Biomedical subjects

L Heasman

Publications and source records attributed to L Heasman.

At least 19 recordsLinked to original sources

PubMed2006

Smoking cessation as a dental intervention--views of the profession.

OBJECTIVE: To undertake a questionnaire-based survey to determine the attitudes and activities of dental professionals in primary care in the Northern Deanery of the UK in relation to providing smoking cessation advice. METHODS: Questionnaires for dentists, hygienists and dental nurses were sent to hygienists to distribute to other members of the team. The information collected included: smoking status of the professionals and the practice; roles of the dental team in giving smoking cessation advice; levels of training received; and potential barriers to giving this brief intervention. RESULTS: Over 90% of practices were smoke-free environments and significantly more dental nurses (23%) were smokers compared to dentists (10%) and hygienists (7%) (p<0.01). The majority of dentists and hygienists enquired about smoking status of their patients and all three groups believed that hygienists and dentists should offer brief smoking cessation advice. Potential barriers to delivering smoking cessation advice were identified: lack of remuneration; lack of time; and lack of training. CONCLUSION: Dental teams in primary care are aware of the importance of offering smoking cessation advice and, with further training and appropriate remuneration, could guide many of their patients who smoke to successful quit attempts.

Analysis of Variance↗

PubMed2006

Smoking cessation advice for patients with chronic periodontitis.

BACKGROUND: There are limited data on the utility of dental professionals in providing smoking cessation counselling in the UK. OBJECTIVES: The purpose of this study was to determine quit rates for smokers with chronic periodontitis who were referred to a dental hospital for treatment. MATERIALS AND METHODS: Forty-nine subjects with chronic periodontitis who smoked cigarettes were recruited. All subjects received periodontal treatment and smoking cessation advice as part of an individual, patient-based programme provided by dental hygienists trained in smoking cessation counselling. Smoking cessation interventions included counselling (all patients), and some patients also received nicotine replacement therapy (NRT) and/or Zyban medication. Smoking cessation advice was given at each visit at which periodontal treatment was undertaken (typically four to six visits) over a period of 10-12 weeks. Smoking cessation advice was also given monthly during the programme of supportive periodontal care over the following nine months. Smoking status was recorded at three, six and 12 months and was confirmed with carbon monoxide (CO) monitors and salivary cotinine assays. RESULTS: Forty-one per cent, 33%, 29% and 25% of patients had stopped smoking at week four, months three, six and 12, respectively. Gender, age, the presence of another smoker in the household, and baseline smoking status (determined using subject-reported pack years of smoking) were not significant predictors of quit success (P < 0.05). Baseline CO levels were significantly associated with quit success, however, and were significantly higher in those subjects who continued to smoke compared to those subjects who were quitters at week four, month three and month six (P < 0.05). CONCLUSION: Success rates in quitting smoking following smoking cessation advice given as part of a periodontal treatment compared very favourably to national quit rates achieved in specialist smoking cessation clinics. The dental profession has a crucial role to play in smoking cessation counselling, particularly for patients with chronic periodontitis.

Adult↗

PubMed2006

The effect of smoking on periodontal treatment response: a review of clinical evidence.

BACKGROUND: Smoking has been identified as a significant risk factor for periodontal diseases and is regarded as being responsible for incomplete or delayed healing in patients following treatment. AIM AND METHOD: The aim of this conventional review was to review, collate and tabulate the relative effectiveness of treatments of chronic periodontitis in smokers, non-smokers and ex-smokers. OBSERVATIONS: The majority of clinical trials show significantly greater reductions in probing depths and bleeding on probing, and significantly greater gain of clinical attachment following non-surgical and surgical treatments in non-smokers compared with smokers. This benefit is also seen at class I and II furcation sites and in patients prescribed systemic or local antimicrobial treatments. CONCLUSIONS: Data from epidemiological, cross-sectional and case-control studies strongly suggest that quitting smoking is beneficial to patients following periodontal treatments. The periodontal status of ex-smokers following treatment suggests that quitting the habit is beneficial although there are only limited data from long-term longitudinal clinical trials to demonstrate unequivocally the periodontal benefit of quitting smoking.

Chronic Disease↗

PubMed2005

Scrapie infection alters the distribution of plasma metabolites in diseased Cheviot sheep indicating a change in energy metabolism.

