The effect of physical exercise on postpartum fitness, hormone and lipid levels: a randomized controlled trial in primiparous, lactating women.

PURPOSE: To evaluate the effect of an exercise training program combining low-impact dance aerobic, resistance and stretching exercise on physical fitness, hormone and lipid levels of postpartum, primiparous, lactating women. METHODS: Thirty seven primiparous, lactating women were randomly assigned at 4-6 weeks postpartum to either follow an exercise training program of 50-60 min aerobic, strengthening and stretching exercise, 3 days a week, for 12 weeks (interventional group; n = 20) or no training program at all (control group; n = 17). The following parameters were measured at baseline and 12 weeks later: (1) for evaluation of physical fitness: VO2max, muscular endurance, joint mobility and body fat; (2) for evaluation of the lipidemic profile: triglyceride, total cholesterol, HDL and LDL levels, and (3) levels of hormones associated with lactation: prolactin, estradiol, cortisol, TSH, fT3 and fT4. RESULTS: After completion of the exercise training program, comparisons between the interventional and the control group showed statistically significant mean changes in VO2max (p = 0.003), muscular endurance of the upper extremities (p < 0.001), and the abdomen (p < 0.001), flexibility (p = 0.042), and body fat (p = 0.007). There were no significant differences between the two groups in mean changes of lipid and hormone levels. CONCLUSION: Implementation of a low-impact exercise training program appears to improve physical fitness of postpartum women, while it does not seem to affect lipid levels and lactation-associated hormone levels. Hence, implementation of an exercise training program combining low-impact dance aerobic, resistance and stretching exercise is feasible in postpartum, primiparous, lactating women.

(99m)Tc-sestamibi uptake in rat skeletal muscle and heart: physiological determinants and correlations.

The lipophilic cationic radiotracer (99m)Tc-sestamibi, known to be concentrated within mitochondria, is widely used for myocardial perfusion and to a lesser extent for muscle metabolism imaging. However, the exact distribution pattern in skeletal muscle has not been yet studied in detail. The present study aims to investigate the (99m)Tc-sestamibi uptake in rat skeletal muscle and myocardium in relation to their metabolic characteristics. (99m)Tc-sestamibi was i.v. administered in twenty adult male Wistar rats and uptake, as percent of injected dose per tissue gram (%ID/g), in the myocardium, soleus, extensor digitorum longus and gastrocnemius muscles was assessed 2 h after the injection. Muscle uptake was also correlated with myocardial uptake, muscle weight and body weight. Skeletal muscle (99m)Tc-sestamibi uptake was a small (9-16 %) fraction of that found in myocardium (1.71+/-0.63 %ID/g). Among the three hindlimb muscles considered, the slow-oxidative soleus muscle showed the highest uptake (0.28+/-0.16 %ID/g). Metabolically diverse parts of the gastrocnemius muscle showed different uptake. Skeletal muscle uptake was positively correlated with myocardial uptake and both were negatively correlated with tissue and body weight. Skeletal muscle and myocardium (99m)Tc-sestamibi uptake is related to their metabolic profile. Myocardium, with an exceptional rich mitochondrial concentration, shows much higher (99m)Tc-sestamibi uptake compared to skeletal muscles. Among muscles, uptake is dependent on their mitochondrial content. Evidence of matching exists between myocardial and muscle uptake, and both are size-dependent.

Effect of aerobic training on 99mTc-methoxy isobutyl isonitrile (99mTc-sestamibi) uptake by myocardium and skeletal muscle: implication for noninvasive assessment of muscle metabolic profile.

AIM: The effect of long-term endurance training on skeletal muscle and myocardial uptake of (99m)Tc-sestamibi, a radiopharmaceutical accumulating in the mitochondria, was investigated. METHODS: Twenty-six Wistar rats were divided into a trained (5 days week(-1) endurance running for 14 weeks) and an untrained group. On completion of training, (99m)Tc-sestamibi was administered and, 2 h post-injection, the myocardium and the soleus, extensor digitorum longus (EDL) and medial gastrocnemius (MG) muscles were removed for the measurement of cytochrome c oxidase (CCO) activity and (99m)Tc-sestamibi uptake. Tissue (99m)Tc-sestamibi kinetics was preliminarily studied in 16 other rats for up to 2 h post-injection. RESULTS: Two hours post-injection (99m)Tc-sestamibi uptake was either stable (myocardium) or still rising (skeletal muscles). Both CCO activity and (99m)Tc-sestamibi uptake decreased in the same order (myocardium, soleus, EDL, MG) in the tissues examined. The CCO activity of the EDL and MG muscles was higher (P < 0.05) in the trained compared to the untrained group. (99m)Tc-sestamibi uptake in the soleus and EDL muscles was higher (P < 0.05) in the trained compared to the untrained rats, whereas the difference in MG was marginally significant (P = 0.06) in favour of the trained group. CONCLUSIONS: Long-term endurance training, resulting in elevated skeletal muscle CCO activity, is also associated with a similar increase in (99m)Tc-sestamibi uptake. This finding suggests that (99m)Tc-sestamibi could be used in imaging assessment of skeletal muscle metabolism with possible applications in both clinical and sports medicine settings.

