Determinants of estimated insulin resistance and beta-cell function in Indian, Creole and Chinese Mauritians. The Mauritius NCD Study Group

Associations with insulin resistance and islet beta-cell function have been studied cross-sectionally in a population-based sample of 4278 Mauritians comprising Asian Indian, Creole and Chinese subjects. Insulin resistance and beta-cell function were estimated by a computer solved model based on fasting plasma glucose and insulin concentrations. Insulin resistance increased with declining glucose tolerance, whereas beta-cell function was highest in subjects with impaired glucose tolerance (IGT) and lowest in those with non-insulin-dependent diabetes mellitus (NIDDM). Indian subjects had the highest beta-cell function, while ethnic differences in insulin sensitivity were less marked. This may indicate that deranged beta-cell function rather than insulin resistance is the primary determinant of hyperinsulinaemia and glucose intolerance in Asian Indians. beta-Cell function declined with age more sharply than did insulin sensitivity, suggesting that the age-related decline in glucose tolerance is primarily related to loss of beta-cell function. Body mass index, waist/hip ratio, physical inactivity and female sex were independently associated with insulin resistance and beta-cell function. Subjects with a family history of diabetes had increased insulin resistance, irrespective of glucose tolerance. This or similar models may have application in longitudinal population-based studies which seek to determine the relative contributions of insulin resistance and beta-cell function to the aetio-pathogenesis of NIDDM.     

Short-term effects of growth hormone on fuel oxidation and regional substrate metabolism in normal man

Primarily by increasing the availability of lipid intermediates, GH is likely to have profound effects on substrate consumption rates. To examine the short term actions of GH on glucose turnover, fuel oxidation and regional forearm metabolism, six normal volunteers were each studied twice for 5.5 h after having received a 4-h infusion of GH (20 ng/kg.min) or saline. GH induced slightly falling plasma glucose levels, acute 40-50% decreases in forearm glucose uptake, and no change in glucose turnover. Furthermore, substantial increases in circulating concentrations and forearm uptake of nonesterified fatty acids and 3-hydroxybutyrate were recorded. Although GH infusion was followed by a 50% reduction of forearm alanine release hepatic nitrogen excretion seemed unaffected. Energy expenditure was not influenced by GH, but the non-protein respiratory exchange ratio decreased from a basal value of 0.778 +/- 0.008 to 0.732 +/- 0.007 after GH treatment (P less than 0.05). Correspondingly, lipid oxidation increased from 1.20 +/- 0.06 to 1.48 +/- 0.09 mg/kg.min, and glucose oxidation decreased from 0.97 +/- 0.12 to 0.39 +/- 0.06 mg/kg.min (P less than 0.05). Nonoxidative glucose utilization tended to increase. These data indicate that GH, by promoting lipid utilization and decreasing glucose oxidation, diminishes the need for gluconeogenesis and, therefore, could be protein preserving in the long term. Overall, we found no evidence of GH having acute insulin-like effects on glucose metabolism. GH appears to increase glucose storage, leaving total energy expenditure unaffected.     

Conserved enzymes mediate the early reactions of carotenoid biosynthesis in nonphotosynthetic and photosynthetic prokaryotes.

Carotenoids comprise one of the most widespread classes of pigments found in nature. The first reactions of C40 carotenoid biosynthesis proceed through common intermediates in all organisms, suggesting the evolutionary conservation of early enzymes from this pathway. We report here the nucleotide sequence of three genes from the carotenoid biosynthesis gene cluster of Erwinia herbicola, a nonphotosynthetic epiphytic bacterium, which encode homologs of the CrtB, CrtE, and CrtI proteins of Rhodobacter capsulatus, a purple nonsulfur photosynthetic bacterium. CrtB (prephytoene pyrophosphate synthase), CrtE (phytoene synthase), and CrtI (phytoene dehydrogenase) are required for the first three reactions specific to the carotenoid branch of general isoprenoid metabolism. The homologous proteins from E. herbicola and R. capsulatus show sequence identities of 41.7% for CrtI, 33.7% for CrtB, and 30.8% for CrtE. E. herbicola and R. capsulatus CrtI also display 27.2% and 27.9% sequence identity, respectively, with R. capsulatus CrtD (methoxyneurosporene dehydrogenase). All three dehydrogenases possess a hydrophobic N-terminal domain containing a putative ADP-binding beta alpha beta fold characteristic of enzymes known to bind FAD or NAD(P) cofactors. In addition, E. herbicola and R. capsulatus CrtB show 25.2% and 23.3% respective sequence identities with the protein product of pTOM5, a tomato cDNA of unknown function that is differentially expressed during fruit ripening. These data indicate the structural conservation of early carotenoid biosynthesis enzymes in evolutionarily diverse organisms.     

