Insulin secretion and sensitivity in hyperthyroidism

To examine the effect of hyperthyroidism on carbohydrate metabolism, we studied glucose-stimulated insulin secretion and glucose utilization in 8 subjects with Graves' disease before and after treatment for hyperthyroidism and 8 age-, sex- and weight-matched normal subjects. Subjects with Graves' disease had significant elevated serum levels of thyroxine (24.81 +/- 2.44 micrograms/dl, mean +/- SEM) and triiodothyronine (459 +/- 5.5 ng/dl, mean +/- SEM). Simultaneous measurement of plasma glucose, serum insulin and C-peptide levels during fasting and every 30 minutes up to 180 minutes after 75 g oral glucose loading was determined. In addition, plasma glucose, serum insulin and serum C-peptide were measured during euglycemic glucose clamp with insulin infusion of 40 mU/m2 min-1. Mean fasting plasma glucose (P less than 0.05, serum insulin (P less than 0.005) and serum C-peptide (P less than 0.005) levels were significantly higher in the hyperthyroid patients. After glucose loading, the plasma glucose (P less than 0.05), serum insulin (P less than 0.05) and C-peptide (P less than 0.05) responses were significantly higher in hyperthyroid patients at all times up to 180 minutes. During euglycemic clamp studies, the steady-state serum insulin levels were identical in the two groups. The glucose disposal rate was lower in hyperthyroid patients before treatment (P less than 0.01) than in normal subjects. After thyroid function had been normalized for 2 to 4 weeks, the glucose disposal rate increased significantly (P less than 0.05), but was still significantly lower than those of normal subjects (P less than 0.05). Our data show that patients with Graves' hyperthyroidism manifest glucose intolerance, hyperinsulinemia and insulin resistance.     

Epidural analgesia improves postoperative nitrogen balance.

Postoperative nitrogen balance was monitored in twelve patients undergoing hysterectomy under either epidural analgesia or general anaesthesia. The mean cumulative five-day nitrogen losses were significantly lower after epidural analgesia than after general anaesthesia. Nitrogen sparing presumably results from inhibiting the stress-induced release of catabolic hormones, since epidural analgesia abolished postoperative hyperglycaemia and increase in plasma cortisol concentrations. No adverse effects of inhibiting the stress response were observed. Neurogenic stimuli thus play a crucial part in the catabolic response to surgery. Inhibiting the endocrine metabolic response to trauma by neurogenic blockade may reduce the morbidity precipitated in high-risk patients by the catabolic response to surgery.     

Plasma concentrations of thyroid hormones in dogs: influence of sampling hour, breed and age

Thyroxine (T4) and triiodothyronine (T3) plasma concentrations have been determined during 24-hr sampling periods in six mongrels (age 12-36 months), six beagles (age 35-37 months), three labradors (age 3.5 months) and three beagles (age 5 months). The mean T4 levels of the labradors were significantly lower than the values found for mongrels or older beagles (P less than 0.05), whereas T3 was higher in the 5 month old beagles compared to the mongrels (P less than 0.001), young beagles (P less than 0.05) or labradors (P less than 0.01). Circadian and ultradian rhythmicities have been evaluated by cosinor and Fourier analysis. Mongrels and older beagles did have a 12-hr rhythmicity in plasma T4 (P less than 0.05), whereas 5 month old beagles had a circadian one (P less than 0.01). A 12-hr rhythmicity was also found for T3 in the older Beagles (P less than 0.05). However, Fourier analysis indicated that the daily variation in T4 and T3 plasma levels was inadequately mathematically described by single sinusoidal rhythm and that more harmonic components are to be taken into account. The obtained data during a 24-hr period indicate that T4 and T3 concentrations in plasma may vary according to breed, age and sampling hour.     

