Quantitative analysis of xanthohumol and related prenylflavonoids in hops and beer by liquid chromatography-tandem mass spectrometry

A method for quantitation of six prenylflavonoids (xanthohumol, isoxanthohumol, desmethylxanthohumol, 6- and 8-prenylnaringenins and 6-geranylnaringenin) in hops and beer by HPLC-tandem mass spectrometry has been developed. The method allows direct analysis of beer and crude methanolic extracts of hops. After HPLC separation, prenylflavonoids were detected by positive ion multiple-reaction monitoring using a triple-quadrupole mass spectrometer equipped with a heated nebulizer--atmospheric pressure chemical ionization interface. The accuracy and precision were evaluated by replicate analyses of (spiked) samples. Thirteen commercial beers were analysed with the method. Isoxanthohumol, formed by isomerization of xanthohumol during the brewing process, was the most abundant flavonoid in hopped beers, ranging from 0.04 to 3.44 mg/l.

Transforming growth factor beta isoforms in human optic nerve heads

AIM

To determine if the isoforms of transforming growth factor beta (TGF-beta) are present in fetal, normal adult, and glaucomatous optic nerve heads.

METHODS

To localise cells synthesising TGF-beta, optic nerve heads were stained using antibodies to TGF-beta 1, TGF-beta 2, and TGF-beta 3. To demonstrate synthesis, human optic nerve heads from fetal, glaucomatous, and normal age matched subjects were explanted, cultured overnight, and the culture supernatant was assayed for the presence of TGF-beta 1 and TGF-beta 2 by bioassay. In addition, semiquantitative RT-PCR was performed to determine the gene expression pattern of TGF-beta 2.

RESULTS

Immunohistochemistry of glaucomatous samples revealed the presence of intense staining for TGF-beta 2 primarily in astrocytes, whereas TGF-beta 1 was localised to blood vessels. No TGF-beta 3 immunoreactivity was observed. There was little or no expression of TGF-beta in normal optic nerve heads. Optic nerve heads from glaucomatous eyes released 70-100-fold more TGF-beta 2 than normal age matched optic nerve heads. Fetal optic nerve heads released 90-100-fold more TGF-beta 2 than normal adult optic nerve heads. TGF-beta 1 was undetectable by bioassay in all samples tested. There was no apparent increase in TGF-beta 2 gene expression in glaucomatous and fetal eyes, suggesting post-transcriptional regulatory mechanisms.

CONCLUSIONS

These results demonstrate that TGF-beta 2 is produced in high levels in the fetal and glaucomatous optic nerve heads, perhaps by a mechanism of post-transcriptional regulation. TGF-beta may be important during development of the optic nerve head and, in glaucoma, TGF-beta 2 may be a mediator of astrocyte reactivation and extracellular matrix remodelling in the lamina cribrosa.

The effects of endurance training on muscle fibre types and enzyme activities

Practitioners and scientists have demonstrated great interest in the physiological and biochemical effects of endurance training on the results of the marathon run. It is well documented that athletes with a large proportion of slow twitch and fast twitch aerobic skeletal muscle fibre, high metabolic enzyme activities and concentrations, large mitochondria concentration and, of course, the ability to increase the power output generated for a given rate of oxygen consumption and energy expenditure, are generally highly successful distance runners. Aerobic and endurance training have been shown to bring about significant adaptations to the skeletal muscle and its inclusions as well as to the delivery system. In particular, enzyme activity levels are readily mutable, mitochondrial concentrations increase, and some evidence suggests that the fibre distribution is changed. This article briefly reports on changes in skeletal muscle brought about by endurance training and those changes that appear most effective in yielding success in endurance events.

