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Biomedical subjects

S R Duff

Publications and source records attributed to S R Duff.

At least 19 recordsLinked to original sources
PubMed2004

Nanometre localization of single ReAsH molecules.

ReAsH is a red-emitting dye that binds to the unique sequence Cys-Cys-Xaa-Xaa-Cys-Cys (where Xaa is a noncysteine amino acid) in the protein. We attached a single ReAsH to a calmodulin with an inserted tetracysteine motif and immobilized individual calmodulins to a glass surface at low density. Total internal reflection fluorescence microscopy was used to image individual ReAsH molecules. We determined the centre of the distribution of photons in the image of a single molecule in order to determine the position of the dye within 5 nm precision and with an image integration time of 0.5 s. The photostability of ReAsH was also characterized and observation times ranging from several seconds to over a minute were observed. We found that 2-mercaptoethanesulphonic acid increased the number of collected photons from ReAsH molecules by a factor of two. Individual ReAsH molecules were then moved via a nanometric stage in 25 or 40 nm steps, either at a constant rate or at a Poisson-distributed rate. Individual steps were clearly seen, indicating that the observation of translational motion on this scale, which is relevant for many biomolecular motors, is possible with ReAsH.

Amino Acid Sequence↗
PubMed1992

Effects of age, sex and housing on the trabecular bone of laying strain domestic fowl.

To determine the effects of age, sex and housing on trabecular bone volume, samples were collected from groups of male and female domestic fowl housed in cages or floor pens from four to 60 weeks old. Between 25 and 60 weeks old, trabecular bone volume decreased by 25 per cent in sections of free thoracic vertebrae (T5) from female birds, the loss occurring at an earlier age in caged birds. Over the sample period, TBV in male caged birds diminished by 35 percent, but male floor birds showed no reduction in trabecular bone volume. At 60 weeks, trabecular bone volume was 30 per cent greater in male caged birds and 40 per cent greater in male floor birds than in the corresponding females. In reproductively active females, no trabecular osteoid was observed, indicating no new trabecular bone formation. However, trabecular osteoid was present in two birds aged 60 weeks which had regressed ovaries. Osteomalacia was not seen in any of the bone samples.

Aging↗
PubMed1991

Assessment of pain associated with degenerative hip disorders in adult male turkeys.

The extent to which degenerative hip disorders in adult male turkeys result in pain was investigated in a two-period crossover experiment. The birds in six pens received daily injections of an anti-inflammatory steroid (betamethasone) during week 1 and control injections of physiological saline in week 3. The turkeys in the other six pens received saline in week 1 and steroid in week 3. Behavioural observations of the birds during weeks 1 and 3 revealed that the steroid treatment resulted in more spontaneous activity. The steroid-treated birds also showed speedier movement in a sexual activity test in weeks 1 and 3. Post mortem examination revealed that all the turkeys were suffering from degenerative hip disorders. It is concluded that degenerative hip disorders in adult male turkeys result in a state of chronic pain which inhibits spontaneous activity and sexual activity.

Animals↗
PubMed1991

Effects of vitamin or mineral deficiency on the morphology of medullary bone in laying hens.

Adult laying hens were fed diets deficient in phosphorus, calcium, calcium and phosphorus, and vitamin D3 to determine their effects on bone histology and parathyroid gland size. The phosphorus deficient diet caused an insignificant decrease in parathyroid size while the other diets caused significant increases. A considerable amount of individual variation in medullary bone volume and osteoid seam width was observed in all groups but, despite this, the calcium, calcium and phosphorus and vitamin D3 deficient diets clearly resulted in increased osteoid. Birds receiving diets deficient in calcium and phosphorus, and in vitamin D3 for longer periods were observed to have partially or completely resorbed medullary bone. Osteodystrophia fibrosa was noted in vitamin D3 deficient birds which had no follicular activity.

Animals↗
PubMed1991

Hydrogenated oil decreases tissue concentrations of n-6 polyunsaturated fatty acids and may contribute to dyschondroplasia in broilers.