Changes in plasma IL-1beta, TNF-alpha and IL-6 after total hip replacement surgery in general or regional anaesthesia

Different anaesthetic methods influence the neuro-immuno-endocrine biologic responses to surgery and may thus possibly interfere with the postoperative course and development of complications. The neuroendocrine system is closely related to the cytokine network. In this study, the effects of general anaesthesia (n=6) and regional spinal/epidural anaesthesia (n=6) on the cytokine response (IL-1beta, TNFalpha, IL-6) to uncemented total hip replacement surgery were evaluated. The postoperative clinical course was uneventful in every case. In both groups, only very low values of plasma IL-beta were measured perioperatively, whereas plasma IL-6 increased postoperatively with peak values 4 h after surgery. The changes in plasma TNF-alpha were not significant. No significant differences in plasma TNF-alpha or IL-6 were found between patients operated in general or in regional anaesthesia. This suggests minor influence of plasma cytokines on the possible beneficial effects of regional anaesthesia on the clinical course after surgery in low risk patients. There were slightly higher TNF-alpha and IL-6 levels after the operation and significantly lower cortisol levels during the operation in the regional anaesthesia group compared to the general anaesthesia group, giving rise to a significant inverse correlation between peak values of IL-6 and peak values of cortisol. This supports the theory that after surgery the inhibitory effect of cortisol on monocyte cytokine production overrides adrenergic stimulation.     

Echocardiographic evaluation of space shuttle crewmembers

Echocardiographic measurements were obtained before and after space flight from 17 members of four shuttle crews. Measurements obtained 1 h after landing (L+0) compared with preflight values (n = 7) demonstrated an increase in heart rate (HR) (16 beats/min, 30.5%, P less than 0.05), mean arterial pressure (12%, P less than 0.05), and systemic vascular resistance (34%, P less than 0.05). End-diastolic volume index (EDVI) fell 17 ml/m2 (-23%, P less than 0.005) and stroke volume index (SVI) fell 15 ml/m2 (-28%, P less than 0.05). Repeat measurements taken 1-2 wk later (n = 17) demonstrated that HR had returned to normal (4 beats/min, P less than 0.05); however, EDVI remained significantly below preflight levels (-11%, P less than 0.005). End-systolic volume index (ESVI) was also still significantly lower (-23%, P less than 0.01). This delayed recovery occurred despite ability of the subjects to fully ambulate and exercise during the postflight period. These results indicate that spaceflight induces significant changes in heart volume affecting left ventricular function. The exact reasons for these specific changes remain unknown and will require additional measurements before, during, and after flight. The prolonged recovery period for the present subject group probably relates to their high level of aerobic conditioning.     

不同麻醉方法对胃肠道肿瘤手术病人细胞免疫功能的影响

目的:探讨不同麻醉方法对胃肠道肿瘤患者围术期外周血T细胞亚群以及白细胞介素-2(IL-2)的影响.方法:选择胃肠道肿瘤手术患者40例,随机分为两组.采用单纯全麻者为对照组,采用全麻复合硬膜外麻醉者为治疗组.分别于麻醉前、麻醉后不同时间点抽取静脉血,流式细胞术测定CD4+T及CD8+T细胞亚群数量,ELISA法测定血清IL-2的浓度.结果:麻醉后两组患者的CD4+T细胞、CD4+/CD8+比值和血清IL-2浓度均有所下降,与麻醉前比较差异有统计学意义(P＜0.05),治疗组患者的CD4+T细胞及IL-2下降程度不如对照组患者明显,且恢复较快,两组间差异有统计学意义(P＜0.05).结论:胃肠道肿瘤患者在麻醉手术后其细胞免疫功能受到不同程度的抑制,但复合麻醉较单纯全麻的免疫抑制效应低且恢复较快.     

Cutaneous and subcutaneous blood flow during general anaesthesia

The vasodilator effect of anaesthetic agents on cutaneous vessels has often been investigated. In contrast, although subcutaneous tissue is concerned with metabolism and thermoregulation, the effects of anaesthesia on subcutaneous blood flow have not been well documented. The purpose of this study was to determine the magnitude of changes in cutaneous and subcutaneous blood flow during general anaesthesia in Man. Anaesthesia was induced with flunitrazepam in 15 patients before facial plastic surgery. Blood flow was estimated using heat thermal clearance (HC). Two HC sensors in different areas allowed the measurement of superficial and deep HC. Systolic (SABP), diastolic (DABP) and mean arterial blood pressure (MABP), heart rate (HR), and rectal and mean skin temperature were also recorded. After induction of anaesthesia, HR increased significantly (p less than 0.05) whereas SABP, DABP and MABP remained unchanged. The rectal-toe temperature gradient fell from 6.3 +/- 4.1 degrees C to 3.4 +/- 1.1 degrees C (p less than 0.01) suggesting a reduction in vasomotor tone. Superficial HC increased from 0.37 +/- 0.06 to 0.42 +/- 0.08 W.m-1.degrees C-1 (p less than 0.05) whereas deep HC decreased from 0.33 +/- 0.07 to 0.31 +/- 0.09 W.m-1.degrees C-1 (NS) and returned to the control value thereafter. Rectal temperature and mean skin temperature were unchanged. The changes in deep HC are similar to those previously observed in muscle during induction of anaesthesia. Our results show that anaesthesia mainly affects cutaneous blood flow, without any significant change in subcutaneous blood flow during the early phase of anaesthesia in human beings.     