Nuclear magnetic resonance (NMR) spectroscopy has been used to profile the metabolic status of plasma from; sheep showing clinical signs of scrapie, those known to be infected with scrapie but yet to show clinical signs, and control animals. The NMR measurements have shown that energy metabolism in scrapie infected animals is altered before the onset of clinical symptoms. These metabolic changes may provide the foundation for a pre-clinical diagnostic test for scrapie in sheep.

Animals↗

PubMed2005

Assessing adherence with toothbrushing instructions using a data logger toothbrush.

OBJECTIVES: To evaluate patient compliance with toothbrushing instructions using a data logger and a brushing diary. METHODS: Dental patients were provided with powered toothbrushes modified to carry electronic data loggers. Demonstration of the most effective way to use the toothbrush was provided with instructions to brush for 2 minutes morning and evening. Data logger brushes were supplied for two episodes of 8 weeks. Brushing time was also recorded in a diary during episode 1. RESULTS: Data from 14 brushes (2,287 recordings) were used to evaluate compliance in episode 1 Nine brushes (1,526 recordings) were used in episode 2 A total of 2,333 brushing events were reported manually in the diaries. Data logger records during episode 1 showed that only 34% of events were compliant with the instruction of a 2 minute brushing time, 20% were partially compliant (within +/-30s of 2 minutes), and 46% of events were non-compliant (>30s from 2 minutes). The respective proportions for episode 2 were 24%, 24% and 52%. Diary data reported 58% of events as compliant with 42% non-compliant. CONCLUSIONS: Manually completed brushing diaries do not provide an accurate reflection of subjects' compliance with toothbrushing instructions.

Data Collection↗

PubMed2005

The effect of quitting smoking on chronic periodontitis.

OBJECTIVES: To evaluate longitudinally the effect of smoking cessation on clinical and radiographic outcomes following non-surgical treatment in smokers with chronic periodontitis. MATERIAL AND METHODS: Forty-nine smokers with chronic periodontitis who wished to quit smoking were recruited. Full-mouth probing depths, bleeding and plaque data were recorded at baseline, 3, 6 and 12 months. Clinical attachment levels were recorded at target sites and subtraction radiography was used to assess bone density changes. Patients received non-surgical periodontal therapy during the first 3 months and supportive periodontal care over the remainder of the study. Smoking cessation counselling was provided according to individual need. RESULTS: After 12 months, of patients with complete data, 10 had continuously quit smoking (20% of the original population), 10 continued smoking and six were oscillators (those patients who quit and then relapsed). There were no differences between the groups following treatment with respect to mean clinical or radiographic parameters. Analysis of probing depth reductions between baseline and month 12, however, and comparing quitters with the other two groups combined, demonstrated a significant difference in favour of quitters (p<0.05). Furthermore, quitters were significantly more likely to demonstrate probing depth reductions > or =2 and > or =3 mm than non-quitters and oscillators (p<0.05). CONCLUSION: Quitting smoking has an additional beneficial effect in reducing probing depths following non-surgical treatment over a 12-month period.

Adult↗

PubMed2005

The crossover design to evaluate the efficacy of plaque removal in tooth-brushing studies.

OBJECTIVES: To evaluate the crossover clinical trial design to assess plaque removal efficacy of the Sonicare Elite. MATERIAL AND METHODS: A single-cohort, 12-week, two-treatment, single-blind, crossover clinical trial recruited 45 subjects. Plaque was recorded using the modified Quigley and Hein index plaque index (PI). After screening, subjects used the toothbrush for 2 weeks and were reminded to abstain from tooth cleaning 12-18 h prior to appointments. At visit two, subjects were randomized to 2 or 2(1/2) min. brushing time. PIs was recorded pre- and post-brushing. Subjects brushed for the allocated time for a further 2 weeks. At visit 3, PIs were recorded pre- and post-brushing. Two weeks later, at visit 4, the subjects crossed over and the protocol was repeated. RESULTS: There was no evidence of a learning effect within each arm of the crossover. A significant period effect was detected; however, no significant treatment by period effect was found. 2(1/2) min. brushing removed more plaque at full mouth (p=0.037), smooth (p=0.012) and lingual (p=0.002) sites compared with 2 min. CONCLUSION: The crossover design is a valid model for assessing plaque removal efficacy in tooth-brushing studies where no carry-over effect is clinically plausible.