Evaluation of muscle oxidative potential by 31P-MRS during incremental exercise in old and young humans

The purpose of this study was to compare muscle oxidative capacity between moderately active young and old humans by measuring intracellular threshold (IT) during exercise with 31P-magnetic resonance spectroscopy (31P-MRS). Changes in phosphocreatine, inorganic phosphate, and intracellular pH were measured by 31P-MRS during a progressive unilateral ankle plantar flexion exercise protocol in groups of moderately active old (n = 12, mean age 66.7 years) and young (n = 13, mean age 26.2 years) individuals. From muscle biopsy samples of the lateral gastrocnemius, citrate synthase (CS) activity was determined in six subjects from each group, and fibre type composition was determined in nine old and ten young subjects. The old group had a lower IT for pH, as a percentage of peak work rate (P < 0.05), despite a similar CS activity compared to the young. IT was significantly correlated with CS activity (R = 0.59; P < 0.05), but not with fibre type composition. It was concluded that metabolic responses to exercise are affected by ageing, as indicated by a lower IT in old compared to young individuals.

Suppression of nitric oxide generated by inflammatory macrophages by calcitonin gene-related peptide in aqueous humor

PURPOSE

Ocular immune privilege is mediated in part by the activity of constitutively produced immunosuppressive cytokines and neuropeptides. Aqueous humor was examined for content of calcitonin gene-related peptide (CGRP), and the potential of CGRP to mediate immunosuppressive activity within aqueous humor was determined.

METHODS

The concentration of CGRP in fresh, normal rabbit aqueous humor was assayed by competitive enzyme-linked immunosorbent assay. The ability of CGRP to suppress interferon (IFN)-gamma production by antigen-stimulated, primed lymph node cells was examined by assaying supernatants of stimulated CGRP-treated, primed T-cell cultures for IFN-gamma. The anti-inflammatory activity of aqueous humor and CGRP was assayed by treating IFN-gamma-lipopolysaccharide (LPS)-activated RAW 264.7 cells (macrophages) with aqueous humor, aqueous humor plus anti-CGRP antibody, or CGRP alone. Culture supernatants of the treated macrophages were examined for nitrite by Griess reagent. The production of inducible nitric oxide synthase (NOS2) protein was examined by immunoblotting cell lysates of treated activated macrophages.

RESULTS

The constitutive level of CGRP in fresh, normal rabbit aqueous humor was 5+/-1 x 10(-5) M. At its ocular concentration, CGRP did not inhibit IFN-gamma production by stimulated effector T cells, but it suppressed nitric oxide generation by activated macrophages. Neutralization of CGRP in normal rabbit aqueous humor prevented the aqueous humor from suppressing nitric oxide generation by macrophages. Neither CGRP nor aqueous humor suppressed NOS2 protein synthesis in activated inflammatory macrophages.

CONCLUSIONS

Calcitonin gene-related peptide is a constitutive neuropeptide in aqueous humor. Through CGRP, aqueous humor suppresses nitric oxide production by activated macrophages. This suppression appears to result from inhibiting NOS2 enzymatic activity, rather than from suppressing NOS2 synthesis. The results imply that the ocular microenvironment has diverse immunoregulatory mechanisms that suppress induction, activation, and mediation of immunogenic inflammation.

A small molecular weight factor in aqueous humor acts on C1q to prevent antibody-dependent complement activation

PURPOSE

Aqueous humor inhibits activation of the classic complement pathway; however, the mechanism of this inhibition is unknown. We have examined at the molecular level potential factors responsible for the inhibition, and we have tried to determine where in the complement pathway the inhibition takes place.

METHODS

Fresh rabbit aqueous humor was size fractionated by centrifuge concentrators and by size exclusion column chromatography, and each fraction was assayed for inhibition of the classic complement pathway in a standard CH50 hemolytic assay. Fractions with inhibitory activity were assayed for protein and the presence of ascorbic acid and were subjected to heat treatment. To identify where in the pathway the inhibitor(s) function, the expression of activated complement components bound to the surface of antibody-coated erythrocytes was analyzed by flow cytometry using fluorescein isothiocyanate-labeled antibodies to specific complement components. In addition, hemolytic assays were performed for the function of individual complement components.

RESULTS

The most potent inhibition of the classic pathway was in a fraction of aqueous humor of less than 1.3 kDa. The inhibitory activity in the fraction was unassociated with detectable protein or ascorbic acid, and it remained present after heat treatment. The functional analysis through flow cytometry and hemolytic assays for individual complement components showed that the inhibitor in the less than 1.3-kDa fraction caused a blockade in the complement pathway at the level of C1q.

