Intermittent exercise with and without hypoxia improves insulin sensitivity in individuals with type 2 diabetes

CONTEXT

Hypoxia and muscle contraction stimulate glucose transport activity in vitro. Exercise and hypoxia have additive effects on insulin sensitivity in type 2 diabetics (T2D).

OBJECTIVE

The objective of the study was to examine the effectiveness of intermittent exercise with and without hypoxia on acute- and moderate-term glucose kinetics and insulin sensitivity in T2D.

SETTING

The study was conducted at a university research center.

DESIGN, PARTICIPANTS, AND INTERVENTIONS

Eight male T2D patients completed the following: 1) 60 min of continuous exercise at 90% lactate threshold in hypoxia (HyEx60); 2) intermittent exercise at 120% lactate threshold, separated by periods of passive recovery (5:5 min) in hypoxia [Hy5:5; O₂ ∼ 14.7 (0.2)%]; and 3) intermittent exercise (5:5 min) at 120% lactate threshold in normoxia (O₂ ∼ 20.93%).

MAIN OUTCOME MEASURES

Glucose appearance and glucose disappearance, using an adapted non-steady-state one-compartment model were measured. Homeostasis models of insulin resistance (HOMA(IR)), fasting insulin resistance index (FIRI), and β-cell function were calculated 24 and 48 h after exercise conditions.

RESULTS

Glucose disappearance increased from baseline (1.85 mg/kg · min⁻¹) compared with 24 h (2.01 min/kg · min⁻¹) after HyEx60 (P = 0.031). No difference was noted for both Hy5:5 (P = 0.064) and normoxia (P = 0.385). Hy5:5 demonstrated improvements in HOMA(IR) from baseline [d 1, 6.20 (0.40)] when comparisons were made with d 2 [4.83 (0.41)] (P = 0.0013). HOMA(IR) and FIRI improved in the 24 h (HOMA(IR), P = 0.002; FIRI, P = 0.003), remaining reduced 48 h after HyEx60 (HOMA(IR), P = 0.028; and FIRI, P = 0.034).

CONCLUSION

HyEx60 offered the greatest improvements in acute and moderate-term glucose control in T2D. Intermittent exercise stimulated glucose disposal and improved post-exercise insulin resistance, which was enhanced when exercise was combined with hypoxia (Hy5:5). The data suggest a use of hypoxic exercise in treatment of T2D.

Cooling strategies improve intermittent sprint performance in the heat of athletes with tetraplegia

BACKGROUND

Precooling has been shown to enhance performance in repeated sprint exercise in able-bodied subjects in a hot environment. Spinal cord injury causes thermoregulatory impairment with a detrimental effect on performance. This study assessed whether cooling strategies before and during exercise in the heat enhances sprint performance in athletes with tetraplegia.

METHODS

Eight male athletes with tetraplegia performed intermittent arm crank exercise in the heat (32.0 degrees C (0.1 degrees C); humidity, 50% (0.1%)) for a maximum of 60 min or until exhaustion. Trials involved a no-cooling control (CON), precooling (PRE) or cooling during exercise (DUR). Each intermittent sprint protocol consisted of varied periods of passive rest, maximal sprinting and active recovery.

RESULTS

Both PRE and DUR cooling strategies improved the ability of the athletes to repeatedly perform high-intensity sprints, with times to exhaustion (TTE), whereas during the CON trial, athletes demonstrated a reduction in the total number of sprints and TTE (47.2 (10.8), 52.8 (5.8) and 36.2 (9.6) min for CON, PRE and DUR, respectively). Core temperature was significantly higher for CON (37.3 degrees C (0.3 degrees C)) when compared with both PRE and DUR (36.5 degrees C (0.6 degrees C) and 37.0 degrees C (0.5 degrees C), respectively, p<0.01). Ratings of perceived exertion and thermal sensation upon exhaustion or completion were not different.

CONCLUSIONS

Athletes with tetraplegia should use a precooling or during-exercise cooling strategy specific to the characteristics of their sport when exercising in hot conditions.

Whole genome amplification of buccal cytobrush DNA collected for molecular epidemiology studies

When cytobrush buccal cell samples have been collected as a genomic DNA (gDNA) source for an epidemiological study, whole genome amplification (WGA) can be critical to maintain sufficient DNA for genotyping. We evaluated REPLI-g WGA using gDNA from two paired cytobrushes (cytobush 'A' kept in a cell lysis buffer, and 'B' dried and kept at room temperature for 3 days, and frozen until DNA extraction) in a pilot study (n=21), and from 144 samples collected by mail in a breast cancer study. WGA success was assessed as the per cent completion/concordance of STR/SNP genotypes. Locus amplification bias was assessed using quantitative PCR of 23 human loci. The pilot study showed > 98% completion but low genotype concordance between cytobrush wgaDNA and paired blood gDNA (82% and 84% for cytobrushes A and B, respectively). Substantial amplification bias was observed with significantly lower human gDNA amplification from cytobrush B than A. Using cytobrush gDNA samples from the breast cancer study (n =20), an independent laboratory demonstrated that increasing template gDNA to the REPLI-g reaction improved genotype performance for 49 SNPs; however, average completion and concordance remained below 90%. To reduce genotype misclassification when cytobrush wgaDNA is used, inclusion of paired gDNA/wgaDNA and/or duplicate wgaDNA samples is critical to monitor data quality.

Aerobic capacity and peak power output of elite quadriplegic games players

BACKGROUND

Participation in wheelchair sports such as tennis and rugby enables people with quadriplegia to compete both individually and as a team at the highest level. Both sports are dominated by frequent, intermittent, short term power demands superimposed on a background of aerobic activity.

OBJECTIVE

To gain physiological profiles of highly trained British quadriplegic athletes, and to examine the relation between aerobic and sprint capacity.

