Fifteen and eight mature beagles, without (normal group) and with experimental mitral regurgitation (MR group), respectively, were given 0.02 mg/kg/day digoxin powder for 10 days orally. The optimum time for sample collection after administration of digoxin was observed to be 8-18 hr and 10-22 hr in the normal and MR groups, respectively. In both groups, a stable concentration was reached after 3-5 days of treatment. No differences in plasma level were observed between sexes. The optimum concentration of digoxin was attained at an earlier stage than has been previously reported for both dogs and humans. 相似文献
This study was undertaken to quantify the relationships between the rate of ammonia excretion by brine shrimp and dry weight (body size) and food density. Measurements of the rate of ammonia excretion of the brine shrimp were made at 25 C in darkness. Under these conditions, the excretion rate of ammonium-nitrogen can be generalized as a function of body weight and food (Nannochloropsis sp.) density. The relationship between the body weight (W) and excretion rate of ammonium nitrogen (EN) is expressed as EN=α Wγ, where α is the metabolic level. The parameter α is dependent on ration, such that α=αo±αr where αo= metabolic level in starvation and αr= the metabolic level which increased with feeding or changed with the food density. In experiments in which the animal starved, the equation above becomes EN=αoWγ, and the values of α and γ were 0.22 and 0.93, respectively. The rate of ammonium excretion rose from 5.42 × 10?4 to 2.28 × 10?1μg N/animal/h as dry weight measured from 1.57 × 10?3? 1.04 mg dry weight per animal. Next, it is convenient to express αr as αr=αfmax= (1 ? 10?kc), where αfmax is the maximum rate of αf at saturated level of food density, C is the mean cell density, and k is a constant defining the rate of change of the metabolic rate with cell density. Therefore, the rate of ammonia excretion by brine shrimp could be expressed as EN=αo [1 ? a(l ? 10?kC)]Wγ, and a =αfmax/αo. The values of the kinetics parameters obtained from experiments where shrimp were fed were a = 2.3 and k = 0.15×10?7. Consequently, the maximum rate of ammonia excretion at a saturated food density is equivalent to 3.3 times the rate of animals that are not fed. 相似文献
1. One hundred and seven laying hens were hypophysec‐tomised to clarify the relationship between hypophysectomy and the effect of progesterone (P4) on ovulation.
2. Hens were hypophysectomised at 6 intervals from 4.5 to 11.0 h before the expected time of ovulation. Ovulation occurred in the hens operated on from 4.5 to 7.3 h, but did not take place in birds operated on from 9.2 to 9.8 h before the expected time of ovulation.
3. When a single dose of P4 (2 mg/hen) was injected iv immediately after the removal of the anterior pituitary from 7.5 to 9.8 h before the expected time of ovulation, ovulation was induced. However, the percentage of hens responding decreased in proportion to the lapse of time between the hypophysectomy and the expected time of ovulation. No ovulation was induced in hens which were hypophysectomized and given P4 10.2 to 11.0 h before the expected time of ovulation.
4. It is suggested that ovulation is induced by P4 alone possibly in the absence of preovulatory gonadotrophins and that P4 acts directly on the ovary to induce follicle rupture. 相似文献
Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of
bamboo plants. The symptoms of this disease are believed to be induced by plant
hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in
cultures of this fungus in an l-tryptophan-supplemented liquid medium.
IAA production was confirmed on 30 isolates of A. take from various
hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of
IAA in A. take culture was examined by analyzing intermediate products
and by feeding experiments. The results showed that the indole-3-pyruvic acid
pathway (l-tryptophan → indole-3-pyruvic acid → indole
acetaldehyde → IAA) was the dominant pathway in A. take.