CONCLUSIONS

The aqueous humor contains a unique potent anticomplementary factor that has a molecular weight less than 1.3 kDa. This heat-stable inhibitory factor inhibits the classic pathway at the level of C1q. These results imply that within the eye the complement pathway is inhibited at the earliest steps of its initiation. Such inhibition would prevent production of complement products that mediate inflammation and chemotaxis of inflammatory cells. Therefore, as part of the adaptation of immune privilege, the ocular microenvironment is protected from inflammation induced by antigen-antibody complexes.

[Maximal aerobic capacity and sports activity in Mexicans from 13 to 56]

The maximum oxygen uptake (VO2máx) of Mexicans living at 2240 m altitude was measured to obtain reference values relating VO2máx with athletic performance, and to evaluate the impact of this measure of cardiorespiratory fitness and sport activity on the ageing process. Clinically healthy male individuals (N = 138), 13 to 56 years of age, were divided into groups by decade and according to sport participation. The VO2máx maximum values for power (Power max), and heart rate (HRmax) were measured while subjects exercised on an electronic cycle ergometer using an open circuit spirometry system. The maximum power index (PImax) was also calculated. The VO2máx indicated that modes of sport activity positively affected aerobic power and "counteracted" age-related decreased in HRmax-, VO2máx-, Powermax-, and PImax.

Differences in health estimates using telephone and door-to-door survey methods--a hypothetical exercise

Telephone interviewing is increasingly being used to obtain data on health issues. Propertly applied telephone interviewing may have considerable cost benefits, but careful thought has to be put into the design of surveys, weighting and analysis of data to avoid major sources of bias. This study is a hypothetical exercise comparing health estimates from a systematic, self-weighting, multistage, clustered, area sample of households using a face-to-face interview method, with hypothetical samples of people obtained from Random Digit Dialling and Electronic White Pages. In a comparison of the population health estimates obtained for a number of health problems in a hypothetical analysis of these samples, the confidence intervals for the estimates overlapped. Since the estimates are not statistically significantly different, it appears that well-planned, appropriately weighted and analysed telephone surveys can be a less expensive way of obtaining health information, however, some caution is expressed in using this method.

The effect of diazepan and exercise training on selected biochemical and histochemical properties of rat skeletal muscle

The effects of chronic diazepam (D) treatment and exercise training on total body mass (TBM), microsomal protein yield (MPY), calcium uptake by fragmented sarcoplasmic reticulum (SR), muscle fibre cross-sectional area, and both PFK and SDH activities were investigated in the tibialis anterior (TA), soleus (Sol), and plantaris (Plt) muscles of 50 male albino Sprague-Dawley rats. Rats were assigned randomly to control (C), sprint-trained (S), or endurance-trained (E) groups. Training was of 12 weeks duration. One-half of each group received daily intraperitoneally D doses of 5 mg kg-1 of TBM. Exercise reduced TBM (p < 0.05); increased the relative BM of the TA (E = 2.02 +/- 0.02, p < 0.01) and Plt (E = 1.15 +/- 0.02, p < 0.01; S = 1.13 +/- 0.03, p < 0.01), as well as the Ca++ uptake of the Sol SR (C = 0.08 +/- 0.02, E = 0.16 +/- 01, p < 0.05). MPY was elevated in S-Sol (C = 1.12 +/- 0.6, S = 1.52 +/- 0.1, p < 0.01). D elevated Sol MPY as well as TA PFK. S-trained animals had lower mean fibre areas than the E-trained (D-treated and untreated) animals. The elevated relative masses of TA and Plt are explained by a decreased TBM with exercise. The increased Ca++ uptake of the Sol indicates that E enhances this function, and the increased MPY probably implies an increased SR. The D could be responsible for the D-elevated Sol MPY as well as the TA PFK. El D did not reduce neuromuscular activity to a level adversely affecting oxidative enzyme activity, but in the case of PFK activity in the TA muscle, such a reduction was evident.

Hormone replacement therapy: prevalence, compliance and the 'healthy women' notion

BACKGROUND

The objective of this study was to assess the current trends of hormone replacement therapy (HRT) use, including rates of use, length of use, continuation rates and characteristics of users and non-users and to examine the hypothesis that 'healthy women' are more likely to be users of HRT.