1. In a factorial design of dietary treatments, male Ross broilers were given diets containing soyabean oil, hydrogenated soyabean oil (as a source of trans-fatty acids) or feed fat with either 0 or 300 micrograms of added D-biotin/kg. 2. Growth to 28 d was not influenced by the dietary treatments. 3. Length of tibiotarsal bones was reduced (P less than 0.05) and severity of leg bone cartilage lesions, characteristic of dyschondroplasia, was highest (P less than 0.05) in broilers fed on diets containing hydrogenated soyabean oil. 4. Feeding hydrogenated soyabean oil lowered (P less than 0.05) the concentrations of C20:4n6 and the ratios of C20:4n6/C18:2n6 in liver and growth plate cartilage. 5. Growth plate cartilage from birds affected with dyschondroplasia contained lower proportions of prostaglandin precursor fatty acids compared with normal growth plate. 6. It is speculated that an inhibition of prostaglandin biosynthesis brought about by the presence of trans-fatty acids might contribute to the occurrence of lesions similar to dyschondroplasia.

Animal Feed↗
PubMed1990

Morphology of medullary bone during the egg formation cycle.

The medullary bone of birds is known to function as a calcium store for egg shell production, but it is not known if the stage of shell formation within the egg formation cycle is reflected by the thickness of osteoid seams on the medullary bone. Adult laying hens were killed at two points in the formation cycle to determine the effects of shell formation on medullary bone using histological techniques. No differences in medullary bone volume or osteoid thickness were apparent at either of the two points. Fluorochrome bone labelling techniques demonstrated, however, that less medullary bone mineralisation occurred during the active period of shell formation.

Animals↗
PubMed1989

Disturbed endochondral ossification in the axial skeleton of young broiler fowls.

Physeal lesions have been studied in thoracic vertebrae (T3, T4 and T5) of 51 broiler fowls between 28 and 53 days old. Vascular perfusion studies performed on 10 birds confirmed that the cartilaginous epiphyses of T3, T4 and T5 were essentially avascular and thus differ from those of the major long bones. Findings confirm the observation that a number of morphologically distinct lesions of osteochondrosis occur in broiler fowls and that, when physeal clefts can be implicated in their aetiology, the term "osteochondrosis" is inappropriate. Although the location of clefts often differs in long bone and vertebral physes, when metaphyseal vessels are disrupted, the end-result on endochondral ossification is the same in both the axial and appendicular skeleton. Other lesions were observed both independently and in association with osteochondrosis. Such lesions include necrotic seams devoid of haemorrhage, acellular foci and chondrolysis, all of which were most frequently observed in the same vertebral end-plates. Because osteochondrosis was also most common in the same vertebral end-plates, a common aetiology is suggested. Surface regressive changes were common in the articular cartilage of T3, T4 and T5, and it is noteworthy that such changes, although common in older birds, are present in birds so young.

Animals↗
PubMed1989

Physeal clefts and disturbed endochondral ossification in broiler fowls.

Histopathological studies have been conducted on 35 physes from 19 broiler type fowls of different ages in order to elucidate the pathogenesis of dyschondroplasias. Findings support the suggestion that different forms of dyschondroplasia occur in broiler fowls and that histopathological studies are required if each is to be distinguished. It is concluded that physeal clefts produce one form of dyschondroplasia when epiphyseal blood vessels are occluded. A unifying concept is proposed that implicates epiphyseal and/or metaphyseal vascular disturbances in the differing morphology of some lesions, at least. This concept is supported by findings in this and other studies and is proposed as a possible explanation for morphological differences between avian dyschondroplasia and mammalian osteochondrosis.

Animals↗
PubMed1989

Musculo-skeletal lesions in adult male broiler breeder fowls and their relationships with body weight and fertility at 60 weeks of age.

