Physiological implications of altitude training for endurance performance at sea level: a review

Acclimatisation to environmental hypoxia initiates a series of metabolic and musculocardio-respiratory adaptations that influence oxygen transport and utilisation, or better still, being born and raised at altitude, is necessary to achieve optimal physical performance at altitude, scientific evidence to support the potentiating effects after return to sea level is at present equivocal. Despite this, elite athletes continue to spend considerable time and resources training at altitude, misled by subjective coaching opinion and the inconclusive findings of a large number of uncontrolled studies. Scientific investigation has focused on the optimisation of the theoretically beneficial aspects of altitude acclimatisation, which include increases in blood haemoglobin concentration, elevated buffering capacity, and improvements in the structural and biochemical properties of skeletal muscle. However, not all aspects of altitude acclimatisation are beneficial; cardiac output and blood flow to skeletal muscles decrease, and preliminary evidence has shown that hypoxia in itself is responsible for a depression of immune function and increased tissue damage mediated by oxidative stress. Future research needs to focus on these less beneficial aspects of altitude training, the implications of which pose a threat to both the fitness and the health of the elite competitor. Paul Bert was the first investigator to show that acclimatisation to a chronically reduced inspiratory partial pressure of oxygen (P1O2) invoked a series of central and peripheral adaptations that served to maintain adequate tissue oxygenation in healthy skeletal muscle, physiological adaptations that have been subsequently implicated in the improvement in exercise performance during altitude acclimatisation. However, it was not until half a century later that scientists suggested that the additive stimulus of environmental hypoxia could potentially compound the normal physiological adaptations to endurance training and accelerate performance improvements after return to sea level. This has stimulated an exponential increase in scientific research, and, since 1984, 22 major reviews have summarised the physiological implications of altitude training for both aerobic and anaerobic performance at altitude and after return to sea level. Of these reviews, only eight have specifically focused on physical performance changes after return to sea level, the most comprehensive of which was recently written by Wolski et al. Few reviews have considered the potentially less favourable physiological responses to moderate altitude exposure, which include decreases in absolute training intensity, decreased plasma volume, depression of haemopoiesis and increased haemolysis, increases in sympathetically mediated glycogen depletion at altitude, and increased respiratory muscle work after return to sea level. In addition, there is a risk of developing more serious medical complications at altitude, which include acute mountain sickness, pulmonary oedema, cardiac arrhythmias, and cerebral hypoxia. The possible implications of changes in immune function at altitude have also been largely ignored, despite accumulating evidence of hypoxia mediated immunosuppression. In general, altitude training has been shown to improve performance at altitude, whereas no unequivocal evidence exists to support the claim that performance at sea level is improved. Table 1 summarises the theoretical advantages and disadvantages of altitude training for sea level performance. This review summarises the physiological rationale for altitude training as a means of enhancing endurance performance after return to sea level. Factors that have been shown to affect the acclimatisation process and the subsequent implications for exercise performance at sea level will also be discussed. Studies were located using five major database searches, which included Medline, Embase, Science Citation Index, Sports Discus, and Sport, in

Recovery from infectious mononucleosis after altitude training in an elite middle distance runner

OBJECTIVES

This investigation was designed to monitor altitude acclimatisation in an elite cohort of distance runners and follow the subsequent recovery from infectious mononucleosis which developed in one of these athletes.

METHODS

Twenty six national standard distance runners performed treadmill tests 24 days before they travelled to an altitude camp (1500 to 2000 m). One of these athletes was diagnosed as suffering from infectious mononucleosis 14 days after return to sea level. A physician prescribed an individualised training programme which was designed to maximise recovery from the condition, which was monitored on days 16 and 147 after altitude training.

RESULTS AND CONCLUSIONS

The data suggest that the athlete was in a state of over-reaching during the altitude sojourn. After return to sea level, the early stages of infectious mononucleosis resulted in a marked impairment in physiological response to endurance exercise, which improved over time. Longitudinal physiological monitoring in conjunction with a carefully prescribed training programme made recovery from this condition possible.