METHODS

Analysis was carried out of three representative South Australian population studies in 1991, 1993 and 1995 comprising 3019, 3004 and 3016 personal interviews, respectively.

RESULTS

Current use (and ever-use) of HRT in all women aged 50 years and over rose from 13.2% (26.7%) in 1991, to 21.2% (31.9%) in 1993 and 26.0% (40.5%) in 1995. Highest use is now in the 55-59-year age group where, in 1995, current use was 50.9% and ever use was 69.0%. Median compliance rates with HRT rose from 24 months in 1991 to 60 months in 1995 for current users aged 50 years of age or above. The pattern of increasing use of HRT is not consistent across age groups. Analyses of the 1995 data show that, in contrast with increasing rates of current use in women over 55 years, there was no overall change in rates for women below this age. There were no statistically significant differences in health indicators, e.g. blood pressure, smoking, cholesterol levels or body mass index between users and non-users of HRT. However, users reported significantly higher rates of previous osteoporosis and hysterectomy.

CONCLUSIONS

Prevalence rates of HRT use are increasing together with compliance rates and this may reflect increased confidence with HRT therapy. Users of HRT have an increased rate of mammography compared to non-users and this may contribute to earlier detection and, therefore, increased estimates of breast cancer in HRT users. There was no support from the 1995 data for a 'healthy women' hypothesis among HRT users.

Health status of hormone replacement therapy users and non-users as determined by the SF-36 quality-of-life dimension

BACKGROUND

The objective of this study was to compare the health status of women who use and do not use hormone replacement therapy (HRT).

METHOD

The 1994 South Australian Health Omnibus Survey (a population health interview survey) was used to administer the short form-36 health survey questionnaire (SF-36) to users and non-users of HRT. A representative sample of 813 women aged 40 years and older were interviewed. The response rate of the survey was 72.4%. Eight health dimensions of the SF-36 were measured: physical functioning, social functioning, role limitations owing to emotional problems, role limitations owing to physical problems, mental health, vitality, pain and general health.

RESULTS

The mean score for all eight health dimensions was in the bottom 50% of the population for HRT users while non-users were in the upper 50%. Users of HRT had significantly poorer scores for physical limitations, body pain, general health, vitality, social functioning and mental health.

CONCLUSION

Women who use HRT are less healthy than non-users when measured by a generic health status measure.

Public perceptions and self-reported prevalence of osteoporosis in South Australia

The self-reported prevalence of, and attitudes to and perceptions of, osteoporosis in the South Australian community were assessed using data collected as part of the 1995 South Australian Health Omnibus Survey (household interviews)--a clustered, self-weighting, multistage sample of households in metropolitan and country centers. The self-reported prevalence was 4.8 (95% CI: 3.7-5.8) and 1.4% (95% CI: 0.8-2.0) for women (n = 1531) and men (n = 1485) respectively. For individuals with osteoporosis, calcium was the favored treatment (52%), while 33% of women were on hormone replacement therapy. An appropriate definition of osteoporosis was given by 62% of women and 37% of men. The main risk factors were reported as lack of calcium and age. There was a significant association between knowledge of the definition of osteoporosis and identification of correct risk factors. A high perceived risk of osteoporosis was reported in 23% of women and 7% of men. Osteoporosis risk was assessed as higher in those who did not adopt recognized prevention measures. Perception of risk was not related to the individual's own risk factors. Self-reported prevalence of osteoporosis significantly underestimates the likely true prevalence and general awareness and knowledge is much lower for men than women. The importance of individual risk factors for osteoporosis are not understood by the general community.

Aqueous humor induces transforming growth factor-beta (TGF-beta)-producing regulatory T-cells

PURPOSE

The intraocular microenvironment is an immune-privileged site where immunogenic inflammation is suppressed. Suppression of immunogenic inflammation has been associated with immunosuppressive factors found in aqueous humor produced by ocular tissues. To further understand the mechanisms suppressing immunogenic inflammation in the eye, we have examined the production of lymphokines by primed T-cells activated in the presence of aqueous humor.