1. Males from three broiler breeder experiments were examined to determine the incidence of musculo-skeletal lesions (destructive cartilage loss, dyschondroplasia and its sequelae, ruptured tendons and ligaments) in birds culled for low fertility and in males surviving to the end of the breeding period. Relationships with body weight and fertility were studied. 2. The incidence of musculo-skeletal lesions in males culled for low fertility was high. 3. In two experiments, high body weights at termination of the breeding period were associated with a raised incidence of musculo-skeletal lesions and lowered fertility. 4. The results support the hypothesis that lack of control of male body weight gain per se is an important cause of declining fertility with age in broiler breeder flocks. There was no evidence that males were obese.

Aging↗
PubMed1988

Avulsion of the patellar ligament in osteopenic laying fowl.

Metabolic bone disease in laying fowl has been associated with mortality and decreases in egg production. Recently there appears to have been an increasing incidence of the disease and the affected flocks have shown a variable response to dietary treatments. In 14 birds from eight recent submissions, avulsion of the patellar ligament together with part of its bony insertion was observed. Because the skeletons of the affected birds were judged from radiographs to be osteopenic, the lesions were probably pathological fractures. Histopathological studies of four birds revealed osteoporosis affecting cancellous bone trabeculae; in one bird, however, the medullary bone trabeculae were largely composed of unmineralized or poorly mineralised matrix, a finding which can be interpreted as osteomalacia.

Animals↗
PubMed1988

Further studies on collateral ligaments of knee and intertarsal joints in domestic fowl.

Collateral ligament attachments in distal femora and distal tibiotarsi were examined in broilers on ad libitum and restricted feeding and in laying strain fowls fed ad libitum. Histopathological studies revealed morphological changes in ligaments of ad libitum-fed broilers which were less apparent or absent in other birds examined. One such change was loss of crimp pattern in collagen bundles of ligaments, which suggested that structural derangement had occurred. Chondroid metaplasia and foci of hyaline cartilage were observed in ligaments of ad libitum-fed broilers and may result from tissue ischaemia. Similarities were noted between ligament attachments in broilers and Osgood-Schlatter disease in man; lesions in broilers may well have a similar aetiology. It is concluded that although feed restriction restores some semblance of normality in broiler ligaments, the propensity for abnormality remains and becomes apparent in heavier birds. Such reasoning casts doubt on the wisdom of modern broiler breeding practice where feed restriction can mask genotypic predisposition to clinical disease.

Animal Husbandry↗
PubMed1988

Effect of exercise on the vascular pattern in the bone extremities of broiler fowl.

The vascular morphology of the proximal femur, tibiotarsus and tarsometatarsus was studied in growing broiler chicks. A carousel was used to exercise one group of 24 birds for four periods of 15 minutes each day. A second group (controls) were not exercised. Some birds were killed during the course of the experiment, and the remainder after 25 days of exercise when they were 33 days old. After killing the limbs were perfused and the bone extremities cleared. The bone extremities were then cut into 1 mm thick slabs and examined. There were abnormalities of the physis and physeal vasculature in 18 (25 per cent) of the bone extremities from the exercised birds and in 24 (40 per cent) of the bone extremities from the unexercised (control) birds. The low level of activity in the unexercised fowls of the present study appeared to contribute to these abnormalities.

Animals↗
PubMed1988

Effect of unilateral weight-bearing on pelvic limb development in broiler fowls: vascular studies.

Fifteen broiler fowls which habitually adopted a unilateral weight bearing stance were studied. In the majority of fowls the left pelvic limb was weight bearing and the right limb showed severe angular deformity. Dyschondroplasia occurred most frequently in the load-bearing limb. In the load-bearing limb the majority of lesions were in the femur and proximal tibiotarsus. In the non-load-bearing limb lesions most frequently occurred in the bone extremities of the distal tibiotarsus and proximal tarsometatarsus. Occluded epiphyseal vascular canals occurred in conjunction with physeal thickening at some dyschondroplastic sites. The majority of dyschondroplastic lesions contained elongated penetrating epiphyseal vessels and vessels derived from the perichondrial ring. These vessels were associated with chondrocyte hypertrophy and matrix calcification, which was considered to lead to the repair of the lesions. There was minimal calcification of cartilage at the base of the dyschondroplastic lesions and the underlying metaphyseal vessels were blunt ending. This suggested that a band of abnormal physeal cartilage was acting as a barrier to penetration by the metaphyseal vessels and so preventing subsequent endochondral ossification.