全身麻醉复合硬膜外麻醉与全身麻醉对老年腹部肿瘤手术患者的影响

目的:探究全身麻醉复合硬膜外麻醉与全身麻醉对老年腹部肿瘤手术患者影响。方法:选择2015年10月-2018年10月于我院进行手术治疗的老年腹部肿瘤患者96例,随机分为两组,每组48例患者。其中,对照组患者给予全身麻醉,研究组患者联合硬膜外麻醉,对比两组患者的麻醉指标、围术期指标、应激激素指标、肺功能指标和不同时间点血清NSE、S100β浓度的变化。结果:研究组患者的瑞芬太尼用量、异丙酚用量、苏醒时间、拔管时间均显著少于(短于)对照组(P<0.05);对照组患者术后肾上腺素、去甲肾上腺素、皮质醇等指标水平均比术前显著升高(P<0.05);研究组患者术后的去甲肾上腺素水平显著高于术前(P<0.05),但肾上腺素、皮质醇与术前无显著性差异(P<0.05);随着治疗时间推移,两组患者手术1 h时、手术时2 h时、术毕时血清NSE、S100β浓度呈逐渐升高趋势,且研究组患者以上指标均明显低于对照组(P<0.05);对照组患者术后的(MVV-VE)/FEV1、MVV/FEV1指标水平均比术前显著降低(P<0.05);RV/TLC水平比术前显著升高(P<0.05);但研究组患者术后的(MVV-VE)/FEV1、MVV/FEV1、RV/TLC等指标与术前无显著差异(P>0.05)。结论:与全身麻醉相比,全身麻醉复合硬膜外麻醉可更有效改善老年腹部肿瘤患者手术指标,并控制机体应激反应和降低麻醉过程对脑部的损伤,且对其肺功能影响较小。     

Reproductive hormone secretion and testicular growth in bull calves actively immunized against testosterone and oestradiol-17 beta

Groups of bull calves received a primary immunization against testosterone (Group T; N = 7) or oestradiol-17 beta (Group E; N = 9) at 3 months of age and booster injections on four occasions at approximately 2 month intervals. Controls (Group C, N = 7) were immunized against human serum albumin alone using the same protocol. Immunity was achieved against both steroids as judged by the secondary antisteroid antibody titres in Group T (730 +/- 231; reciprocal of titre) and Group E (12,205 +/- 4366) bulls; however, peak antibody titres generally declined with successive booster injections. Mean plasma concentrations of LH, FSH and testosterone during the period from 3 to 10 months of age were higher (P less than 0.05) in Group T bulls than in Groups C and E. Group T bulls had larger testes compared with controls from 6 months of age onwards. At castration at 14 months of age, testes of Group T bulls were heavier (P less than 0.05) than those of Groups C and E (179 +/- 13, 145 +/- 8 and 147 +/- 6 g, respectively). At 10 months of age, there were no differences among treatment groups in LH responses to LHRH, but the testosterone responses were greater (P less than 0.05) in bulls in Group T (26.2 +/- 4.9 ng/ml) and Group E (16.6 +/- 1.8 ng/ml) compared with those in Group C (6.9 +/- 0.6 ng/ml). Testosterone responses to hCG determined at 13 months of age were also greater (P less than 0.05) in Groups T and E relative to controls. At 14 months of age daily sperm production rates per bull (X 10(-9)) were higher (P less than 0.10) in Group T bulls (2.2 +/- 0.1) than those in Groups C (1.6 +/- 0.2) and E (1.6 +/- 0.1). These results indicate that early immunity against testosterone is associated with increased gonadotrophin secretion and accelerated growth of the testes in prepubertal bulls. Also, chronic immunity against testosterone or oestradiol-17 beta enhances the steroidogenic response of bull testes to gonadotrophic stimulation. If the above responses observed in young bulls are shown to be sustained, then immunity against gonadal steroids early in life may confer some reproductive advantage in mature animals.     