Received: June 3, 2002 / Accepted: July 25, 2002 相似文献
Slow-reacting complement-requiring neutralizing (NT) antibody was detected in sera from cattle 2 weeks after infection with Akabane virus. Bovine sera obtained 3 or 4 weeks after infection contained slow-reacting noncomplement-requiring NT antibody. The slow-reacting complement-requiring NT antibody was sensitive to 2-mercaptoethanol (2-ME), whereas the slow-reacting noncomplement-requiring NT antibody was resistant to 2-ME. The initial phase may represent the IgM response and the later phase a change to IgG. A NT test was developed in which virus-serum mixtures were incubated at 4 degrees C for 48 h and then with complement at 37 degrees C for 60 min; this gave an improved sensitivity over the previous incubation at 37 degrees C for 60 min. 相似文献
The pathological effects of copper deficiency (COD) are well known. However, the pathogenesis of cardiomyopathy resulting from COD remains unclear. In this study, aimed to elucidate the pathogenesis of COD-induced cardiomyopathy by examining the morphology of the cardiovascular system in copper-deficient rats using histopathology, immunohistochemistry, and scanning and transmission electron microscopy. Changes detected in the myocardium and interstitium were consistent with those reported for COD. Morphological changes included mesh-like changes in the capillary endothelial cells that appear to be a novel finding in COD-induced cardiomyopathy. These changes are hypothesized to result from abnormal vascular remodeling following damage to the basement membrane and due to the mechanical effects of myocardial contractions. Although cardiomyopathy may be associated with microcirculatory disorders arising from these lesions, further investigations are necessary to demonstrate a causal relationship between the pathogenesis of cardiomyopathy and the contribution of these lesions to disease progression. 相似文献
Farm managers' decision to cull dairy cows is based on the cows' milk production, history of disorder(s), and reproductive performance, each of which affects dairy cows' lifetime (herd life and productive lifespan). We investigated the relationships among the incidence of clinical mastitis (CM), the reproductive performance, and the culling rate. We also assessed the effects of these relationships on the lifetimes of dairy cows, using the records made before and after the introduction of an automatic milking system (AMS) at Hiroshima University Farm. Milk yield, CM incidence density, and culling rate of dairy cows increased after the AMS introduction. The CM incidence was associated with an elongation of the calving interval in cows with the same parity. CM in the 1st parity might have caused the reductions of the cows' lifetime and their parity at culling. A higher age at first calving (AFC) was associated with an increase in culling rate but did not lead to a significant decrease in lifetime. Investigations of the factors mediating CM in the 1st parity or AFC with CM incidence or culling rate in the later stages might contribute to the control of lifetime of dairy cows. 相似文献
In south‐western Japan, centipedegrass (Eremochloa ophiuroides; CG) offers a novel option for a warm‐season perennial for grazing use in areas where bahiagrass (Paspalum notatum; BG) can be grown. However, the potential of CG as a forage has not been fully explored because of the short history as a forage crop. We conducted four experiments to evaluate CG (cv. TifBlair) in comparison with BG (cv. Pensacola) in terms of sward characteristics, nutritive value and choice by animals. In each experiment, four Japanese Black cows (Bos taurus) were individually allowed to graze conterminous monocultures of CG and BG (5 × 10 m each) for 30 min. Irrespective of regrowth durations and fertilizer rates, CG was consistently shorter, leafier and denser, contained lower acid detergent fiber and cellulose, and was preferred or equally selected by cows, as compared with BG. Furthermore, CG maintained sufficient levels of crude protein (80–89 g/kg DM) to ensure voluntary intake of ruminant animals under extended regrowth? and without fertilizer, whereas BG failed to do so (65 g/kg DM). CG provided higher digestible dry matter than BG when crude protein concentration exceeded 86 g/kg DM. The results indicate advantages of CG as a forage. 相似文献
Porcine bioprosthetic valves cross-linked with glutaraldehyde and polyepoxy compound were newly developed for mitral valve replacement (MVR) in dogs. Five beagle dogs were performed a left thoracotomy and underwent MVR using the porcine bioprosthetic valves during cardiopulmonary bypass (CPB). A vein catheter inserted into right atrium and a vent catheter inserted into the right ventricle to drain. The hemodynamic conditions of CPB were excellent during surgery. The left atrial pressure was measured before and after MVR; there was no significant difference and it was normal. Thrombosis and the prosthetic valve regurgitation were not observed one week after MVR. Pressure half time (PHT) prolonged significantly (P<0.05) from 31.40 +/- 4.0 msec presurgery to 99.20 +/- 19.4 msec at seven days after MVR, although it indicated the normal range as the bioprosthetic valve. The symptom of the prosthetic valve failure was not observed. This study indicated that the MVR using porcine bioprosthetic valves under CPB might have been effective in dogs as a short-term evaluation. 相似文献