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Biomedical subjects

C M Dwyer

Publications and source records attributed to C M Dwyer.

At least 19 recordsLinked to original sources
PubMed2006

Maintenance of body temperature in the neonatal lamb: effects of breed, birth weight, and litter size.

To survive, the newborn lamb must be able to maintain body temperature and to stand and move to the udder to suck colostrum to fuel heat production. The objective of this study was to investigate whether neonatal lambs showing slow behavioral progress to standing and sucking also have an impaired ability to maintain body temperature. The time taken to stand and suck after birth, rectal temperatures, and blood samples were collected from 115 newborn single, twin, and triplet lambs of 2 breeds, Scottish Blackface and Suffolk, which are known to show variations in their neonatal behavioral progress. Blood samples were assayed for thyroid hormones, known to be involved in heat production, and cortisol, which plays a role in tissue maturation before birth. In addition, colostrum samples were collected from the 56 ewes that gave birth to the lambs, and assayed for protein, fat, and vitamin contents. Heavy lambs (more than 1 SD above the breed mean), Blackface lambs, and singleton or twin lambs were quicker to stand and suck from their mothers than lightweight (more than 1 SD below the breed mean), Suffolk, or triplet lambs. Low birth weight lambs also had lower rectal temperatures than heavier lambs (P < 0.01), as did Suffolk compared with Blackface lambs (P < 0.001). Lambs that were slow to suck after birth had lower rectal temperatures than quick lambs, and this difference persisted for at least 3 d after birth. Within breed, heavy lambs had greater plasma triiodothyronine and thyroxine immediately after birth than light lambs. Blackface lambs had greater plasma triiodothyronine and thyroxine than Suffolk lambs but tended to have less cortisol. Colostrum produced by Blackface ewes had a greater fat content than that of Suffolk ewes (P < 0.001). Thus, lambs that are behaviorally slow at birth are also less able to maintain their body temperature after birth. Although part of their lower body temperature might be attributable to behavioral influences on thermoregulation, the data also suggest that physiological differences exist between these animals. These differences may be related to different degrees of maturity at birth.

Animals↗
PubMed2005

Frequency and cost of human intervention at lambing: an interbreed comparison.

The frequency of human intervention during lambing was assessed for 708 lambs and 162 ewes in up to four deliveries. In total, 21.8 per cent of the lambs born alive required some assistance at birth and 9.4 per cent were delivered manually. Assistance was required less frequently by twin lambs and ewe lambs, and Scottish blackface lambs required assistance less frequently than Suffolk lambs. Approximately one-third of the ewes were assisted in at least one delivery and 10 per cent were assisted in all their deliveries; however, less than 20 per cent of ewes were assisted more than once. A quarter of the lambs needed some human intervention to suck successfully, and Suffolk lambs needed help more frequently. The lambs born to almost half the first-parity ewes needed help to suck, but at later deliveries the lambs born to less than a third of the ewes needed assistance. In blackface flocks the survival of 100 lambs required 4.6 hours of human intervention whereas in Suffolk flocks 28 hours were required.

Animal Husbandry↗
PubMed2005

Breed, litter and parity effects on placental weight and placentome number, and consequences for the neonatal behaviour of the lamb.

Lamb survival is impaired in low birth weight lambs, and those that are slow to stand and suck. Many of the factors that influence lamb vigour, such as parity, litter size, and breed, may exert their effects, at least partially, before birth by influencing placenta development. Our hypothesis was that retarded lamb behavioural development was due to differences in placentation in these animals. Data were collected from Blackface and Suffolk lambs in the first 2 h after birth and placentas were collected when delivered. Suffolk lambs, which were behaviourally slower and had lower rectal temperatures than Blackface lambs, were associated with larger but less efficient placentas (placental efficiency defined as foetal weight supported per g placenta) with fewer foetal cotyledons than Blackface placentas. Triplet lambs were significantly slower than twin or single lambs to suck and had lower rectal temperatures. Although placenta efficiency increased with litter size, placenta and cotyledon weight, and cotyledon number increased with twinning but not thereafter. It seemed likely that triplet lambs suffered some placental insufficiency in comparison to other litter sizes. Lambs born to first parity mothers were slower to stand and reach the udder than lambs of more experienced ewes, and first parity ewes also had smaller and less efficient placentas although cotyledon number was not affected. Male lambs tended to be slower than female lambs for most behaviours, although rectal temperatures were not affected. The sire of the lamb also influenced lamb behaviour and rectal temperature. Both lamb sex and lamb sire influenced the average weight of placental cotyledons, thus some of the sire effect on the behaviour and birth weight of his progeny might be mediated through placental development. Lamb neonatal vigour was correlated with placental efficiency suggesting that lamb behaviour immediately after birth is related to placental development and function.