Effects of ACTH on plasma levels of adrenal steroids in essential hypertension.

Plasma concentrations of progesterone (P), deoxycorticosterone (DOC), 17-hydroxyprogesterone (17-OH P), corticosterone (B), deoxycortisol (S), cortisol (F) and aldosterone (A) in 8 control subjects (mean age: 40.5 years) and 10 patients with essential hypertension (EH) (mean age: 48.5 years) were determined before, 4 and 8 hours after an infusion of ACTH at a rate of 25 units per 8 hours. Secretion rates (SR) of 18-hydroxy-11-deoxycorticosterone (18-OH DOC) were measured 24 hours before and again on the day of ACTH infusion. All subjects were studied on the fourth day of a diet containing 135 mEq of sodium and 90 mEq of potassium. There was no statistically significant difference between 8 control subjects and 10 patients with EH in the 7 plasma steroid levels and the SR of 18-OH DOC before ACTH infusion. The mean plasma P response to ACTH was slightly lower in controls than in patients with EH, while that of 17-OH P (in male subjects) was slightly higher. The mean plasma B response was significantly lower after 4 hours of ACTH infusion (p less than 0.01), while that of DOC was significantly higher after 8 hours of ACTH infusion (p less than 0.05) in patients with EH. The mean plasma S rose significantly more in patients with EH (p less than 0.025) at 4 and 8 hours after ACTH infusion. The mean plasma F response to ACTH infusion was slightly lower in patients with EH than in controls. The mean response of 18-OH DOC SR to ACTH infusion was slightly higher in patients with EH than in controls. The mean plasma A response was significantly higher in patients with EH than in controls 4 (p less than 0.05) and 8 hour (p less than 0.001) after an ACTH infusion. These results could be explained in part by abnormalities in the 17- and 11-hydroxylase systems, and that the abnormality in 11-hydroxylation was more pronounced than that in the 17-position. Furthermore, we suspect that the sensitivity of adrenal aldosterone to ACTH might be increased or another accelerated pathway to aldosterone biosynthesis might exist in patients with EH.     

Increase of IGF I binding to erythrocyte receptors during the TRH-test: correlation between IGF I binding and thyroid hormone values

The effects of TRH on insulin-like growth factor I receptors were investigated on erythrocytes from 7 GH-deficient children having plasma GH levels less than 10 ng/ml during two provocation tests. Intravenous injection of synthetic TRH (0.2 mg/m2) was followed by a marked increase of IGF I binding on erythrocytes, from 3.9% +/- 0.3% to 5.9% +/- 0.3% (P less than 0.005) after 1 hour and 7.3% +/- 0.4% (P less than 0.005) after 2 hours. The IGF I binding variations were due to an increase in both the receptor affinity and the number of sites. The levels of plasma GH, IGF I, T3, T4, free T4, TSH and prolactin having been determined during the TRH test at 0, 1 hour, and 2 hours after the injection, the increase in the IGF I binding to erythrocytes at the same time correlated with the rise of thyroid hormones: triiodothyronine T3 (P less than 0.001) and thyroxine T4 (P less than 0.005) and not with the level of the other hormones. These findings suggest that thyroid hormones play a role in the regulation of insulin-like growth factor I receptors.     

糖尿病患者外科手术麻醉的相关多态性及Logistic分析

目的：研究与探讨糖尿病患者外科手术麻醉的安全性和有效性。方法：糖尿病外科手术患堵262例,采用腰一硬联合麻醉146例,全身麻醉116例。结果：表明腰一硬联合麻醉组在术中血糖均值水平、胰岛素的平均使用剂量均少于全身麻醉组,有统计学意义（p〈0．05）。腰．硬联合麻醉组麻醉后空腹血糖、餐后血糖、糖化血红蛋白水平增高幅度均小于全身麻醉组,（P〈0．05）。通过用Logistic回归方程分析影响糖尿病患者麻醉效果的因素除性别无显著相关性,年龄、糖尿病病程、吸烟、饮酒、体重指数均与麻醉效果有高度相关性（正相关）。结论：糖尿病手术患者采用腰．硬联合麻醉效果较好。     

