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In vitro mechanical properties of equine tendons in relation to cross-sectional area and collagen content 总被引：3，自引：0，他引：3
The mechanical properties of the deep digital flexor tendon (DDFT), the superficial digital flexor tendon (SDFT) and the suspensory ligament (SL) of the hindlimb of the horse were studied in vitro. The tendons were observed at several morphologically distinct sites. The loaded tendon is homogeneously strained, in spite of large variations in cross-sectional area. Consequently the modulus of elasticity was inversely proportional to the corresponding cross-sectional area and ranged from 738 MPa (megaPascal, N mm-2) to 1398 MPa within the DDFT, from 1000 MPa to 1282 MPa within the SDFT and from 576 MPa to 669 MPa within the SL. The collagen content was inversely proportional to the cross-sectional area and proportional to the modulus of elasticity. This stresses the influence of tendon composition on the mechanical properties, and also demonstrates the difficulty in judging the strength of a particular tendon or site within a tendon from its cross-sectional area. The respective tendons ruptured at strains of 10.0 per cent (DDFT), 12.3 per cent (SDFT) and 11.0 per cent (SL). The influence of strain rate on the modulus of elasticity is small, and these tendons may therefore be considered as non-linear elastic structures. The average hysteresis is about 5 per cent. 相似文献
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The present study was undertaken to determine the influence of the peroneus tertius muscle on the loading regime of the tibia in the horse. Strain gauge rosettes were bonded to the cranial and caudal cortices of the left and right tibiae in six Shetland ponies. In vivo bone strain recordings were made before and after unilateral transection of the peroneus tertius muscle. Relatively large individual variations in response to transection were observed in both the experimental and the contralateral control limbs. The principal strain values on the cranial and caudal cortices increased during the second peak in the support phase by approximately 10 per cent; the angle between the larger principal strains and the long axis of the bone, measured proximal to the gauges, rotated approximately 4 degrees medially in experimental limbs, but did not change in the control limbs. It seems unlikely that the peroneus tertius muscle has a substantial influence on the loading regime of the tibia during normal walking. 相似文献
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Disease of geese caused by a new herpesvirus 总被引：3，自引：0，他引：3
PJ KETTERER BJ RODWELL HA WESTBURY† PT HOOPER† AR MACKENZIE‡ JG DINGLE§ HC PRIOR 《Australian veterinary journal》1990,67(12):446-448
A goose flock farmed outdoors in south-eastern Queensland suffered an outbreak of peracute disease with high death rate (97%). Small button ulcers and large plaques overlying lymphocyte aggregates were present on the mucosa of the small intestine of affected birds. Small white foci of necrosis and focal haemorrhages were seen in the livers. Numerous intranuclear inclusion bodies were observed microscopically in hepatocytes and a herpesvirus which grew rapidly in chicken kidney cells was isolated from tissues. Duck virus enteritis (DVE) was suspected but DVE antiserums failed to neutralise the virus. Further serological studies with a limited range of known avian herpesviruses have failed to identify the virus. Experimental transmission resulted in high mortality in geese (100%), lower mortality in ducklings and nil mortality in chickens. Surveillance studies showed no evidence of infection in domestic and wild birds beyond the original farm and the infection appears not to have been established in the area. Wild ducks, which were frequent visitors to the farm dam, were considered the most likely source of the infection. 相似文献
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The ground reaction force patterns from 20 clinically sound Dutch Warmblood horses (Group A) were recorded at the normal walk. The data from four to 10 stance phases of each limb were computer averaged after normalisation to the animal's body mass and to the stance time. This analysis method allowed comparison of data from left and right fore- and hindlimbs within and between horses. The left-to-right symmetry in the reaction force peaks of contralateral limbs of one horse exceeded 90 per cent. The time in the stance phase at which the peaks occur were even more symmetrically distributed. A characteristic force-force diagram was constructed by plotting the longitudinal horizontal and the vertical ground reaction forces against each other; in this way the symmetry of loading of contralateral fore- and hindlimbs could be interpreted easily. Force plate tracings were obtained from eight horses (Group B) in three successive years. The similarity of the tracings from a sound, well-trained horse over that period was better than the differences between horses of the same breed. 相似文献
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Distribution of ground reaction forces of the concurrently loaded limbs of the Dutch Warmblood horse at the normal walk 总被引：1，自引：0，他引：1
The distribution of the ground reaction forces (GRF) over the concurrently loaded limbs of the normally walking horse was determined from 'representative' GRF patterns of all limbs, which were plotted in correct time order after analysis of simultaneously taken high-speed film. This procedure visualises the GRF patterns of each of the four limbs in relation to the GRF pattern(s) of the one or two concurrently loaded limb(s) during a complete stride. In 15 clinically sound horses the mean averaged GRF data and temporal stride parameters showed an almost complete symmetry between both the forelimbs and both the hindlimbs and resulted in a load distribution during the first half of the stride being almost identical to those in the second half of the stride. The transverse horizontal force (Fx) was maximum during the unilateral support phase. No more than one limb at a time contributed to either the deceleration or acceleration longitudinal horizontal (Fy) force. The total vertical (Fz) force of the concurrently loaded limbs during a complete stride fluctuated between 7 to 12 N/kg body weight. In a left forelimb lame horse, the decreased GRF amplitudes were compensated by increased GRF amplitudes in the three other limbs during both the swing phase and stance phase of the lame limb. Due to alterations of both GRF data and temporal stride parameters of the lame limb, as well as the three other limbs, the distribution of the GRF during the complete stride was changed dramatically. 相似文献
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The amplitudes, impulses and times of occurrence of a number of selected peaks in the ground reaction force tracings of 17 horses with various clinical histories were compared with those of 20 horses used to establish values for the 'standard' Dutch Warmblood horse. The resulting factors were combined, using different weighting factors, into indices characterising each limb. The symmetry between the loading of the forelimbs and the hindlimbs was used to calculate amplitude and peak-time symmetry indices. Limb and symmetry indices were combined in one H(orse) INDEX. This method of quantifying the ground reaction force pattern, together with appropriate graphic display of the tracings, was useful in clinical evaluation of force plate measurements. 相似文献
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甘蓝型油菜(Brassica napus)无花瓣突变体“ Ap-Tengbe ”花瓣性状的遗传规律 总被引：2，自引：0，他引：2
本项研究旨在探明甘蓝型油菜突变体Ａｐ－Ｔｅｎｇｂｅ无花瓣性状的遗传规律,‘Ａｐ－Ｔｅｎｇｂｅ’和德国栽培品种‘Ｆａｌｃｏｎ’之间通过正反交产生两个方向的Ｆ１,ＢＣ１－１（Ｆ１和‘Ａｐ－Ｔｅｎｇｅｂｅ’之间）,ＢＣ１－２（Ｆ１和‘Ｆａｌｃｏｎ’之间）以及Ｆ２各遗传群体,根据田间各遗传群体ＰＤｇｒ（花瓣度）的观察和统计,作者提出‘Ａｐ－Ｔｅｎｇｅ’突变体无花瓣性状的遗传由细胞质和两对核隐性基因共同控制 相似文献
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