Adolescent↗

PubMed2004

A clinical comparison of an oscillating/rotating powered toothbrush and a manual toothbrush in patients with chronic periodontitis.

OBJECTIVES PRIMARY OBJECTIVE: To compare the relative efficacy of an oscillating/rotating powered toothbrush to that of a conventional manual toothbrush in a group of periodontal patients over a 16-month period with respect to plaque control. SECONDARY OBJECTIVE: To compare differences in pocket depth (PD) and bleeding index (BI) between the two groups over a 16-month period. MATERIAL AND METHODS: Forty patients were recruited to a 16-month, single-blind, two-group, randomised, parallel group clinical trial to compare the effects of manual and oscillating/rotating powered toothbrushes in a cohort of patients with chronic periodontitis. None of the patients had previous experience of using an oscillating/rotating brush and had a mean plaque index (PI) of > 2.0 (modified Quigley and Hein index) at baseline. Patients were stratified by gender, age and smoking status then randomised to using a manual or an oscillating/rotating brush for the duration of the study. Conventional non-surgical periodontal therapy was undertaken within the first month after baseline. PI was the primary outcome measure with PDs and BI also recorded at baseline and months 3, 6, 10 and 16. RESULTS: Mean full-mouth (FM) scores at baseline for oscillating/rotating brushing and manual brushing groups were as follows: PI, 3.4 and 3.5; BI, 1.7 and 1.5; and PD, 3.4 and 3.3. The mean reduction in FM scores from baseline to 16 months were: PI, 0.72 and 0.75; PD, 0.43 and 0.57; and BI, 0.74 and 0.83, respectively. Repeated measures ANOVA were used to compare differences between groups (adjusted for baseline levels) at months 3, 6, 10 and 16 and showed no statistically significant difference between groups for PI and PD (p > 0.05). A difference of 0.2 BI units was detected in favour of the manual brushing group (p = 0.04). CONCLUSION: Over a 16-month period, there were no differences in PI reduction or PD reduction between patients who underwent non-surgical management of chronic periodontal disease and used either an oscillating/rotating powered toothbrush or a conventional manual toothbrush. A difference in gingival bleeding reduction was detected in favour of the patients allocated the manual brush.

Adult↗

PubMed2004

Efficacy of plaque removal of the Sonicare Elite versus the Sonicare Advance from hard-to-reach sites.

OBJECTIVE: To compare the Sonicare Elite with the Sonicare Advance in terms of the reduction in supragingival plaque in the posterior, hard-to-reach areas of the mouth. METHOD: This was a single-cohort, 6-week, two-treatment, single-blind, cross-over clinical trial that recruited 45 subjects. Plaque scores were recorded throughout the study using a modification of the Quigley and Hein plaque index (PI). All subjects had a minimum pre-brushing PI of 1.8 at screening following 24 h abstention from tooth cleaning. Subjects then used a Sonicare Advance powered toothbrush at home for 4 weeks for familiarisation purposes. At the next visit (2), subjects were given either the Sonicare Elite or the Sonicare Advance powered toothbrush for a further 2 weeks of home use. Twenty-four hours prior to visit 3, subjects abstained again from tooth cleaning. At visit 3, the PI was recorded pre- and post-tooth brushing and then all remaining "mature" plaque was removed professionally with a dental prophylaxis. After a further period of 24 h (to accumulate new plaque) without tooth brushing the subjects returned for visit 4 at which PIs were again recorded pre- and post-tooth brushing. The subjects were then given the second toothbrush in the cross-over sequence and attended for visits 5 and 6 at which the protocol for visits 3 and 4 was repeated. RESULTS: The Sonicare Elite powered toothbrush was more effective than the Sonicare Advance model in removing both mature and newly formed plaque. The magnitude of the differences between the toothbrushes for all posterior sites, interproximal and smooth surfaces, respectively, was 0.35 U (p<0.001), 0.39 U (p<0.001) and 0.32 U (p<0.001) of the modified Quigley and Hein PI. There was no evidence of a significant period effect comparing data from visits 5 and 6 against those from visits 3 and 4. There was, however, a significant visit effect with full-mouth (p<0.01), interproximal (p<0.001) and smooth surface (p<0.01) post-brushing plaque scores being significantly lower at visits 4 and 6 than at visits 3 and 5. CONCLUSION: The data support the observation that the Sonicare Elite toothbrush is more effective than the Sonicare Advance model in removing both newly formed and mature plaque from all posterior, interproximal and smooth tooth surfaces.