Animals↗
PubMed2003

Behavioural development in the neonatal lamb: effect of maternal and birth-related factors.

The survival of the neonate relies on the integrated expression of appropriate behaviours from both the mother and young. In precocious species, like the sheep, the speed with which the lamb stands and seeks the udder is related to lamb survival. In this study the effects of birth difficulty, lamb birth weight, ewe loss or gain in backfat from conception to delivery, ewe parity, litter size, and lamb sex on neonatal lamb behavioural development were investigated in over 500 lambs of two breeds (Scottish Blackface and Suffolk). Lambs that required assistance to be delivered were significantly slower to perform all neonatal behaviours than unassisted lambs (P<0.001), and were less active over the first 3 days after delivery (P<0.05). There were no effects of lamb birthweight that were not accounted for by the increased likelihood of requiring assistance in heavier birth weight lambs. Ewes that mobilised less body fat during their pregnancy produced lambs that stood and sucked quickly (P<0.001), and were more active over the first 3 days of life. Lambs born to first parity ewes were slower to stand and suck than lambs born to experienced ewes (P<0.001). There was an improvement in time taken by lambs to stand, seek the udder and to suck with each increase in ewe parity. Litter size had an additional retarding influence on the behaviour of multiple-born lambs that could not be accounted for by birthweight. In the Suffolk breed male lambs were slower to stand and suck than female lambs, this effect was not seen in Blackface lambs. These data demonstrate that lambs that require assistance at birth, even if they survive the birth process, lambs born to ewes that lose a lot of condition over pregnancy or first parity ewes, triplet lambs and, at least in some breeds, male lambs are slower to progress through the sequence of neonatal behaviours. These lambs are, therefore, at greater risk of not surviving to weaning.

Animals↗
PubMed1999

Physiological correlates of maternal-offspring behaviour in sheep: a factor analysis.

The onset of maternal behaviour in sheep is controlled by levels of oestrogen and progesterone in gestation and the release of oxytocin during delivery. Factor analysis was used to investigate the relationships between maternal behaviour, offspring behaviour, and maternal ovarian hormone levels during gestation in sheep. Ewes gave birth to lambs following embryo transfer between two breeds (Suffolk and Scottish Blackface), which differ in their expression of maternal behaviour. Plasma oestradiol-17beta concentration was significantly higher in Blackface ewes in the last 6 weeks of pregnancy, whereas plasma progesterone was higher in Suffolk ewes in early and mid gestation. Factor analysis revealed three factors that accounted for 50% of the total variation between variables. Factor 1 described lamb activity and had positive loadings for lamb behavioural latencies immediately postpartum, and negative loadings for sucking frequency. Factor 2 described some aspects of ewe maternal behaviour, and had positive loadings for ewe-lamb separation and lamb vocalisation, and negative loadings for ewe grooming behaviour and plasma oestradiol concentration. Factor 3 described ewe and lamb-sucking interactions, and had positive loadings for ewe moving as the lamb made sucking attempts, and negative loadings for ewe and lamb vocalisation. Factor 1 scores were significantly affected by lamb breed: Suffolk lambs received positive scores, indicating a longer latency to right and stand, whereas Blackface lambs had negative scores. Maternal progesterone concentration was significantly correlated with Factor 1 scores. Factor 2 and 3 scores were significantly affected by ewe breed. This study has shown that there are two behavioural axes to maternal behaviour in sheep, and that maternal oestradiol concentration is related to affiliative behaviours (e.g., grooming) but only weakly to ewe responsiveness to lamb-sucking attempts.

Animals↗
PubMed1997

A comparison of subjective and objective measures of reduction of psoriasis with the use of ultrasound, reflectance colorimetry, computerized video image analysis, and nitric oxide production.