Acute leg ischaemia in Gloucestershire

BACKGROUND

Acute leg ischaemia is both life threatening and limb threatening. This audit was designed to determine the incidence and outcome of acute leg ischaemia in a single county.

METHODS

Using multisource data collection for a 1-year interval in 1994 all patients with acute leg ischaemia were identified prospectively using hospital and general practice records in the county of Gloucestershire, population 540,000.

RESULTS

Seventy-seven patients with 84 events of acute leg ischaemia were identified, giving an incidence of one per 7000 per year rising to one per 6000 per year when bypass graft occlusions were included. All but four patients were treated in hospital. Sixteen of 80 hospital events involved conservative treatment; after 30 days nine patients had died and two required amputation. The remaining five patients had borderline ischaemic rest pain and accepted their symptoms without intervention. Sixty-four of 80 events were managed by either primary surgery and angioplasty (n = 31) or thrombolysis (n = 33). The 30-day outcome in patients treated actively was: limb salvage in 50 (78 per cent), amputation in four (6 per cent) and death in ten (16 per cent).

CONCLUSION

In Gloucestershire almost all cases of acute leg ischaemia are managed by, or discussed with vascular surgeons. A flexible integrated policy of surgery and peripheral thrombolysis has resulted in a limb salvage rate of 78 per cent in patients suitable for active treatment.

Body habitus and coronary heart disease in men. A review with reference to methods of body habitus assessment

Table 1 is a synopsis of the major findings from an extensive literature on the association between human body habitus and coronary heart disease. Whilst some studies have used quite sophisticated laboratory procedures to quantify body fat most have relied upon anthropometric measurements to determine some component of body habitus. Of these, body weight and height are the simplest measurements and are, therefore, well-suited to large-scale prospective studies. Height and weight are highly reproducible measurements, although in the short term, weight can have considerable physiological variation associated with gastric emptying and state of hydration. Less reliable measurements than height and weight are skinfolds and body circumferences, both of which have been used extensively in cross-sectional and prospective analyses. For skinfolds, both the inter and intra-observer variability is affected by the measurement technique, location of the skinfold site, the skinfold caliper used and skinfold compressibility. As measurement error has been shown to be a function of skinfold thickness, accurate and repeatable skinfold measurements are particularly difficult to make in the obese. In these subjects, it is not always possible to locate a specific anatomical bony landmark or to pull a parallel skinfold away from the underlying tissue. Furthermore, in the extremely obese it is sometimes possible for a skinfold to be thicker than the jaws of the currently available commercial calipers. Alternately, body circumferences are obtainable in all subjects and have greater reproducibility than skinfolds. They are, therefore, the preferred method in obese subjects. However, there is considerable work to be done to establish their association with body fatness. The evidence examined in this review suggests that body weight is a poor predictor of coronary heart disease. Some studies have reported no difference in the body weight of coronary heart disease patients compared to subjects free of the disease, others found the body weight of subjects with coronary heart disease to be slightly greater, and one found the body weight of cardiac patients to be less than controls. Height, however, is associated with coronary heart disease in prospective studies with long-term and shorter-term follow-up periods and case-control designs. Fetal, infant and childhood under-nutrition may link shorter adult height and susceptibility to cardiovascular disease. Many researchers have studied the relationship between overweight and coronary heart disease by using a surrogate measurement of body fatness such as relative weight or a weight-for-height index. In general, results produced by these studies suggest weight-for-height indices, particularly the often used body mass index, are not strong predictors of coronary heart disease. Indeed case-control designs have consistently failed to show a relationship between body mass index and coronary heart disease. Inconsistent results from prospective studies, however, are difficult to interpret. To further confuse the situation, the body mass index has been examined in relation to different coronary heart disease end-points and adjusted for different confounding variables. Explaining the inconsistent results on the basis of length of follow-up is also not straightforward. When follow-up periods exceed 20 years, and sample size is small, however, this closer association has not been found, even with a long follow-up period. Whilst some studies have found no association after 15, 13 and 12 years others have reported a relationship after 8.5, 10, 12, 10 and 7 years. The 22 year follow-up evidence from the Framingham Study shows the strongest 'independent' association between body mass index and coronary heart disease. (ABSTRACT TRUNCATED)

Caring for dying children: nurses' experiences

Interviews with 25 nurses in this grounded theory study show that when nurses recognized that a child's death was inevitable, they struggled with both grief distress and moral distress. Their distress occurred within the context of the nurse-patient relationship. Nurses employed a range of strategies to manage their distress. Several conditions facilitated or constrained nurses' strategies, and resulted in far-reaching implications both professionally and personally.