Adolescent↗

PubMed2002

Studies of embryo transfer from cattle clinically affected by bovine spongiform encephalopathy (BSE).

Semen from 13 bulls, eight with clinical bovine spongiform encephalopathy (BSE), was used to artificially inseminate (AI) 167 cows with clinical BSE, and their resultant embryos were collected non-surgically seven days after AI. The viable and non-viable embryos with intact zonae pellucidae were washed 10 times (as recommended by the International Embryo Transfer Society) then frozen. Later, 587 of the viable embryos were transferred singly into 347 recipient heifers imported from New Zealand, and 266 live offspring were born of which 54.1 per cent had a BSE-positive sire and a BSE-positive dam. The recipients were monitored for clinical signs of BSE for seven years after the transfer, and the offspring were monitored for seven years after birth. Twenty-seven of the recipients and 20 offspring died while being monitored but none showed signs of BSE. Their brains, and the brains of the recipients and offspring killed after seven years, were examined for BSE by histopathology, PrP immunohistochemistry, and by electron microscopy for scrapie-associated fibrils. They were all negative. In addition, 1020 non-viable embryos were sonicated and injected intracerebrally into susceptible mice (20 embryos per mouse) which were monitored for up to 700 days, after which their brains were examined for spongiform lesions. They were all negative. It is concluded that embryos are unlikely to carry BSE infectivity even if they have been collected at the end-stage of the disease, when the risk of maternal transmission is believed to be highest.

Animals↗

PubMed2002

Testing the efficacy of 2 prototype brush heads for a powered toothbrush: refining the model.

OBJECTIVES: To compare 2 prototype powered toothbrush (PTB) heads (A, B) to a marketed head (Sensiflex 2000) for plaque removing efficacy on the Philips/Jordan HX2550 PTB. MATERIALS AND METHODS: A 2-week, 3-group, single-blind trial recruited 78 volunteers (18-25). Plaque indices (PIs) were recorded at screening and 14 days later at baseline. Subjects were stratified (gender and PI) and then asked to abstain from oral hygiene measures for 48 h. A supervised episode of brushing with the allocated PTB head followed. Subjects then used the PTBs at home for the next 12 days before being asked to abstain from all oral hygiene measures for another 48 h prior to a second supervised brushing episode. Plaque was scored using a new modification of the Quigley & Hein Index (PI) at full mouth (FM), interproximal (IP) and smooth surfaces (SS). PIs were recorded before and after the supervised brushing episodes to enable the means of the within subject differences (pre- to post-brushing) to be compared between groups (ANOVA/t-tests). RESULTS: There were no significant differences in PI between groups at baseline or prior to the supervised brushings (p>0.05). Highly significant, mean reductions in PIs (approximately 1/2 of one PI unit) were observed for design B compared with the Sensiflex 2000 at FM and IP sites (p<0.0001) for both supervised brushing episodes. A significant reduction in PI at SS was seen only after the first brushing episode (p=0.0004). For design A, PI reductions were consistently greater than those for the Sensiflex 2000 but differences were only significant at the p<0.05 level. CONCLUSION: It is concluded that this model of clinical trial has sufficient power to demonstrate clinical superiority with respect to plaque removal for PTBs and can be used for testing one or more prototype designs of brush heads.

Adolescent↗

PubMed2001

Local delivery of chlorhexidine gluconate (PerioChip) in periodontal maintenance patients.