Nurses' ethical decision-making role in artificial nutritional support.

This study provides an insight into the process of ethical decision-making regarding the initiation or withdrawal of artificial nutritional support of seriously ill patients and explores the nursing involvement in it. Fifteen health carers were recruited from a clinical nutrition unit in the UK and qualitative research methods were used to gather data. The findings of the study indicate that nursing contribution to decision-making appeared to be in the 'back room' as the nurses feel that the decisions about difficult ethical dilemmas are 'out of their hands' because of lack of knowledge, experience and confidence. The medical staff and the clinical nurse specialist appear to be primarily responsible for making important decisions. It is clear from the study that to become more effective in the process, nurses need to enhance their knowledge in nutritional support and to develop their practical skills in ethical decision-making through experience and research.

Assessment of brown adipose tissue activity in rats by 99mTc-sestamibi uptake.

Brown adipose tissue (BAT) physiology and imaging have recently attracted considerable attention. BAT is characterized both by enhanced perfusion and increased mitochondrial activity. (99m)Tc-sestamibi is a lipophilic cationic tracer that concentrates in mitochondria. Data on the accumulation of (99m)Tc-sestamibi in BAT are currently lacking. This study investigates the in vivo (99m)Tc-sestamibi uptake in rat BAT. (99m)Tc-sestamibi was administered in male Wistar rats of various age and body size. (99m)Tc-sestamibi uptake was measured in vitro in BAT and white fat (WF) together with cytochrome c oxidase activity. Both (99m)Tc-sestamibi uptake and cytochrome c oxidase activity were higher in BAT than in WF (P<0.05). (99m)Tc-Sestamibi uptake in both BAT and WF was negatively related to body weight (r = -0.96 and -0.89, respectively) as was the BAT/WF uptake ratio (r = -0.85). These data show a higher (99m)Tc-sestamibi uptake in BAT compared to WF, in agreement with the high mitochondrial content and respiratory activity of the former. The strong negative correlation between (99m)Tc-sestamibi uptake in BAT and body weight (negative allometry), is in accordance to increased needs of thermogenesis in smaller animals. Implications of increased (99m)Tc-sestamibi uptake in BAT in radionuclide imaging are also discussed.

A decrease in soleus muscle force generation in rats after downhill running.

The purpose of the present study was to investigate the immediate and 48-hr post-exercise effects of eccentric contraction-biased exercise on the contractile properties of the soleus muscle in situ. Adult male Wistar rats were categorised into sedentary control rats (n = 10), rats studied immediately (n = 10), and rats studied 48 hours after the exercise (n = 10). The exercise protocol consisted of a 90-min intermittent downhill running (-16 degrees, 16 m/min) on a motor-driven treadmill. The contractile properties of the soleus muscle were recorded following i.p. chloral hydrate anaesthesia. Isometric twitch force (Pt), time-to-peak tension (TPT), half-relaxation time (1/2 RT), and tetanic force at stimulation frequencies of 40, 80, and 100 Hz were recorded. A low-frequency muscle fatigue protocol (stimulation at 4 Hz for 5 min) was applied to test for fatigability. The main findings indicated that Pt generation dropped both immediately and 48 hr after the exercise, while tetanic force was partially restored after 48 hr. Exercise-induced E-C coupling failure and contractile machinery disorganisation due to muscle injury are put forward as the main force reduction causes.

beta-Endorphin plasma levels after intravenous administration of GnRH in female rats.

OBJECTIVE: The study investigates the effects of intravenously administered GnRH on plasma beta-endorphin levels in female proestrous rats. STUDY DESIGN: Sixteen adult female proestrous Wistar rats, 220-250 g, were implanted with two indwelling catheters, one intracarotid and one intrajugular. Ten ng GnRH/100 microl distilled water or 100 microl saline (control) were infused in eight animals per group every 20 min from 12:30 to 14:30 h. Blood was withdrawn through the intracarotid catheter just before the initial infusion (12:30 h) and at 14:00, 15:30, 16:30 and 17:30 h for the determination of plasma beta-endorphin levels. The Mann-Whitney test was used for comparison between GnRH-treated and control rats and the Wilcoxon test within each treatment group. RESULTS: beta-Endorphin levels of GnRH-treated rats were not significantly different at any sampling moment neither compared to preinfusion time nor to the corresponding controls. CONCLUSIONS: Intravenously administered GnRH was not sufficient for any possible effect on the secretion of beta-endorphin from rat pituitary and further investigation is needed to demonstrate if a different experimental model would have any significant effect.

Bone mineral density and muscle strength in young men with mental retardation (with and without Down syndrome).