METHODS

Enriched in vivo primed T-cells were T-cell receptor-stimulated in the presence of fresh aqueous humor. The culture supernatant was assayed for IFN-gamma and IL-4 by sandwich ELISA. TGF-beta production by T-cells stimulated in the presence of aqueous humor was assayed by a TGF-beta bioassay of the culture supernatant and by quantitative RT-PCR for TGF-beta 1 mRNA expression. Aqueous humor-treated T-cells were assayed for their capacity to suppress IFN-gamma production by stimulated, primed T-cells.

RESULTS

Aqueous humor-enhanced proliferation but irreversibly suppressed production of both IFN-gamma and IL-4 by in vitro-activated, in vivo-primed T-cells. Aqueous humor induced in vivo primed T-cells to produce TGF-beta in vitro, and these TGF-beta-producing T-cells suppressed IFN-gamma production by other T-cells activated in co-cultures.

CONCLUSIONS

Aqueous humor alters the functional program of TCR-ligand-activated, primed T-cells, converting the cells to TGF-beta-producing regulatory cells.

Immune deviation in relation to ocular immune privilege

Immune privilege in the eye is a dynamic state in which the immune response to ocular Ags is molded and modified by the eye itself. Immune privilege correlates with systemic alterations in the immune response such that deviant forms of immunity emerge. The eye itself contributes to immune deviation, in part by displaying unique immunoregulatory factors in aqueous humor and expressed on ocular cells. When T cells encounter Ag in the eye, they can become anergic, undergo apoptosis, secrete TGF-beta, and/or release soluble regulatory factors containing the TCR alpha-chain. Ags taken up by indigenous APC escape the eye and reach the spleen where they activate a unique spectrum of Ag-specific T and B cells. The absence of systemic delayed hypersensitivity and complement-fixing Abs in this deviant response probably relates to the fact that inflammation is deleterious to vision and leads to blindness. Immune privilege is the eye's way of protecting its vital function from the ravages of immunopathogenic injury.

Immune deviation in relation to ocular immune privilege

Immune privilege in the eye is a dynamic state in which the immune response to ocular Ags is molded and modified by the eye itself. Immune privilege correlates with systemic alterations in the immune response such that deviant forms of immunity emerge. The eye itself contributes to immune deviation, in part by displaying unique immunoregulatory factors in aqueous humor and expressed on ocular cells. When T cells encounter Ag in the eye, they can become anergic, undergo apoptosis, secrete TGF-beta, and/or release soluble regulatory factors containing the TCR alpha-chain. Ags taken up by indigenous APC escape the eye and reach the spleen where they activate a unique spectrum of Ag-specific T and B cells. The absence of systemic delayed hypersensitivity and complement-fixing Abs in this deviant response probably relates to the fact that inflammation is deleterious to vision and leads to blindness. Immune privilege is the eye's way of protecting its vital function from the ravages of immunopathogenic injury.

Changes in skeletal muscle morphology and biochemistry after cardiac transplantation

Skeletal muscle biopsies (vastus lateralis) were performed in 12 patients (mean age 47 +/- 11 years) before and at 3 and 12 months after cardiac transplantation. Fiber type analysis revealed a predominance of type II fibers before cardiac transplantation (66 +/- 10%); the ratio did not change after transplantation. Fiber cross-sectional area increased by 35% to 39% in all fiber types by 12 months after cardiac transplantation. Fiber cross-sectional area, however, remained below the reported normal values. The number of capillaries surrounding each fiber did not change after cardiac transplantation. Skeletal muscle enzyme activity of phosphofructokinase, citrate synthase, and beta-hydroxyacyl coenzyme A dehydrogenase increased by 26%, 47%, and 63%, respectively, after cardiac transplantation (p < 0.05). Peak oxygen uptake also increased significantly after cardiac transplantation (19.5 +/- 8.1 ml/kg/min at 12 months vs 9.8 +/- 1.4 ml/kg/min before transplant, p < 0.01); however, uptake remained 40% below that of predicted. Thus, significant improvement in skeletal muscle morphology and biochemistry occurs in the first year after cardiac transplantation in association with improved exercise capacity. Recovery, however, may be incomplete, which could explain residual impairment of exercise capacity in these patients.