AIM: The aim of this randomised, split-mouth, single-blind study was to determine the efficacy of controlled-release delivery of chlorhexidine gluconate 2.5 mg (PerioChip) in patients with residual bleeding pockets (>5 mm) at least 3 months following oral hygiene and root debridement phase therapy. MATERIAL AND METHODS: 26 patients (non-smokers) were screened and potential study sites identified. Clinical parameters recorded at baseline and all subsequent visits were plaque index (PI), pocket probing depth (PPD), bleeding index (BI) and clinical attachment level (CAL). All study sites were debrided using ultrasonic instrumentation. PerioChips (PC) were placed in the selected sites of two quadrants (left or right) whilst identified sites in the remaining quadrants were left without adjunctive antimicrobial treatment. Clinical measurements were made at follow-up visits after 1, 3 and 6 months. Mean changes from baseline in PPD, BI and CAL were calculated with the patient as the experimental unit and comparability between the treatments was determined using t-tests. RESULTS: At baseline there were no significant differences between PC and control sites for mean PI, PD, BI or CAL. The mean (SE) reductions in PPD for PC and control treatments were: 0.47 (0.1), 0.46 (0.1); 0.76 (0.1), 0.55 (0.1); 0.78 (0.1), 0.45 (0.1) for months 1, 3 and 6 respectively. Only at month 6 did the difference between treatments approach statistical significance (p=0.06). Mean (SE) reductions in CAL over the same periods were: 0.17 (0.1), 0.04 (0.08); 0.38 (0.1), 0.21 (0.1); 0.43 (0.1), 0.15 (0.09) p=0.048. Mean (SE) reduction in BI between PC and control treatments only reached statistical significance at 6 months: 1.08 (0.1), 0.59 (0.1) p=0.05. CONCLUSION: These data suggest that PerioChip is beneficial for patients on maintenance therapy although the benefit is not apparent until 6 months after placement.

Adult↗

PubMed2001

A comparative study of two powered toothbrushes and one manual toothbrush in young adults.

The aim of this 3-group, 3-treatment, single-blind, parallel group study was to evaluate and compare the efficacies of the Philips/Jordan HP735 powered toothbrush, the Braun/Oral-B D7 powered toothbrush, and the Oral-B Advantage B35 manual toothbrush in young adults (18-25 years). Full mouth mean (SD) modified Turesky Plaque Index (PI) and the Löe & Silness Gingival Index (GI) were recorded at baseline. After 24 hours abstinence from oral hygiene, the PI was recorded and each subject was given one of the test brushes with detailed instructions for use. Each subject then brushed under supervision for 90 seconds, during which time mean (SD) toothbrushing forces (TBF) were recorded. PIs were recorded immediately after brushing, and the subjects were then discharged for 6 weeks to use the allocated toothbrush at home. After 6 weeks, PI, GI and TBF were again recorded. There were no significant differences (ANOVA) for PI and GI between groups at baseline, or for PI following brushing at 24 hours. After 6 weeks, the powered brushes produced lower mean PI (SD) scores than the manual brushes, but the differences were significant only at interproximal sites. Mean GI scores for the HP735 group were similar at baseline and at 6 weeks, although for the other brushes the GI scores actually increased over this period. Mean (SD) TBF (grams/force) at baseline and 6 weeks, respectively, for the brushes were; HP735 233 (205), D7 159 (58), B35 279 (122) (p = 0.026): HP735 194 (86), D7 141 (57), B35 297 (113) (p = 0.0001). The within-group variability for the HP735 TBF reduced considerably over 6 weeks, which is possibly because of the click-force threshold feature of this brush.

Adolescent↗

PubMed2001

Maternal nutritional manipulation of placental growth and glucose transporter 1 (GLUT-1) abundance in sheep.

Glucose transporter 1 (GLUT-1) is the predominant glucose transporter in the placenta but the extent to which its abundance is nutritionally regulated is unknown. This study investigated the effects of restricted maternal nutrition between day 28 and day 80 of gestation followed by re-feeding to either meet or to exceed the total energy requirements on placental size and GLUT-1 abundance at mid-gestation (that is, day 80) and near to term (that is, days 140-145 of gestation; term = 147 days). Singleton bearing ewes either consumed 8.7-9.9 MJ day(-1) of metabolizable energy (that is, well fed) or 3.2-3.8 MJ day(-1) of metabolizable energy (that is, nutrient restricted) from day 28 to day 80 of gestation, after which stage they consumed either 6.5-7.5 MJ day(-1) (that is, adequately fed) or 8.0-10.9 MJ day(-1) (that is, well fed) of metabolizable energy until near to term. In all ewes, at both sampling dates, the abundance of GLUT-1 was higher in the maternal component than in the fetal component of the placenta. Immunohistochemistry confirmed that GLUT-1 was located in the maternal uterine syncytium. At day 80 of gestation, placental mass was lower (P < 0.05) in the nutrient restricted group, but there was no difference in the abundance of GLUT-1 between the nutrient restricted group and the well fed group. At near term, placental mass was greater (P < 0.05) in ewes that were nutrient restricted during early to mid-gestation and then adequately fed up to term compared with ewes that were well fed during early to mid-gestation. This increase was associated with a higher (P < 0.05) abundance of total placental GLUT-1 and a larger fetus. There was no effect of previous nutrient restriction on placental mass, fetal weight or GLUT-1 abundance at term, when ewes were well fed in the second half of gestation. In conclusion, maternal nutrient restriction between early to mid-gestation alters placental growth but has no effect on placental GLUT-1 abundance. Increasing maternal feed intake to meet calculated energy requirements in previously nutrient restricted ewes during the second half of gestation, increases placental mass and fetal weight, and the abundance of GLUT-1, an adaptation not observed if maternal food intake is increased above requirements.

