ-123, an ETA-specific receptor antagonist, inhibits the ductal constriction induced by oxygen in vitro [Coceani et al., 1992], indicate that the ETA receptor plays a significant role in the indomethacin- or methylene blue-induced DA constriction as well as in the spontaneous DA constriction after birth, and also indicate that the inhibition of ETA receptor by TAK-044 was more easily achieved in fetuses than in neonates.
Botulinum C3 enzyme produced by Clostridium botulinum type C and D strains modifies Rho proteins. In a previous study, we observed that the LDH isozyme pattern of neurons treated with C3 enzyme was different from that induced with endogenous growth factor of neurons such as NGF . This type of change is considered to have an advantage in the medical use of C3 enzyme for neural disorder. To determine the functional similarity of C3-treated neurons to control and NGF-treated neurons, we examined the responses of C3-treated neurons to various drugs, including some neurotransmitters, by measuring the rise of intracellular Ca ions into the neurons. The time course of the rise of intracellular Ca ions induced by high concentration of potassium in the C3-treated neurons was similar to that in the NGF-treated neurons. The C3-treated neurons responded to glutamic acid, aspartic acid, kainic acid, γ-aminobutylic acid, muscarine and ACh with similar time courses and magnitudes as the control neurons. These results suggest that the C3 enzyme induces the functional differentiation of neurons, and that C3 enzyme has the potential for the medical use as an exogenous differentiation-inducing factor of neurons.
We reviewed records of all outbreaks of food-borne illnesses due to schoollunch in Japan from 1987 through 1996 to determine the risk factors causing these outbreaks. Major hazards in 269 outbreaks were Salmonella spp., Campylobacter jejuni, Escherichia coli and Stapylococcus aureus. Foods including uncooked or partially cooked items, salad or egg products presented a high risk in 62 outbreaks with confirmed food sources. Contaminated food items were involved in 29 incidents (46.8%); storage of foods for an extended period before serving in 29 incidents (46.8%), inadequate cooking and cross contamination in 21 incidents (33.9%) each; infected employees in nine incidents (14.5%).
Apoptotic cell death in the testes of 4 dogs with azoospermia was examined. Blood plasma luteinizing hormone (LH), testosterone (T), and estradiol-17β (E2) concentrations, and testicular transferrin (Tf) concentration as a marker of Sertoli cell function were measured in the 4 azoospermic dogs and in 5 normal dogs. The spermatids in 2 of the 4 azoospermic dogs and the Leydig cells in 3 of them exhibited apoptotic cell death. Mean LH, E2, and Tf concentrations in the 4 azoospermic dogs were significantly higher than in the normal dogs (P<0.01). These findings suggested that the azoospermia in all 4 dogs might has been caused by abnormal functions of Sertoli cells as well as Leydig cells.
Because of weak resistance of canine sperm to freezing, an applicable method of preparing canine frozen semen has not yet been established. We added various concentrations of Orvus ES Paste (OEP) to egg yolk Tris-fructose citrate, and investigated its effectiveness on survival of spermatozoa. Addition of 0.5-1.0% OEP to the extender for freezing canine semen was effective in prolonging post-thaw survival of spermatozoa.
Using the triple-stain technique, we investigated whether sperm acrosomes in frozen canine semen were protected during freezing and thawing by addition of a surfactant, Orvus ES Paste (OEP), to the extender. Acrosomes were clearly shown to be protected by the addition of OEP to the entender when compared with those in sperm frozen without OEP addition (p<0.05).
We previously reported that D0870 induced QT prolongation and sudden death due to torsades de pointes (TdP) in dogs and that catecholamines played an important part in the development of the sudden death. In the present study, we analyzed in detail the ambulatory electrocardiographic recordings obtained from the just-mentioned study to elucidate the mechanism of the onset of TdPs and conducted an in vitro study using isolated canine Purkinje fibers to assess the effect of D0870 on repolarization. The hearts with TdPs observed before the sudden death showed a higher sinus rate for 5 and 10 sec before the onset, a shorter coupling interval, and a higher ventricular tachycardia rate compared with those having the non-sustained TdPs. These findings suggest that D0870-induced fatal TdPs may be provoked by a triggered activity developed from delayed after depolarizations. In contrast, as the pause-dependent, non-sustained TdPs in bradycardia showed a typical “short-long-short” sequence, they may be developed from early afterdepolarization . Moreover, the results of the in vitro study supported our contention that D0870 induced QT prolongation in a reverse use-dependent manner in vivo and suggested that it may inhibit not only rapidly activating delayed rectifier potassium current (Ikr) but also L-type Ca current (ICa-L).
The inhibitory activities of various 8-difluoromethoxy-4-quinolone derivatives against feline immunodeficiency virus (FIV) replication in the chronically infected cell line P-CrFK were investigated. Certain derivatives were found to inhibit FIV production from P-CrFK cells in a dose-dependent manner without exhibiting cytotoxic effects at inhibitory concentrations. Based on this study, the structures important for anti-FIV activity are suggested to be (i) a carboxyl group at position C-3, and (ii) an aromatic modification at position 4 of the C-7 piperazinyl moiety.