The objective of this study was to compare the bone mineral density (BMD) of men with Down syndrome (DS) to otherwise mentally retarded (MR) men and to investigate whether leg muscle strength of these patients is related to BMD. Two groups with MR (with and without DS) participated in the study, having met the following criteria: similar age, moderate to mild mental retardation, Tanner stage V of sexual development, similar age of beginning to walk, and equal motor activities. The DS group consisted of 8 men 23.9 +/- 4.2 years, and the MR group without DS consisted of 8 men 23.5 +/- 3.6 years. The two groups were compared with 10 sedentary students of the same age range (25.9 +/- 2.9 years) attending our University. The BMD of the 2(nd) to 4(th) lumbar vertebrae was measured in the PA projection and the mean density was expressed as g/cm(2). The isokinetic muscle strength of the right quadriceps femoris and hamstrings muscles was measured on a Cybex II isokinetic dynamometer. The value measured was peak torque at angular velocities at 60, 120, and 300 degrees.sec(-1). The results showed that BMD in DS individuals versus young adults (reference group of the scanner) was lower at the 26% level (T-score - 2.66 +/- 0.29) and significantly lower (P = 0.002) than that of the MR group. Significantly different muscle strength was observed between the DS and non-DS MR group (in quadriceps at 300 degrees.s(-1): P < 0.01, at 120 and 60 degrees. s(-1): P < 0.05; in hamstrings at 300 degrees.s(-1): P < 0.05). Higher differences in muscle strength were found between MR and control men, but no significant difference existed in BMD between them. Bivariate correlation showed that quadriceps strength significantly predicted the BMD in the DS patients. Active lifestyle and increased physical exercise to improve muscular strength should be instituted to avoid the development of osteoporosis in DS patients.

The effect of intraventricularly administered GnRH on plasma beta-endorphin levels of the rat.

This study investigates the effects of intraventricularly administered gonadotropin-releasing hormone (GnRH) on plasma beta-endorphin levels in female proestrous rats. Adult female Wistar rats (220-250 g) were implanted with an indwelling cannula in the third ventricle. Approximately 20 days later, the animals which had established a regular 4-day cycle were implanted with two indwelling catheters, one intracarotid and one intrajugular, on the morning of proestrus. A single injection of 100 ng GnRH dissolved in 5 microliters distilled water or 5 microliters of saline (control) was infused slowly through the cannula in the third ventricle. Blood was withdrawn via the intracarotid catheter just before the infusion (12.30 h) and at 14.00, 15.30, 16.30 and 17.30 h for the determination of plasma beta-endorphin levels. The results indicated that intracerebroventricular infusion of GnRH causes a significant decline of plasma beta-endorphin levels at all time points. It is postulated that GnRH possibly causes desensitization of GnRH receptors, due to the continuous GnRH supply to the pituitary via the blood circulation.

Gonadal function in young women with Down syndrome.

OBJECTIVE: Investigations suggest an increased incidence of gonadal dysfunction in patients with Down syndrome. New features, Alzheimer disease and osteoporosis emerge in these individuals. Therefore, hormonal investigation in persons with Down syndrome is pursued. METHODS: Thirteen females with trisomy 21 (23.65 +/- 3.23 years old) participated in the study. Ultrasound studies were performed to explore the internal genitals. Blood samples were taken for the determination of follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), prolactin (PRL), dehydroepiandrosterone sulfate (DHEA-S), testosterone (T) and 17-hydroxyprogesterone (17-OHP). RESULTS: The patients were at stage V of sexual development. Ultrasonography demonstrated normal uterine and ovarian size and endometrial thickness as well. The ovaries of all patients contained follicles of normal distribution and various sizes. The mean concentrations of FSH, DHEA-S and E2 were normal. The level of PRL was significantly higher than that of the controls, but within the normal lab range. The levels of LH, T and 17-OHP were significantly elevated, compared to those of the control group (P < 0.05, P < 0.01, P < 0.001, respectively). CONCLUSIONS: Our data produce new information on the gonadal function of Down syndrome women. Specific studies on pituitary-gonadal and pituitary-adrenal axis function are needed.

A comparison of the vasopressin response of rats to intraperitoneal and intravenous administration of hypertonic saline, and the effect of opioid and aminergic antagonists.

The vasopressin response of rats to i.p. injection of hypertonic sodium chloride (1.5 mol/l) was compared with that following i.v. infusion of 1.05 mol sodium chloride/l. The two regimes produced a similar vasopressin response in terms of the osmotic threshold, although the slopes of the plot of plasma vasopressin levels against plasma osmolality were not identical. Pretreatment with naloxone and levallorphan increased the resting vasopressin levels and effectively potentiated vasopressin release in response to hypertonic saline by reducing the osmotic threshold for hormone release. Thus, opioid peptides appear to exert an inhibitory effect on vasopressin release under resting and stimulated conditions. The adrenoreceptor antagonists propranolol, phenyoxybenzamine and phentolamine produced a fall in resting vasopressin concentrations while propranolol and phenoxybenzamine potentiated the osmotic release of vasopressin in association with a fall in the osmotic threshold. This would suggest that noradrenergic pathways are excitatory at rest while having an inhibitory effect on the osmotic response. Metoclopramide also produced a fall in resting plasma vasopressin concentrations while increasing the osmotic response. In contrast haloperidol did not affect the vasopressin response.