Circadian changes in serum concentrations of steroids in Japanese char Salvelinus leucomaenis at the stage of final maturation

Circadian changes in serum concentrations of testosterone (T), 11-ketotestosterone (11KT), estradiol-17beta (E2), 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP), 17alpha-hydroxyprogesterone (OHP), cortisol (F) and progesterone (P) were investigated in the spermiated/ovulated Japanese char Salvelinus leucomaenis for over three days using newly developed time-resolved fluoroimmunoassays. Testosterone and DHP in both sex and 11KT in male showed significantly (P<0.05) higher serum levels just before/after onset of darkness (15:00 or 18:00), and the levels during night and daytime were significantly (P<0.05) lower than those of the peak levels. Serum F levels in both sex during dark phase were significantly (P<0.05) higher than those levels during daytime. A surge of serum OHP concentrations in both sexes was observed at the time of twilight (03:00). The peak time of serum T, 11KT and DHP levels were approximately 6 hours prior to those of serum F and OHP levels. Serum E2 in female and P in both sex fluctuated intensely during sampling period, and did not show remarkable changes. These results strongly suggest the existence of circadian-like diel changes in serum T, DHP, F and OHP levels in both sex and 11KT in male, and no variations in serum E2 in female and P in both sex in spermiated/ovulated Japanese char under the stage of final maturation. Furthermore, relationship between circadian rhythms of steroid hormones and spawning behaviors are discussed in the present study.     

Amplification of nocturnal oscillations in PRA and aldosterone during continuous heat exposure

To assess the effect of continuous heat exposure on the nocturnal patterns of renin, aldosterone, adrenocorticotropic hormone (ACTH), and cortisol, six young men were exposed to thermoneutral environment for 5 days, followed by a 5-day acclimation period in a hot dry environment (35 degrees C). Blood was collected at 10-min intervals during the second night at thermoneutrality (N0) and during the first (N1) and the last (N5) nights of heat exposure. Polygraphic recordings of sleep were scored according to established criteria. Continuous heat exposure led to progressive decreases in the 24-h urinary volume and in Na excretion, whereas urinary osmolality increased. After 5 days of uninterrupted heat, significant increases were found in plasma volume (P less than 0.05), osmolality (P less than 0.01), plasma Na (P less than 0.01), and protein levels (P less than 0.05). Sweat gland output increased during the first 3 days and then declined without any concomitant increases in body temperature. Compared with N0, there were no differences in plasma renin activity (PRA) and aldosterone (PA) profiles during N1 at 35 degrees C. However, during N5 the mean PRA and PA levels were significantly (P less than 0.05) enhanced, and their nocturnal oscillations were amplified (P less than 0.05). This amplification occurred mainly in the second part of the night when regular rapid-eye-movement and non-rapid-eye-movement sleep cycles were observed, leading to a general upward trend in the nocturnal profiles. The relationship between the nocturnal PRA oscillations and the sleep cycles was not modified. ACTH and cortisol patterns were not affected by continuous heat exposure.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of stanozolol and boldenone undecylenate on plasma testosterone and gonadotropins and on testis histology in pony stallions

Fifty 2- to 16- yr old pony stallions were randomly assigned to one of five treatments: Group 1, controls (no treatment); Group 2, 0.55 mg/kg stanozolol weekly for 13 treatments; Group 3, 1.1 mg/kg stanozolol every 3 wk for 5 treatments; Group 4, 1.1 mg/kg boldenone undecylenate every 3 wk for 5 treatments; and Group 5, 0.55 boldenone undecylenate weekly for 13 treatments. Mean plasma testosterone levels for Groups 2, 4, and 5 were elevated over controls (P < 0.01) at 2, 8, and 9 wk, respectively. Testosterone levels for ponies in Group 3 did not differ from controls (P > 0.05). There were no differences in mean plasma luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels among groups (P > 0.05). Daily spermatid production per gram of testicular parenchyma (DSP/gm) in Group 5 was lower than in controls (P < 0.05), whereas DSP/gm was not different among groups 1 to 4 (P > 0.05). There were no differences among groups (P > 0.05) in the percentage of Stage 8 tubules or relative number of Leydig cells. The mean diameter of Leydig cells was less for Group 5 than for controls (P < 0.05), but was not different for Groups 1 to 3 (P > 0.05).     