Improvement in glucose tolerance after one year of follow-up in a Hindu community in Africa

Oral glucose tolerance was studied following a 75 g glucose load in 108 (82.4%) of 131 male and 110 (79.1%) of 139 female members of a Hindu subcommunity aged 15 years and over in Dar es Salaam. One year later, the glucose tolerance tests were repeated in 93 (86.1%) and 93 (84.5%) of the 108 male, and 110 of the female subjects, respectively. In the first survey, 25 (26.9%) of the 93 male and 24 (25.8%) of the 93 female subjects had impaired glucose tolerance (IGT), 6 (6.4%) and 15 (16.1%), respectively, had diabetes mellitus; and 62 (66.7%) and 54 (58.1%), respectively, had normal glucose tolerance. In the repeat survey, of the 93 male and 93 female subjects, 8 (8.6%) and 7 (7.5%) had IGT, 4 (4.3%) and 10 (10.8%) had diabetes; and 81 (87.1%) and 76 (81.7%) were normal, respectively. Of the 21 subjects diagnosed as having diabetes in the first survey, 13 (61.9%) continued to show diabetic glucose tolerance; 4 (19%) IGT and 4 (19%) had normal glucose tolerance with no gender difference. One (1.6%) of the 62 male subjects and none of the 54 females with normal glucose tolerance in the first survey progressed to IGT, while the remainder retained normal glucose tolerance. Diabetes and IGT rates in both surveys were higher for the older than the younger persons. A significant fall in mean fasting and post-75 g blood glucose levels, and in mean systolic and diastolic pressure levels was observed between the first and second surveys in both genders. There was, however, no significant difference in body mass index (BMI), serum total cholesterol and triglyceride levels between surveys, suggesting that major dietary changes had not taken place. Male subjects who showed persistent IGT had significantly lower mean level of body mass index (kg/m²) than subjects who reverted to normal, whilst for the whole group those who had persistent IGT were older. It is tempting to speculate that these changes were due to community action. However, in view of the lack of change in weight and lipids and similar results in other communities in Tanzania when retested at 1 week, further studies are needed to establish the significance of the findings.     

Jump Rope Training: Balance and Motor Coordination in Preadolescent Soccer Players

General physical practice and multidimensional exercises are essential elements that allow young athletes to enhance their coordinative traits, balance, and strength and power levels, which are linked to the learning soccer-specific skills. Jumping rope is a widely-used and non-specific practical method for the development of athletic conditioning, balance and coordination in several disciplines. Thus, the aim of this study was to investigate the effects of a short-term training protocol including jumping rope (JR) exercises on motor abilities and body balance in young soccer players. Twenty-four preadolescent soccer players were recruited and placed in two different groups. In the Experimental group (EG), children performed JR training at the beginning of the training session. The control group (CG), executed soccer specific drills. Harre circuit test (HCT) and Lower Quarter Y balance test (YBT-LQ) were selected to evaluate participant’s motor ability (e.g. ability to perform rapidly a course with different physical tasks such as somersault and passages above/below obstacles ) and to assess unilateral dynamic lower limb balance after 8 weeks of training. Statistical analysis consisted of paired t-test and mixed analysis of variance scores to determine any significant interactions. Children who performed jumping rope exercises showed a significant decrease of 9% (p < 0.01, ES = 0.50-0.80) in the performance time of HCT. With regard to the CG, no differences were highlighted (p > 0.05, ES = 0.05-0.2) from pre- to post-training. A training-by-group interaction was found for the composite score in both legs (p < 0.05, Part η² > 0.14). Our findings demonstrated that JR practice within regular soccer training enhanced general motor coordination and balance in preadolescent soccer players. Therefore, the inclusion of JR practice within regular soccer training session should encouraged to improve children’s motor skills.

Key points

• Performing jumping rope exercises within a regular soccer program can be an additional method to improve balance and motor coordination.
• The performance improvement in the Harre Circuit Test associated with jump rope training can potentially be attributed to an enhancement of the inter-limb coordination and SSC ability.
• Results from the present study indicate that young soccer players should be encouraged to practice general physical activities together with sport-specific exercise during their training sessions.

Key words: Muscle power, plyometric exercise, postural control, motor skills, deliberate practice     

Hypoandrogenism related to early skin wound healing resistance in rats

The purpose of this study was to verify the effect of testosterone depletion on healing of surgical skin wounds at different ages and post‐operative periods. Forty‐four Wistar male rats were divided into four groups: Group 1Y (n = 11) – young control, sham‐operated rats (30‐day old); Group 1A (n = 10) – adult control, sham‐operated rats (3 to 4‐month old); Group 2Y (n = 10) – young rats after bilateral orchiectomy; and Group 2A (n = 11) – adult rats after bilateral orchiectomy. After 6 months, a linear incision was performed on the dorsal region of the animals. The resistance of the wound healing was measured in a skin fragment using a tensiometer, on the 7th and 21st post‐operative days. The wound healing resistance was higher in Group 1Y than in Group 2Y after 7 days (P < 0.05). Wound healing resistance at 21 days was higher than at 7 days in all groups (P < 0.05). Late wound healing resistance was not different between young and adult rats. It is concluded that bilateral orchiectomy diminished the wound healing resistance only in young animals at the 7th post‐operative day.     