Alteration of tobacco floral organ identity by expression of combinations of Antirrhinum MADS-box genes

Floral organ identity is largely controlled by the spatially restricted expression of several MADS-box genes. In Antirrhinum majus these organ identity genes include DEF, GLO and PLE. Single and double mutant analyses indicated that the type of organ found in a particular whorl is dependent on which combination of these genes is expressed there. This paper reports the ectopic expression of Antirrhinum organ identity genes, alone and in combinations, in transgenic tobacco. Although the phenotypes are broadly in agreement with the genetic predictions, several unexpected features are observed which provide information concerning the action of the organ identity genes. The presumed tobacco homologue of DEF, NTDEF, has been isolated and used to investigate the influence of ectopic expression of the Antirrhinum organ identity genes on the endogenous tobacco genes. Analysis of the spatial and temporal expression patterns of NTDEF and NTGLO reveals that the boundaries are not coincident and that differences exist in the regulatory mechanisms of the two genes concerning both induction and maintenance of gene expression. Evidence is provided which indicates that organ development is sensitive to the relative levels of organ identity gene expression. Expression of the organ identity genes outside the flower or inflorescence produced no effects, suggesting that additional factors are required to mediate their activity. These results demonstrate that heterologous genes can be used to predictably influence floral organ identity but also reveal the existence of unsuspected control mechanisms.

A survey of dental airlines and an examination of tooth-drying techniques

The aims of this study were: 1. To assess the prevalence and severity of water and oil contamination in 20 dental airlines in clinical use, using a commercial test kit, LP Aerotest. 2. To determine the effect, in vitro, of such contamination on the shear bond strengths to etched bovine enamel, of composite resin and a dedicated bonding agent. The enamel was dried using either an oil-and-water-contaminated 3-in-1 syringe, a warm-air tooth-dryer, silica gel-dried air or blotting paper, prior to bonding. A total of 11 (5 mm diameter) composite discs were bonded in each group. The samples were shear tested 72 hours later at a cross-head speed of 50 mm/min. All airlines had > 100 mg/m3 water and traces of oil (< 0.5 mg/m3) were present in 50% of samples. The mean shear bond strengths (MPa) for the 3-in-1 syringe, tooth-dryer, dried air and blotting paper-dried teeth were 14.5 +/- 3.8, 19.0 +/- 2.6, 19.6 +/- 4.2 and 19.7 +/- 1.9 respectively. The differences between the values for the tooth dryer, dry air and blotting paper were not significant (P > 0.01) but a significant difference (P < 0.01) was observed between these and the 3-in-1 syringe.

Multiple interactions amongst floral homeotic MADS box proteins

Most known floral homeotic genes belong to the MADS box family and their products act in combination to specify floral organ identity by an unknown mechanism. We have used a yeast two-hybrid system to investigate the network of interactions between the Antirrhinum organ identity gene products. Selective heterodimerization is observed between MADS box factors. Exclusive interactions are detected between two factors, DEFICIENS (DEF) and GLOBOSA (GLO), previously known to heterodimerize and control development of petals and stamens. In contrast, a third factor, PLENA (PLE), which is required for reproductive organ development, can interact with the products of MADS box genes expressed at early, intermediate and late stages. We also demonstrate that heterodimerization of DEF and GLO requires the K box, a domain not found in non-plant MADS box factors, indicating that the plant MADS box factors may have different criteria for interaction. The association of PLENA and the temporally intermediate MADS box factors suggests that part of their function in mediating between the meristem and organ identity genes is accomplished through direct interaction. These data reveal an unexpectedly complex network of interactions between the factors controlling flower development and have implications for the determination of organ identity.