Animals↗
PubMed1987

Meniscal lesions in knee joints of broiler fowls.

Post-mortem examination of the knee joints of 28 broiler type fowls revealed abnormalities in one or both medial menisci. Certain abnormalities appeared to be associated with knee ligament disruption. These included torn or frayed menisci and those which were displaced, usually in a mesial direction. Histopathological studies revealed that each of these abnormalities was normally associated with degenerative meniscal lesions. Other meniscal abnormalities showed no association with knee ligament disruption. Such menisci can be regarded as being of aberrant shape and most commonly the medial meniscus was enlarged and "discoid". Discoid medial menisci frequently showed histological abnormalities. As in other species, it is suggested that discoid menisci are predisposed to injury probably because of their larger contact area.

Animals↗
PubMed1987

Destructive cartilage loss in the joints of adult male broiler breeding fowls.

Patterns of destructive cartilage loss were studied in 60 male broiler breeding fowls. All showed destructive lesions in their hip or intertarsal joints and were between 18 and 62 weeks old when killed. Although surface regressive changes in articular cartilage were common, deep fibrillation, as seen in human and mammalian osteoarthrosis, was not identified. This difference probably reflects the more fibrous nature of articular cartilage in birds, but a number of similarities to hyaline cartilage degeneration were noted. Destructive cartilage loss resulted from partial or full thickness detachment of uncalcified cartilage. Clefts in deep cartilage preceded segmental detachment and occurred in cartilage with an intact articular surface. Detachment of segments of uncalcified cartilage may be the principal method of destructive cartilage loss in all avian species. It is concluded that clefts and destructive cartilage loss in adult broiler fowls can be a consequence of articular osteochondrosis or may result from osteoarthrosic lesions.

Acetabulum↗
PubMed1987

Thinning of articular cartilage in the domestic fowl.

Thinning of articular cartilage was identified in pelvic limb joints of broiler and Leghorn-type fowls. Almost all of 100 fowls examined showed cartilage thinning or loss in hip and knee joints. Particular attention was paid to proximal femora; in these, the principal mechanism of cartilage loss involved processes described as "peripheral remodelling". From the edge of cartilage sheets, fibrovascular tissue removed articular cartilage by two mechanisms. Either a pannus of fibrovascular tissue covered the articular surface or non-osseous tissue invaded through discontinuities in the bone plate. As in man, peripheral remodelling appears to be age-related and unrelated to regressive or destructive cartilage loss.

Animals↗
PubMed1987

Skeletal changes in broiler chicks and turkey poults fed diets containing ochratoxin A.

Broiler chicks and turkey poults were divided at hatching into experimental and control groups. Experimental birds were fed a diet contaminated with 4 ppm ochratoxin A, whereas the ration of control birds was confirmed to be mycotoxin free. Birds were killed at fortnightly intervals up to 10 weeks old and skeletal changes were investigated. Almost all experimental birds developed generalised skeletal osteopenia with disturbed endochondral and intramembranous bone formation. Histological changes in diaphyseal cortices could account for the reduced breaking strength of bones from birds fed mycotoxin, which have been reported by others. One bird showed changes consistent with a diagnosis of hypophosphataemic rickets. In others, however, osteoid formation was defective and changes were interpreted as osteoporosis. Although it might be tempting to suggest that osteoporosis is a result of a direct toxic effect of ochratoxin on osteoblasts, the effect of inanition, inactivity and general debility may be equally important.

Animals↗