Immune privilege, T-cell tolerance, and tissue-restricted autoimmunity

The eye is one of several specialized organs/tissues that display immune privilege, i.e. sites that permit foreign tissue grafts to enjoy prolonged (or even indefinite) survival. Immune privilege is an active, rather than a passive, process in which specialized tissues/sites and the immune system collaborate in providing immune protection without the risk of immunopathogenic injury to the tissue itself. Among the mechanisms that have been found to contribute to immune privilege is tolerance of peripheral T cells. Over the past few years, investigators have demonstrated at least four different pathways by which immune privilege can lead to T-cell tolerance: clonal deletion, clonal anergy, immune deviation, and T-cell suppression. In the case of the eye, privilege exists in part because antigens introduced into the eye are captured by distinctive local antigen-presenting cells that migrate via the blood to the spleen. At that site, they generate a stereotypic systemic immune response that is deficient in CD4+ T cells that mediate delayed hypersensitivity and that help B cells to secrete complement-fixing antibodies, yet replete with CD8+ T cells that function as cytotoxic cells and as regulatory cells. This response, termed anterior chamber associated immune deviation (ACAID), is mediated by antigen-specific regulatory T cells that secrete TGFbeta in an autocrine fashion and suppress effector functions of inflammogenic CD4+ T cells. Because intraocular inflammation is deleterious to vision, ACAID and immune privilege are considered to be evolutionary adaptations that enable the eye to benefit from immune protection against pathogens without suffering blindness from immune injury.

Muscle capillarization O2 diffusion distance, and VO2 kinetics in old and young individuals

The relationships between muscle capillarization, estimated O2 diffusion distance from capillary to mitochondria, and O2 uptake (VO2) kinetics were studied in 11 young (mean age, 25.9 yr) and 9 old (mean age, 66.0 yr) adults. VO2 kinetics were determined by calculating the time constants (tau) for the phase 2 VO2 adjustment to and recovery from the average of 12 repeats of a 6-min, moderate-intensity plantar flexion exercise. Muscle capillarization was determined from cross sections of biopsy material taken from lateral gastrocnemius. Young and old groups had similar VO2 kinetics (tau VO2-on = 44 vs. 48 s; tau VO2-off = 33 vs. 44 s, for young and old, respectively), muscle capillarization, and estimated O2 diffusion distances. Muscle capillarization, expressed as capillary density or average number of capillary contacts per fiber/average fiber area, and the estimates of diffusion distance were significantly correlated to VO2-off kinetics in the young (r = -0.68 to -0.83; P < 0.05). We conclude that 1) capillarization and VO2 kinetics during exercise of a muscle group accustomed to everyday activity (e.g., walking) are well maintained in old individuals, and 2) in the young, recovery of VO2 after exercise is faster, with a greater capillary supply over a given muscle fiber area or shorter O2 diffusion distances.

Neuroimmunomodulation in immune privilege: role of neuropeptides in ocular immunosuppression

The microenvironments of the eye and brain are physiologically adapted to protect their delicate structures and functions from damaging immunogenic inflammation (delayed-type hypersensitivity). This adaptation is immune privilege. Aqueous humor, the fluid filling the ocular anterior chamber, suppresses antigen-stimulated primed T cells from mediating inflammation by inhibiting the production of the proinflammatory lymphokine interferon gamma. This suppression is mediated by immunosuppressive cytokines and neuropeptides constitutively produced in the eye and released into aqueous humor. Cerebrospinal fluid has similar immunosuppressive activities, cytokines, and neuropeptides as aqueous humor, indicating that similar mechanisms may mediate immune privilege in the eye and brain. The importance of neuropeptides in mediating immunosuppression indicates that immunosuppressive neuroimmunomodulation has a role in preventing induction of immunogenic inflammation within immune-privileged tissues.

Prevalence and cost of alternative medicine in Australia

BACKGROUND

To determine the prevalence and cost of alternative medicines and alternative practitioner use in an Australian population.