Comparison of prostatic volume and dimensions by transrectal and transurethral ultrasonography

OBJECTIVE

To compare the volumes and dimensions of the prostate gland as measured by transrectal and transurethral ultrasonography (TRUS and TUUS) and to study the prostatic changes that occur in the presence of an urethral instrument.

PATIENTS AND METHODS

Twenty men (mean age 71 years, range 43-85) with symptoms of prostatic enlargement underwent TRUS and the dimensions and volumes of their prostates were obtained by the dimensional method and by step planimetry. Within 24 h, all the men were examined cystoscopically under sedoanalgesia and underwent TUUS. Their prostatic volumes and dimensions were again measured by the dimensional method and by step planimetry. Step planimetry was carried out using a specially designed indexer firmly attached to the examination couch or operating table. All the static images and planimetry slices were video recorded for later computer enhancement and to study the three-dimensional changes occurring in the prostate. The volumes and dimensions obtained by TRUS and TUUS were compared.

RESULTS

Volumes obtained by transurethral step planimetry were 22% greater than those from transrectal planimetry. Although there was a good correlation (r = 0.984) between transurethral planimetry and the volumes derived using the transurethral dimensions with the prolate ellipsoid formula, the latter produced values 17% and 25% lower by the transurethral and transrectal routes, respectively. These volume estimates varied widely, indicating that the simple addition of a constant to the prolate ellipsoid formula would not correct the volume. Three-dimensional changes of the prostate occurred with TRUS and TUUS: with TUUS, the craniocaudal and anteroposterior diameters were significantly larger (by 7% and 18%, respectively) while the transverse diameter was smaller by 20%.

CONCLUSION

The estimated volumes and dimensions of the prostate differed when measured by TRUS and TUUS and three-dimensional changes in the prostate occurred in the presence of an urethral instrument.

Assessment of need for a children's hospice program

Canuck Place, North America's first free-standing pediatric hospice of its kind, opened in 1995 in British Columbia, Canada. The province-wide program encompasses a broad spectrum of services intended to support community-based care and provide periodic, facility-based respite and palliative care to children with life-threatening, progressive illness and to their families. Loss and grief support is another integral component of the program. The concept of pediatric hospice care is founded on the premise that dying children and their families can benefit from care designed to maximize present quality of life; yet, the creation of such programs must be based on demonstrated need. One vital step in the development of the Canuck Place program was assessing the need for such a program within the province. Data from both traditional quantitative and less traditional qualitative sources were used to document and put forth an argument in support of developing a children's hospice program. The final report addressed several components that are summarized in this article for the purposes of assisting others who may wish to undertake similar projects in their own communities.

Bioavailability and pharmacokinetics of oral topotecan: a new topoisomerase I inhibitor

The results of preclinical and clinical studies indicate enhanced antineoplastic activity of topotecan (SKF 104864-A) when administered as a chronic treatment. We determined the apparent bioavailability and pharmacokinetics of topotecan administered orally to 12 patients with solid tumours in a two-part crossover study. The oral dose of 1.5 mg m-2 was administered as a drinking solution of 200 ml on day 1. The i.v. dose of 1.5 mg m-2 was administered as a 30 min continuous infusion on day 2. The bioavailability was calculated as the ratio of the oral to i.v. area under the curve (AUC) calculated up to the last measured time point. The oral drinking solution was well tolerated. The bioavailability revealed moderate inter-patient variation and was 30% +/- 7.7% (range 21-45%). The time to maximum plasma concentration after oral administration (Tmax) was 0.78 h (median; range 0.33-2.5). Total i.v. plasma clearance of topotecan was 824 +/- 154 ml min-1 (range 535-1068 ml min(-1)). The AUC ratio of topotecan and the lactone ring-opened hydrolysis product (hydroxy acid) was of the same order after oral (0.34-1.13) and i.v. (0.47-0.98) administration. The bioavailability of topotecan after oral administration illustrates significant systemic exposure to the drug which may enable chronic oral treatment.