BACKGROUND: Studies of antipsoriatic therapy often rely on subjective scoring. Objective measures have been developed but have not previously been compared with subjective scoring. OBJECTIVE: Our purpose was to compare subjective and objective measures of reduction of psoriasis with topical therapy. METHODS: A 2-week, double-blind, left-to-right comparative trial of betamethasone valerate against white soft paraffin was performed in 12 patients. The subjective scores were erythema, elevation, scale, and a composite total. Objective measures were nitric oxide production measured by chemiluminescence; erythema reflectance; ultrasound scan for thickness, scale, and echo-poor zone; and computerized image analysis of video images. RESULTS: Subjective and objective measures had similar power to detect therapeutic effect. The subjective measures showed greater variation and relatively overestimated improvement. There was correlation between measures and estimates for area, redness, and thickness. Nitric oxide production was the most powerful objective measure. CONCLUSION: Thickness determined by ultrasound scan and nitric oxide production are useful measures of reduction of psoriasis, which lend themselves to more powerful statistical tests than subjective interval data.

Administration, Topical↗
PubMed1997

Inducible nitric oxide synthase demonstrated in allergic and irritant contact dermatitis.

Eight allergic patch test reactions, eight irritant skin reactions induced by 3% sodium lauryl sulphate and six normal controls were biopsied. Biopsies were immunohistochemically stained with a mouse monoclonal antibody to inducible nitric oxide synthase (iNOS), and staining was quantified by computerised image analysis. Human chondrocytes induced to express iNOS were used as a positive control. A significant increase in iNOS was found in both irritant and allergic contact dermatitis. There were no differences in the distribution of expression of iNOS. The antibody used was confirmed by Western blotting not to cross-react with the endothelial isoform of nitric oxide synthase (NOS) but did cross-react with a 150 kDa protein, which may be neuronal NOS or an isoform of neuronal NOS.

Adult↗
PubMed1996

Interleukin-12 antagonist activity of mouse interleukin-12 p40 homodimer in vitro and in vivo.

Mo(p40)2 is a potent IL-12 antagonist that interacts strongly with the beta 1 subunit of the IL-12R to block binding of moIL-12 to the high-affinity mouse IL-12R. Mo(p40)2, alone or in synergy with the 2B5 mAb specific for the moIL-12 heterodimer, blocked IL-12-induced responses in vitro, Mo(p40)2 was thus used alone or with 2B5 mAb to examine the role of IL-12 in vivo, Mo(p40)2 caused a dose-dependent inhibition of both the rise in serum IFN-gamma levels in mice injected with endotoxin and the Th1-like response to immunization with KLH. Treatment with mo(p40)2 plus 2B5 anti-moIL-12 mAb also suppressed DTH responses to methylated bovine serum albumin but not specific allogeneic CTL responses in vivo. In each of these models, responses seen in mice treated with mo(p40)2 +/- 2B5 anti-moIL-12 mAb were similar to those observed in IL-12 knockout mice. Thus, mo(p40)2 can act as a potent IL-12 antagonist in vivo, as well as in vitro, and is currently being used to investigate the role of IL-12 in the pathogenesis of some Th1-associated autoimmune disorders in mice.

Animals↗
PubMed1996

Effect of ewe and lamb genotype on gestation length, lambing ease and neonatal behaviour of lambs.

To distinguish between ewe and lamb breed effects on prenatal growth, ease of parturition and early lamb behaviour, an embryo-transfer study was carried out using a hill breed (Scottish Blackface; liveweight: 54.25 +/- 1.03 kg, mean +/- s.e.m.) and a lowland breed (Suffolk; 80.33 +/- 1.52 kg) to obtain the four possible combinations of ewe and lamb. Data were collected from 38 Blackface ewes (18 with Blackface lambs and 20 with Suffolk lambs) and 41 Suffolk ewes (20 with Blackface lambs and 21 with Suffolk lambs); all ewes were given single embryos. Suffolk lambs had a significantly longer gestation than Blackface lambs (1.5 days, P < 0.01), regardless of ewe breed. Suffolk lambs also had a longer labour (20 min, P < 0.05) and were significantly more likely to require birth assistance (17/21, 81% of all assisted deliveries; P < 0.001), as were male lambs (19/21, 90%; P < 0.01). These variables were independent of ewe breed. Blackface lambs were significantly more active than Suffolk lambs in the first 2 h after birth; ewe breed had little effect on lamb behaviour. Blackface lambs stood twice as quickly as Suffolk lambs after birth (13 min v. 24 min; P < 0.001), and were significantly more likely to suckle within the first 2 h after birth (92% v. 66%; P < 0.05). The behavioural retardation of Suffolk lambs may be a consequence of their birth difficulty which increases their likelihood of suffering birth trauma and hypoxia at parturition. Together, these factors may increase the probability of neonatal death in these lambs.