Opioidergic control of gonadotrophin secretion in the prepubertal gilt during restricted feeding and realimentation

Prepubertal gilts, having undergone a 7-day period of feed restriction to a maintenance ration, were allocated to one of 4 treatments; restricted feeding at 09:00 and 17:00 h for an 8th day both with (Group RN) and without (Group R) administration of the opioid antagonist naloxone hydrochloride (1 mg.kg-1 at 09:30 h followed by 0.5 mg.kg-1 at hourly intervals for 7 h), or feed to appetite with (Group ALN) and without (Group AL) naloxone administration. Gilts were bled at 10-min intervals on Day 8 from morning to evening feed and plasma LH, FSH and prolactin concentrations were measured by radioimmunoassay. Compared with Group R gilts, Group AL gilts exhibited significantly (P less than or equal to 0.05) higher mean and maximum LH concentrations and pulsatility, lower prolactin concentrations (P less than 0.05) but no significant difference in FSH secretion. Naloxone significantly depressed the increase in LH after re-feeding (Group ALN) (P less than 0.05). Once again there were no significant effects on FSH secretion. Naloxone also significantly depressed prolactin secretion in feed-restricted gilts (P less than 0.05). These results confirm that re-feeding of feed-restricted prepubertal gilts stimulates an immediate increase in LH secretion and that this elevation is not mediated via a suppression of inhibitory endogenous opioidergic tone. Rather, naloxone treatment appeared to expose a latent inhibition of LH secretion. The control of LH secretion is distinct from that of FSH in this model.     

Postpartum Reproductive Performance in Dairy Cows in Relation to Phosphorus Status

The levels of inorganic phosphorus in blood samples from two cow populations were related to reproductive performance. Group I comprised 305 dairy cows from 17 herds with normal fertility. The herds were visited every 2–4 weeks. Blood samples were collected from animals between 4 weeks prior to expected calving and subsequent confirmed pregnancy. The individual mean plasma phosphorus level in samples collected from 0–90 days after calving in cows which conceived following insemination (n = 262) was related to reproductive performance. Group II comprised cows from 47 herds with reproductive problems. The herds were visited once during the indoor season for blood sampling. Mean herd serum phosphorus levels were related to herd reproductive performance registered during a period from 6 months before to 9 months after the time of blood sampling. Overall mean herd phosphorus levels were 1.51 ± 0.08 mmol/1 plasma (±SD) (Group I) and 1.77 ± 0.16 mmol/1 serum (±SD) (Group II). In Group I (indivu-dual cows), the coefficient of correlation between phosphorus levels and elapsed time from calving to pregnancy was low (r = 0.10, p<0.1). In Group II (herds) significant correlations were observed between the fertility status index (FS), the average number of days from calving to last insemination and phosphorus levels (rs = 0.32, P <0.05 and rs p <0.05, respectively). The mean herd phosphorus levels were within normal limits in both groups. Although increased phosphorus levels were associated with lower fertility in both groups, the amount of the total fertility variation which could be explained by phosphorus levels was small.     

Relationship of liver and skeletal muscle IGF-1 mRNA to plasma GH profile, production of IGF-1 by liver, plasma IGF-1 concentrations, and growth rates of cattle

Growth hormone (GH), insulin-like growth factor-1 (IGF-1), and thyroid hormone (T3 and T4) concentrations in blood plasma of 18 crossbred cattle (six bulls, six steers, and six heifers) were measured over an 8-hr period. One week later at slaughter, IGF-1 production by liver slices and IGF-1 mRNA concentrations in skeletal muscle and liver were measured. Bulls had higher (P less than 0.05) mean plasma GH and GH peak amplitudes (P less than 0.01) than heifers, and values for steers were intermediate between bulls and heifers. Baseline GH concentrations and number of GH peaks were not significantly different for the three groups. Bulls had 1.6-fold (P less than 0.01) and 3.0-fold (P less than 0.01) greater liver IGF-1 mRNA concentrations than steers or heifers, respectively, whereas the steers had 1.8-fold (P less than 0.05) greater IGF-1 mRNA in liver than heifers. Production of IGF-1 by liver slices was greater (P less than 0.05) in bulls than steers or heifers. Bulls had 1.3-fold greater plasma IGF-1 than steers (P less than 0.01), whereas steers had 1.8-fold greater plasma IGF-1 than heifers (P less than 0.01). There were no significant differences in concentrations of skeletal muscle IGF-1 mRNA between the three groups of animals. Liver IGF-1 mRNA, liver IGF-1 production, and plasma IGF-1 were all significantly correlated with gain and mean GH peak amplitude, but not with GH baseline, GH peak frequency, or concentrations of T3 and T4. Concentrations if IGF-1 mRNA in skeletal muscle were not correlated to gain or any parameter of the GH profile. Plasma concentrations of T3 were significantly (P less than 0.05) negatively correlated to plasma GH baseline concentrations. Muscle IGF-1 mRNA concentration was negatively related to plasma T4 and T3. The results of this study suggest that the cascade of events starting with secretion of GH from the pituitary, expression of liver IGF-1 mRNA, and secretion of IGF-1 by the liver are important phenomena for growth of cattle.     