Canuck place: a hospice for dying children

Parents will never face a more stressful event than the news that their child will die. A child's terminal illness challenges every belief, emotion and dream that a parent has. In addition to the emotional drain, caring for a dying child is physically exhausting. Moreover, the child's illness affects the lives of all brothers, sisters, aunts, uncles and grandparents. The care of these children and their families demands a holistic program of services, including physical and emotional support, as well as tangible ways to relieve parents from the continuous 24-hour care of their child. And after the child has died, the emotional support must continue as families learn to face life without their child.

Association of conventional and exertional coronary heart disease risk factors in 5,000 apparently healthy men

BACKGROUND AND HYPOTHESIS

The aim of this study was to define the prevalence of previously undetected coronary heart disease among asymptomatic males, aged 30-65 years, by means of resting and exercise electrocardiography in conjunction with an analysis of conventional and exertional coronary risk factors.

METHODS

Between January 1985 and December 1989 we examined 5,000 clinically asymptomatic subjects. A detailed case history was obtained for each individual, followed by a complete physical examination, comprehensive blood (including lipid) profile, lung function tests, chest x-ray, a resting 12-lead electrocardiogram (ECG), and a maximal treadmill exercise ECG. Whenever possible, on-line computerized respiratory analysis (Beckman Metabolic Measurement Cart) was carried out during the exercise tests. Conventional and exertional coronary heart disease risk factors were also recorded.

RESULTS

A total of 162 persons (3.2%) showed abnormal S-T segment responses during the exercise or recovery period. Of these, 92 subjects underwent further investigations: coronary angiography (79), 201thallium scanning (13), 201thallium scanning followed by coronary angiography (7). Of the 86 patients who proceeded to coronary angiography, 19 (22%) had either normal coronary artery anatomy or only insignificant disease. Among the 67 (78%) of patients with significant angiographically demonstrable disease, 26 received coronary artery bypass grafting, 7 underwent coronary angioplasty, and the remainder continued on medical management.

CONCLUSIONS

These results are discussed in relation to a variety of conventional and exertional coronary risk factors.

The introduction of mentorship to Project 2000 in Wales

This study focused upon the introduction of mentors in the Common Foundation Programme (CFP) of Project 2000 (UKCC 1986) in Wales. It was commissioned by the Department of Health Research and Development Division on behalf of the Welsh Office Nursing Division. The study was policy oriented and its purpose was to inform future policy decision making through an analysis of the implementation of current policies for pre-registration education. The full title of our research project, 'The practitioner teacher: a study in the introduction of mentors in the pre-registration nurse education programme', implied that a clinically-based nurse practitioner with a designated teaching remit, fulfills a particular role (that of mentor) in the pre-registration nurse education programme. It was the nature, scope and impact of this mentor role during the initial implementation period of the CFP of Project 2000 in Wales to which this study addressed itself.

Evaluation of a fetal monitoring education program

OBJECTIVE

To evaluate the effectiveness of a fetal monitoring education program in increasing nurses' knowledge and clinical skills.

DESIGN

Multicenter randomized control trial.

SETTING

Twelve hospitals in eastern Ontario, Canada.

PARTICIPANTS

One hundred nine volunteer registered nurses randomly assigned, within each hospital, to an experimental (n = 47) or control (n = 62) group. Ninety-six nurses (40 in the experimental group and 56 in the control group) completed the 6-month follow-up (88% retention).

INTERVENTIONS

The experimental group participated in a 1-day fetal monitoring workshop and a review session 6 months later.

MAIN OUTCOME MEASURES

Performance on a 45-item knowledge test and a 25-item skills checklist. The passing score was at least 75% correct on each test.

RESULTS

The percentage of nurses in the experimental group passing both the knowledge and the clinical skills tests after the workshop was significantly higher (p < 0.01) than that of the nurses in the control group: 68.1% versus 6.5%, respectively. A large difference between the groups remained at the 6-month follow-up (experimental, 45%; control, 6.5%). The performance of the nurses in the experimental group improved to an 85% pass rate after they attended the 6-month review session.