METHODS

We conducted a representative population survey of persons aged 15 or older living in South Australia, which required 3004 personal interviews. We assessed the rates of use and types of alternative medicine and therapists used by this population in 1993, and correlations with other demographic and medical variables.

FINDINGS

The overall use of at least one non-medically prescribed alternative medicine (excluding calcium, iron and prescribed vitamins) was 48.5%. The users were more likely to be perimenopausal females, better educated, have a higher alcohol intake, be of normal weight and more likely to be employed than non-users. 20.3% of respondents had visited at least one alternative practitioner, most commonly chiropractors (15%). The users of alternative practitioners were more likely to be younger, live in the country and be overweight. Women were more likely to consult naturopaths, iridiologists, and reflexologists than men.

INTERPRETATION

Extrapolation of the costs to the Australian population gives a natural expenditure in 1993, for alternative medicines, of $621 million (Australian dollars) and for alternative therapists of $AU309 million per annum. This compares to the $AU360 million of patient contributions for all classes of pharmaceutical drugs purchased in Australia in 1992/93. The public health and economic ramifications of these huge costs are questioned in view of the paucity of sound safety and efficacy data for many of the therapies and products of the alternative medicine industry.

Inhibition of antigen-stimulated effector T cells by human cerebrospinal fluid

The brain is an immune-privilege site. To understand the mechanism of immune privilege in the brain, human cerebrospinal fluid (CSF) was examined for characteristics associated with fluids derived from other immune-privileged tissues. We first assayed for CSF suppression of effector T cell inflammatory activities. Primed T cells were activated with antigen and antigen-presenting cells in the presence of normal human or rabbit CSF, and T cell proliferation and interferon-gamma production were assayed. Human and rabbit CSF enhanced antigen-stimulated lymph node T cell proliferation and human CSF suppressed IFN-gamma production. T cell proliferation was suppressed by a low molecular weight (< 5 kDA) fraction of CSF and by transiently acidified unfractionated CSF. Normal CSF, similar to fluids from other immune-privileged sites, has the capacity to suppress production of proinflammatory lymphokines by antigen-stimulated effector T cells. Normal CSF also contains factors that have the potential to suppress effector T cell proliferation. Human CSF was assayed for factors known to mediate immunosuppression in other immune-privileged sites. Human CSF contained the immunosuppressive cytokine-transforming growth factor-beta (1.7 +/- 0.6 ng/ml), and the immunosuppressive neuropeptides alpha-melanocyte stimulating hormone (60 +/- 11 pg/ml), and vasoactive intestinal peptide (42 +/- 3 ng/ml). Much as fluids from other immune-privileged sites, CSF contains immunosuppressive cytokines that prevent activation of inflammatory-mediating (delayed-typed hypersensitivity) T cells. This suggests that, similar to other immune-privileged sites, cytokines and neuropeptides mediate immunosuppression in the brain.

Basis for aerobic impairment in patients after heart transplantation

BACKGROUND AND METHODS

To evaluate the physiologic basis for the suboptimal peak oxygen uptake observed after heart transplantation, we calculated the functional aerobic impairment ([(peak predicted oxygen uptake-peak observed oxygen uptake)/peak predicted oxygen uptake] x 100) and related it to donor/recipient, operative, and maximal exercise variables. Fifty-seven heart transplant recipients (mean age 50 +/- 10 years, 1 to 9 years after transplantation) underwent maximal upright cycle exercise testing. Concomitant exercise central hemodynamic measurements were obtained in 36 patients (63%).

RESULTS

The mean peak oxygen uptake was 21.7 +/- 6.5 ml/kg/min and functional aerobic impairment was 34% +/- 17%. Functional aerobic impairment correlated positively (p < 0.01) with peak systemic vascular resistance (r = 0.55) and negatively with peak cardiac index (r = -0.62) and peak systemic arteriovenous oxygen difference (r = -0.66). A weak correlation was found between functional aerobic impairment and the duration of cardiac disease (r = 0.35, p < 0.01) but not the origin of heart failure. No correlation was seen between functional aerobic impairment and donor age, total ischemic time, time since transplantation, recipient age, and resting and exercise right and left ventricular filling pressures.