Control of gonadotrophin release in Scottish Blackface and Finnish Landrace ewes during seasonal anoestrus

The patterns of LH and FSH secretion were measured in 4 experimental groups of Finnish Landrace and Scottish Blackface ewes: long-term (18 months) ovariectomized ewes (Group 1), long-term ovariectomized ewes with an oestradiol implant, which has been shown to produce peripheral levels of approximately 5 pg/ml (Group 2), long-term ovariectomized ewes with an oestradiol implant for 18 months which was subsequently removed (surgery on Day 0) (Group 3) and short-term ovariectomized ewes (surgery on Day 0) (Group 4). LH and FSH concentrations were monitored in all groups at approximately weekly intervals, before and after Day 0. Finnish Landrace ewes in Groups 1, 2 and 3 had significantly higher mean FSH concentrations than did Scottish Blackface ewes (P less than 0.01). FSH and LH concentrations increased significantly in Groups 3 and 4, but values in Group 4 were significantly lower (P less than 0.01) than those in Group 1 ewes even up to 30 days after ovariectomy. In Group 3, LH concentrations increased to levels similar to those in Group 1. The pattern of LH release was, however, significantly different, with a lower LH pulse frequency (P less than 0.05), but higher pulse amplitude (P less than 0.05). This difference was maintained at least until 28 days after implant removal. We suggest that removal of negative feedback by ovariectomy demonstrates an underlying breed difference in the pattern of FSH secretion and that ovarian factors other than oestradiol are also involved in the negative-feedback control of hypothalamic/pituitary gland function. Furthermore, negative-feedback effects can be maintained for long periods, at least 28 days, after ovariectomy or oestradiol implant removal.     

Peroxisome proliferator-activated receptor-delta polymorphisms are associated with physical performance and plasma lipids: the HERITAGE Family Study

We tested the hypothesis that peroxisome proliferator-activated receptor-delta (PPARdelta) gene polymorphisms are associated with cardiorespiratory fitness and plasma lipid responses to endurance training. Associations between the PPARdelta exon 4 +15 C/T and exon 7 +65 A/G polymorphisms and maximal exercise capacity and plasma lipid responses to 20 wk of endurance training were investigated in healthy white (n = 477) and black (n = 264) subjects. In black subjects, the exon 4 +15 C/C homozygotes showed a smaller training-induced increase in maximal oxygen consumption (P = 0.028) than the C/T and T/T genotypes. Similarly, a lower training response in maximal power output was observed in the exon 4 +15 C/C homozygotes (P = 0.005) compared with the heterozygotes and the T/T homozygotes in black subjects, and a similar trend was evident in white subjects (P = 0.087). In white subjects, baseline apolipoprotein A-1 (Apo A-1)levels were higher in the exon 4 +15 C/C (P = 0.011) and exon 7 +65 G/G (P = 0.05) genotypes compared with those in the other genotypes. In white subjects, exon 4 +15 C/C (P = 0.0025) and exon 7 +65 G/G (P = 0.011) genotypes showed significantly greater increases in plasma high-density lipoprotein-cholesterol (HDL-C) levels with endurance training than in the other genotypes, whereas in black subjects the exon 4 +15 CC homozygotes tended to increase (P = 0.057) their Apo A-1 levels more than the T allele carriers. DNA sequence variation in the PPARdelta locus is a potential modifier of changes in cardiorespiratory fitness and plasma HDL-C in healthy individuals in response to regular exercise.