Impact of pulmonary metastases of the R1H-tumour on radiation tolerance of rat lung

Purpose : The aim was to investigate the influence of pulmonary metastases of the rhabdomyosarcoma R1H on the radiation response of the lung of the WAG/Rij rat. Material and methods : Three groups of animals were investigated: metastases-free animals treated with fractionated irradiation of the lungs; metastases-bearing animals receiving no irradiation; and metastases-bearing animals treated with fractionated irradiation initiated 14, 21 or 28 days after induction of pulmonary metastases of the R1H-tumour by i.v. injection of viable tumour cells. Metastases were thus treated at various well-defined sizes. Total doses of 20-60Gy were applied in fractions of 2 Gy within 11 days. Complication rate and survival time were used as endpoints. Results : About 2 months after onset of irradiation treatment, animals had to be sacrificed because of severe respiratory distress either caused by irradiation-induced lung damage (median 57 days, range 36-77 days), or because of development of lung metastases (65, 20-160 days). A decrease of the ED 50 (dose required to induce lethal lung damage in 50% of irradiated animals) was determined for metastases-bearing animals. This effect increased with metastatic volume. Conclusions : The results suggest that the presence of tumours in the lung decreased the lung tolerance to radiation. This effect can hardly be explained by a reduction in functional lung volume by metastatic volume.     

Biomechanics and predicted energetics of sprinting on sand: Hints for soccer training

ObjectivesThe purpose of this study was to analyse energetic and biomechanical parameters of sprinting on sand surface, aimed at the evaluation of inherent aspects of soccer training programs, injury prevention and recovery processes.DesignTwenty-nine professional soccer players took part in this study: they performed maximal sprints and maximal shuttle sprints on a 12 m distance on natural grass, artificial turf and soft, dry sand.MethodsSpeed, acceleration, deceleration, stride length, stride frequency, flight and contact time, estimated energy cost, metabolic and mechanical power, efficiency and stiffness values, have been calculated through the instrument SPI-Pro (GPSports, Canberra, Australia) supported by two fixed cameras.ResultsThe comparison between values recorded on sand with those recorded on natural or artificial grass has highlighted significant decreases (p < 0.001) of speed, acceleration, stride length, flight time and mechanical power, efficiency and stiffness. Contact time, energy cost, metabolic power (p < 0.001) and deceleration (p < 0.05) were higher on sand whereas no significant differences were found regarding stride frequency (p > 0.05).ConclusionsThese results show that on sand it is possible to perform maximal intensity sprints with higher energy expenditure and metabolic power values, without reaching maximum speed and with smaller impact shocks. Furthermore, exercises with change of direction carried out on this surface allow to reach higher deceleration values. In addition, sprinting on sand potentially entails a limited stretch of the involved muscles. It can therefore offer a valid alternative to traditional training, injury prevention and rehabilitation programs.     

Study of immunohistochemical expression of insulin-like growth factor I and proliferating cell nuclear antigen in thyroid gland papillary carcinoma and its metastasis

BACKGROUND: Several tumor factors are associated with papillary thyroid cancer. Most studies do not compare the expressions of these factors in the primary tumors and in their associated cervical metastasis. METHODS: Paraffin sections of 20 patients with papillary carcinoma of the thyroid gland with lymph node metastasis were studied. The presence and distribution of insulin-like growth factor I (IGF-I) and proliferating cell nuclear antigen (PCNA) was analyzed, through immunohistochemical technique, in both primaries and lymph node metastasis. The results were correlated with clinical-pathologic data (sex, age, size of primary, multicentricity, thyroid capsule invasion, lymphatic and blood vessels invasion, development of distant metastasis, and associated thyroid diseases). RESULTS: The qualitative analysis showed the reaction for IGF-I was present in more than 90% of the neoplastic cells in both primaries and lymph node metastasis. No correlation with the clinical-pathological features was observed. Regarding the PCNA, the mean percentage of nuclei stained showed no statistical difference between primaries and metastasis (p = 0.598). Except for age, clinicopathologic data had no influence on the mean percentage of nuclei stained. A correlation was verified between the percentage of cells stained by PCNA in primary tumors and the patients' age (p < 0. 01). CONCLUSIONS: The expressions of these tumor factors are equally intense for both primary and metastatic tissue in papillary thyroid cancer. Despite the small size of the sample, the expressions of IGF-I and PCNA could not be associated to clinical-pathologic features, except for the age. As patients over 40 years old had higher expression of PCNA, this marker may have prognostic significance for patients with papillary thyroid cancer.