Animals↗
PubMed1995

Effect of maternal undernutrition in early gestation on the development of fetal myofibres in the guinea-pig.

A 40% restriction in maternal feed intake throughout gestation in the guinea-pig results in a 35% reduction in fetal body weight at term and a 20-25% reduction in muscle fibre number. To investigate the effect of maternal undernutrition in early gestation, four nutritional treatments were used: controls-pregnant females fed ad libitum throughout gestation; TR-fed 60% ad libitum intake throughout gestation; ER-fed 60% ad libitum for the first third of gestation (until Day 25), then ad libitum to term; LR-fed ad libitum for the first 25 days, then 60% of ad libitum to term. The LR group were complicated by a high degree of fetal resorption and early littering of viable litters. The biceps brachii and soleus muscles were removed from neonates and total muscle fibre numbers determined. In a second experiment a further 8 pregnant guinea-pigs were fed 60% ad libitum until Day 15 of gestation only, and then rehabilitated onto an ad libitum diet (VER). Of these, 5 guinea-pigs were killed at term and the remaining 3 at 45 days gestation. Fetuses and placentae were obtained from all VER animals and compared with TR and controls of a similar age. Body weights were reduced in all restricted groups at term when compared with controls (P < 0.05) by 12, 40 and 50% for VER = ER, TR and LR groups, respectively. Biceps fibre number was reduced (P < 0.05) in ER, TR and LR groups by 28, 20 and 25%, respectively, but was not affected in the VER group. Soleus fibre number was not significantly affected by any nutritional treatment. Restriction for 15 days in early gestation caused a significant 20% increase in fetal weight at 45 days' gestation compared with controls, but muscle and placental weights were not affected. Analysis of placental components at Days 45 and 65 suggested that underfeeding in early gestation and subsequent refeeding caused some placental adaptations to increase the exchange-surface area. A short period of maternal undernutrition in the first third of gestation alone (ER), therefore, resulted in a biceps brachii fibre number deficit similar to that caused by restriction throughout gestation only if the period of restriction extended as far as Day 25. Furthermore, fetal weight at term was impaired by short-term nutritional restriction in early gestation. Restriction in the last two-thirds of gestation, following an ad libitum diet in the first third, caused a reduction in biceps fibre number and had a severe effect on the maintenance of pregnancy. It is probable that undernutrition in early gestation had an indirect effect on muscle fibre number by affecting the development of the placenta. This could be avoided by nutritional rehabilitation before Day 25 of gestation, but appeared to be permanent thereafter. Undernutrition after Day 25 may have had a direct effect on the development of secondary fibres.

Animals↗
PubMed1995

Squamous carcinoma following lichen planus of the vulva.

A 58-year-old woman presented with typical cutaneous features of lichen planus (LP). She had suffered from vulval pruritus for 3 years, and examination showed lesions suggestive of LP on the vulva. Three months later a plaque developed on the clitoral hood, and biopsy showed an invasive squamous carcinoma. After vulvectomy, features of LP were found in the excised specimen. Vulval LP should be carefully monitored for possible malignant transformation.

Biopsy↗
PubMed1994

Supplementation of a restricted maternal diet with protein or carbohydrate alone prevents a reduction in fetal muscle fibre number in the guinea-pig.

A 60% reduction in maternal feed intake is known to cause a reduction of approximately 20% in biceps brachii fibre number in the guinea-pig fetus. This investigation was designed to isolate the dietary component responsible by reducing all dietary components to 60% of the ad lib. level and supplementing the protein, carbohydrate or fat component to the level of the ad lib. intake. Fetal muscles were examined at 50 d gestation to determine numbers of primary and secondary fibres, and at term to determine total fibre number. Fetal and neonatal weights were reduced in all restricted groups (P < 0.05) when compared with ad lib. controls. At term this reduction was significantly less (P < 0.05) in the protein-supplemented group (20%) than in the 60%-restricted and fat-supplemented groups (43%) and the carbohydrate-supplemented group (34%). Biceps brachii fibre numbers were reduced in the 60%-restricted fat-supplemented groups by 14-16%, but fibre numbers were similar in control, protein-supplemented and carbohydrate-supplemented groups. Any reduction in fibre number was in the secondary fibre component of total fibre number. Therefore, biceps brachii fibre numbers were reduced only when maternal diets were deficient in both protein and carbohydrate.

Animal Nutritional Physiological Phenomena↗