Analysis of Variance↗

PubMed2000

Testing the efficacy of plaque removal of a prototype brush head for a powered toothbrush.

BACKGROUND/AIMS: The principal aim of the study was to compare the efficacy of a powered toothbrush (PTB) prototype (B) brush head in removing dental plaque to the relative efficacy of a marketed model (A). METHOD: A 12-week, 2-group, 2-treatment, double-blind trial of 2, two-brush heads (with the same power unit) recruited 62 volunteers (18-25 years) who were non-clinical university students. After a screening visit, 31 subjects were allocated to each of groups A and B at baseline with stratification according to gender and plaque index. After 48 h of plaque growth, subjects underwent a timed and supervised brushing episode with the allocated PTB (visit 1). Subjects then used the PTBs at home for 12 days before being recalled (visit 2) and asked again to abstain from all oral hygiene measures for 48 h. Supervised brushing was repeated (visit 3) before the subjects were dismissed for a further 10-week, unsupervised period of home use of the PTBs. The sequence of visits (2 and 3) was then repeated at visits 4 and 5. RESULTS: The sole outcome variable was plaque which was scored at all visits using the modified Quigley & Hein Index (PI) at full mouth (FM), interproximal (IP) and smooth surfaces (S). At visits 1, 3 and 5, the PI was recorded both before and after supervised brushing. There were no significant differences in PI between the brushing groups at baseline, visit 1, visit 2 or visit 5 (2 sided t-test). At visit 3, the prototype achieved significantly lower PIs than the marketed PTB brush head for IP (and FM) surfaces, this difference was most apparent on posterior tooth surfaces. For within-group changes, PIs at visit 2 were significantly lower than those at baseline (paired t-test), an observation which may be attributable to the improved cleaning and 'novelty effect' of a PTB. The PIs at visit 5 were significantly higher than the baseline values (paired t test) and this may be accountable to an element of Hawthorne effect and/or, a fall off in compliance over the entire 12 weeks. CONCLUSION: We conclude that this in vivo model is appropriate for testing the efficacy of PTB prototypes but only over a 2-week period, as the inter-group differences were not maintained over the full 12 weeks of the trial.

Adolescent↗

PubMed2000

Influence of thyrotropin-releasing hormone administration at birth on thermoregulation in lambs delivered by cesarean.

OBJECTIVE: We examined the hypothesis that exogenous stimulation with thyrotropin-releasing hormone immediately before umbilical cord clamping can improve thermoregulation in near-term lambs delivered by cesarean. STUDY DESIGN: Twin lambs were injected with either saline solution alone (control, n = 12) or thyrotropin-releasing hormone in saline solution (n = 16) and were immediately placed in a warm (30 degrees C; n = 14) or cool (15 degrees C; n = 14) ambient temperature. In vivo measurements of temperature control (colonic temperature, oxygen consumption, and incidence of shivering) were then performed during the first 6 hours after birth, in conjunction with plasma thyroid hormone measurements. Brown adipose tissue was then sampled for measurement of uncoupling protein 1 abundance. RESULTS: Plasma triiodothyronine concentrations were significantly higher in lambs treated with thyrotropin-releasing hormone than in control lambs between 3 and 6 hours after birth, as were plasma thyroxine concentrations 1 and 5 hours after birth. Delivery temperature had no effect on plasma thyroid hormone concentrations. At 6 hours after birth the abundance of uncoupling protein 1 was higher in lambs treated with thyrotropin-releasing hormone than in control lambs. Lambs treated with thyrotropin-releasing hormone exhibited a lower incidence of shivering than did control lambs between 5 and 6 hours after birth, and an effect of ambient temperature on the incidence of shivering was observed only in the control group. From 3 to 6 hours after birth colonic temperature was significantly higher in cool-delivered lambs treated with thyrotropin-releasing hormone than in the control group. Oxygen consumption was higher in cool-delivered lambs than warm-delivered lambs, but this was not influenced by thyrotropin-releasing hormone. Irrespective of delivery temperature, lambs treated with thyrotropin-releasing hormone possessed more pericardial adipose tissue and hepatic glycogen than did control lambs. CONCLUSION: Thyrotropin-releasing hormone treatment stimulated thyroid hormone secretion in the neonatal lamb and improved thermoregulation during the first 6 hours after birth in near-term lambs delivered by cesarean under cool conditions.