CONCLUSION

This comprehensive, research-based program is effective in increasing fetal monitoring knowledge and clinical skills.

Windows on the family

Events in the last few decades have resulted in major changes in the structure of families and in the roles and relationships of family members. As nurses, we deal with the stress-related problems resulting from these changes, and as family roles change, so too do our nursing actions. But exactly what these changes are and how they have affected the family vary according to the perspective of the viewer.

Clarification of advanced nursing practice: characteristics and competencies

Although the term advanced nursing practice has been used extensively to describe the practice of the CNS, it is difficult to find a clear definition of the term. The role has been articulated as a constellation of subroles: clinician, educator, researcher, and consultant. However, describing various subroles does not capture the broader picture of the CNS's contribution to health care delivery. This has lead to discussions among faculty of one university regarding the need to clarify advanced nursing practice as the first step in redesigning the educational preparation for the CNS as an advanced nurse practitioner. In this article, an overview of advanced practice is provided, differences in practice levels are discussed, and characteristics and competencies inherent to advanced nursing practice are delineated. How these characteristics and competencies interact to present a picture of advanced nursing practice is illustrated in a case study.

Microsurgical forehead reconstruction: an aesthetic approach

Satisfactory forehead reconstruction can be accomplished by microsurgical free tissue transfer. Basic principles of forehead resurfacing include: (1) replacement with similar quality soft tissue as a well-defined complete aesthetic unit, (2) establishment of the hairline 5-6 cm above the eyebrows, and (3) use of adjunctive procedures to enhance the aesthetic result. We have found the radial forearm flap and the groin flap to be excellent flaps for achieving this goal.

A physical conditioning program does not alter fibrinogen concentration in young healthy subjects

Twenty five subjects were divided into experimental (N = 13, 7 male and 6 female, age 32.1 +/- 6.4 yr) and control groups (N = 12, 6 male and 6 female, age 33.4 +/- 5.4 yr) in order to examine the effect of a conditioning program on fibrinogen concentration. Before and after conditioning, VO2max was determined in all subjects. The experimental group (E) exercised for 30 min, 3 d.wk-1 for 12 wk at 70% (initial 6 wk) and 80% (latter 6 wk) of maximum heart rate. The control group (C) maintained normal activity pattern. After conditioning, subjects in E, but not in C, increased (P < 0.001) their VO2max. Resting fibrinogen concentrations (RFC) before conditioning were similar between the two groups, and demonstrated no change in the C group (242.9 +/- 40.3 mg.dl-1 vs 247.4 +/- 38.7 mg.dl-1, P > 0.05) after conditioning. Although RFC showed a 6% decrease in the E group post conditioning (249.1 +/- 21.5 mg.dl-1 vs 236.4 +/- 34.6 mg.dl-1), this decrease was not significant (P > 0.05). A significant increase (P < 0.05) in fibrinogen concentrations were observed after maximal exercise in both groups pre and post conditioning; however, this increase disappeared (P > 0.05) when data were corrected for hemoconcentration. These results suggest that after conditioning the 6% decrease in RFC was not statistically significant, but the possibility of Type II error is high.

The L19 ribosomal protein gene (RPL19): gene organization, chromosomal mapping, and novel promoter region

The intron-containing genes encoding rat and human ribosomal protein L19 (RPL19) have been cloned. The DNA sequences of the entire rat RPL19 gene and the 5' end of the human RPL19 gene have been determined. Sequence comparison of corresponding regions of the two genes reveals a striking interspecies homology in the 5' upstream region, outside the transcribed and coding regions. The transcriptional start sites of the two genes have been determined and are identical. Both rat and human RPL19 genes have 5' ends associated with CpG islands. A promoter deletion analysis of the rat RPL19 gene suggests that this promoter may differ from those of all previously characterized ribosomal protein genes in requiring far upstream sequences for efficient gene expression. By fluorescence in situ hybridization analysis, the position of the human RPL19 gene has been sublocalized to 17q11 and may be coamplified with the erbB-2 gene in human breast cancer cells. The similarities and differences between RPL19 and other previously characterized ribosomal protein genes are discussed.