METHODS

Eight male quadriplegic athletes performed an arm crank exercise using an ergometer fitted with a Schoberer Rad Messtechnik (SRM) powermeter. The sprint test consisted of three maximum-effort sprints of five seconds duration against a resistance of 2%, 3%, and 4% of body mass. The highest power output obtained was recorded (PPO). Peak oxygen consumption (V(O2peak)), peak heart rate (HR(peak)), and maximal power output (PO(aer)) were determined.

RESULTS

Mean PO(aer) was 67.7 (16.2) W, mean V(O2peak) was 0.96 (0.17) litres/min, and HR(peak) was 134 (19) beats/min for the group. There was high variability among subjects. Peak power over the five second sprint for the group was 220 (62) W. There was a significant correlation between V(O2peak) (litres/min) and PO(aer) (W) (r = 0.74, p<0.05).

CONCLUSIONS

These British quadriplegic athletes have relatively high aerobic fitness when compared with the available literature. Moreover, the anaerobic capacity of these athletes appeared to be relatively high compared with paraplegic participants.

European Pharmacopoeia (EP), USDA and MAFF standards--will they ever be harmonised under the VICH umbrella?

Harmonisation of standards can have benefits for both users and manufacturers of vaccines. It also helps regulatory authorities when products are assessed to have a uniform standard in different regions. The first priority for harmonisation has to be the elimination of duplicate testing for the same purpose, for example tests for safety, immunogenicity and batch potency. A further priority is to harmonise batch-testing requirements first, since duplication of testing affects production batches. Fish vaccines present particularities as far as harmonisation between regions is concerned because of geographical, climatic and other factors. A commitment from regulatory authorities and manufacturers is a precondition for harmonisation. The different parties should commit themselves to harmonisation within a reasonable time and to implementing their decisions promptly. When there is a commitment on the part of all participants to work together in developing common science-based regulatory standards, then the optimal conditions exist. Harmonisation is time-consuming and costly but in the end the benefits can no doubt exceed the investment. Harmonisation also needs a forum since the present terms of reference of regulatory and standardisation bodies do not cover this. The only forum at present is the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Products (VICH), which is a tripartite activity involving the European Union, Japan and the U.S.A. Before deciding to propose inclusion in the VICH programme, a preliminary study should be carried out to assess the benefits expected, the obstacles to harmonisation and the feasibility of achieving a satisfactory result. In the framework of VICH, there have been some successful harmonisation projects for veterinary vaccines: residual formaldehyde determination, and residual moisture determination. A harmonised proposal for mycoplasma testing is now available for public comment. Work on extraneous agents testing for avian and mammalian viral vaccines is well advanced.

Long-term vaginal antibody delivery: delivery systems and biodistribution

Topical delivery systems can provide prolonged delivery of antibodies to the vaginal mucosal surface for long-term protection against infectious diseases. We examined the biodistribution of antibodies during 30 days of vaginal antibody delivery in mice. Different antibody preparations (including monoclonal IgG and IgM, as well as several different (125)I-labeled IgGs) were administered by polymer vaginal rings, which were designed to provide continuous antibody delivery. Antibody concentrations remained high in the vaginal secretions for up to 30 days after disk insertion; radiolabeled antibody was also found, at approximately 100 times lower concentration, in the blood and other tissues. The measured concentrations agreed reasonably well with a simple pharmacokinetic model, which was used to calculate mucosal and systemic concentrations as a function of antibody delivery and elimination rates. Results from the model were consistent with previously reported antibody pharmacokinetic measurements: the half-life for antibody elimination for the vagina was approximately 3 h; the half-life for IgG(1) clearance from the blood was >1 day; and the overall permeability constant for vaginal uptake of IgG was approximately 0.01 to 0.03 h(-1). These results provide important information for the design of controlled antibody delivery devices for vaginal use, and suggest that high-dose, long-term vaginal administration of antibodies may be a reasonable approach for achieving sustained mucosal and systemic antibody levels.

Reference standards for vaccine-producing laboratories

The inherent variability of the biological systems used for production of vaccines is much greater than that encountered in the production of pharmaceuticals. Therefore, producers of vaccines must take particular care to ensure that the different batches of a vaccine are of reasonable consistency and that the immunising activity of each batch is equivalent to that of the vaccine originally shown to be effective in the target species. This struggle for consistency has been the main motive for developing the range of reference standards which serve as fixed reference points during the production and quality control of a vaccine.

Alternatives to animal testing: achievements and recent developments in the European Pharmacopoeia

The European Pharmacopoeia has declared its full support for thorough application of the three Rs in the tests that comprise the official standards. Significant progress has been achieved in the last few years in the fields of pyrogen testing, hormones, blood products and, to a lesser extent, vaccines. Many projects are at present under way. Until recently, the approach was more or less passive, awaiting a consensus on new methods before incorporation into the official standard. However, a more active approach has now been adopted, notably by the organisation of validation exercises both to establish alternative methods and to encourage their wide use. All users of the Pharmacopoeia are concerned by this problem and they should be aware that all proposals and initiatives will be followed up within the means at our disposal.

Turning critics into allies

The siting of psychiatric intensive care units can rouse unreasonable hostility among local communities. Most of the opposition results from fears based on misinformation which can be calmed by a public relations exercise aimed directly at the community concerned.

Visual Observations and Torque Measurements in the Taylor Vortex Regime Between Eccentric Rotating Cylinders

The instability of Taylor vortices in the flow between a stationary outer cylinder and an eccentric rotating inner cylinder has been investigated by visual observations and by torque measurements. It is shown that both a “weak” and “strong” wavy mode of instability can be detected by torque measurements, giving critical Taylor numbers in good agreement with visual observations.