Adipose Tissue, Brown↗

PubMed2000

Maternal nutrient restriction during early to mid gestation alters the relationship between insulin-like growth factor I and bodyweight at term in fetal sheep.

The present study was designed to determine whether altered placental size, as a consequence of maternal nutrient restriction in sheep between 28 and 77 days gestation, is associated with a modified relationship between fetal weight or dimensions and plasma insulin-like growth factor (IGF) I concentration or abundance of hepatic IGF-I and IGF-II mRNA close to term. Singleton-bearing ewes consumed either 1.2x (controls, n = 19) or 0.5x (nutrient restricted, n = 28) their metabolizable energy (ME) requirements from 28 to 77 days gestation, after which all ewes were fed in order to fully meet their ME requirements for maintenance and pregnancy. Close to term (145 +/- 1 days) plasma IGF-I concentration in cord blood was similar between groups, but only significantly correlated with fetal bodyweight, thoracic circumference, crown-rump length and lean body mass in lambs born to control (r2 0.38, 0.76, 0.33, 0.42; P<0.001), and not to nutrient-restricted (r2 = 0.01, 0.11, 0.01, 0.02) ewes. There were no differences in fetal hepatic expression of IGF-I and IGF-II mRNA between groups close to term. In conclusion, maternal nutrient restriction in early to mid gestation followed by feeding to requirements up to term alters the relationship between fetal IGF-I, bodyweight and length. Increasing maternal nutrition in later gestation after a prolonged period of nutrient restriction may stimulate fetal nutrient supply such that fetal growth is enhanced without an increase in plasma IGF-I. As a result, there is a loss of the relationship between fetal weight and plasma IGF-I concentration observed in fetuses whose mothers are fed adequately throughout gestation.

Animals↗

PubMed2000

Influence of relative size at birth on growth and glucose homeostasis in twin lambs during juvenile life.

The effect of differences in size at birth on growth and glucose homeostasis between female twin lambs during juvenile life was examined. Twenty-six sets of twins were entered into the study, of which ten were used for organ sampling at birth and 16 were studied over the first year of life. Eleven sets were defined as being mismatched for birthweight as the weight difference between twins was >25%, with light lambs weighing 4.1 +/- 0.3 kg and heavy lambs weighing 5.1 +/- 0.1 kg. All remaining twins were matched in bodyweight, weighing 4.6 +/- 0.5 kg. During the rapid period of juvenile growth (i.e. one, three and six months of age) and following stabilization of bodyweight (i.e. 12 months of age) glucose tolerance tests were performed by intravenously injecting 0.8 mg kg(-1) bodyweight glucose. This was followed the next day with an insulin tolerance test, performed by intravenously injecting 0.08 units kg(-1) bodyweight insulin. At birth there were no differences in organ weight as a fraction of total bodyweight between matched and mismatched twins, but the ratio of liver to brain weight was lower in light compared with heavy twins. Light lambs remained lighter than their twins up to six months of age, and crown-rump length was also shorter. At one and three months of age there were no differences in basal plasma glucose concentrations between the groups, but glucose tolerance was greater in light compared with heavy lambs at one and six months of age. Insulin tolerance was greater in light compared with matched lambs at one and six months of age. In conclusion, it has been shown that size at birth of one twin in relation to its co-twin is one factor determining glucose regulation during postnatal life. This not only affects glucose and insulin tolerance but also growth over the first six months of age.

Abdomen↗