CONCLUSIONS

These results suggest that the decreased exercise capacity observed in heart transplant recipients is in part due to increased peripheral vascular resistance and decreased oxygen extraction possibly due to skeletal muscle atrophy. These factors may be the result of irreversible changes from long-standing heart disease, deconditioning, or the effect of cyclosporine and prednisone.

The effects of high glucose on human endothelial cell growth and gene expression are not mediated by transforming growth factor-beta

BACKGROUND

Because accumulation of extracellular matrix is a prominent characteristic of the microangiopathy that complicates long-term diabetes, a pathogenetic role for transforming growth factor beta (TGF-beta) is being considered. Having observed that glucose levels mimicking diabetic hyperglycemia induce in vitro endothelial cell overexpression of extracellular matrix molecules, decreased replication, and increased levels of TGF-beta mRNA, we have examined whether the effects of high glucose are mediated by autocrine TGF-beta.

EXPERIMENTAL DESIGN

TGF-beta levels were measured by bioassay in the media conditioned by human umbilical vein endothelial cells cultured in the presence of high (30 mM) or normal (5 mM) glucose concentrations. The effect of high glucose was tested on the proliferation of two epithelial cell lines, one (Mv1Lu) exquisitely sensitive to TGF-beta and the other (DR mutants) insensitive to the cytokine. To examine whether high glucose and TGF-beta affect cellular programs in a similar manner, the effects of high glucose and exogenous TGF-beta were compared on proliferation and gene expression of endothelial cells.

RESULTS

Media conditioned by endothelial cells cultured in high or normal glucose contained similar amounts of TGF-beta (4.9 +/- 3.5 and 3.7 +/- 2.5 ng/10(6) cells, respectively (mean +/- SD)), all in the latent form. The replication of parental Mv1Lu cells and their DR mutants was decreased by high glucose to the same extent. Whereas the inhibitory effect of high glucose on endothelial cell replication was reversible, that of TGF-beta was not. Both perturbations induced up-regulation of fibronectin expression, but the effects were additive. Only TGF-beta induced overexpression of Type IV collagenase.

CONCLUSIONS

These combined observations indicate that (a) endothelial cells exposed to high glucose do not secrete TGF-beta in excess of control cells, (b) there are growth-inhibitory effects of high glucose that are independent of TGF-beta, and (c) high glucose and TGF-beta exert their effects through distinct pathways and at different loci.

Evolution of resting lung function in the first year after cardiac transplantation

The aim of our study was to characterize the time course and magnitude of the changes in lung function in the first year after cardiac transplantation. Resting pulmonary function tests (spirometry, lung volumes and transfer factor) were performed in 14 patients prior to and at 1, 3 and 12 months after surgery. Resting central haemodynamics were also measured serially in the first year post-transplantation. Before transplantation, patients had impaired resting lung function with marked decrease in transfer factor (TL,CO). Although resting central haemodynamics improved markedly within the first week after cardiac transplantation, lung function (forced expiratory volume in one second (FEV1)) was significantly improved only at three months post-transplantation. TL,CO, however, decreased further early after cardiac transplantation. By 12 months, FEV1 and forced vital capacity had increased significantly by 31 and 33%, respectively, while total lung capacity increased by 22%. On the other hand, TL,CO did not increase significantly and remained well below normal at 12 months after cardiac transplantation, at a value equal to 68% of predicted. We conclude that the resting abnormalities in lung function of most patients with heart failure are reversible after cardiac transplantation, except for TL,CO which remains below normal values. Recovery of lung function, however, lags behind the improvement in cardiac function.

Evolution of resting lung function in the first year after cardiac transplantation

The aim of our study was to characterize the time course and magnitude of the changes in lung function in the first year after cardiac transplantation. Resting pulmonary function tests (spirometry, lung volumes and transfer factor) were performed in 14 patients prior to and at 1, 3 and 12 months after surgery. Resting central haemodynamics were also measured serially in the first year post-transplantation. Before transplantation, patients had impaired resting lung function with marked decrease in transfer factor (TL,CO). Although resting central haemodynamics improved markedly within the first week after cardiac transplantation, lung function (forced expiratory volume in one second (FEV1)) was significantly improved only at three months post-transplantation. TL,CO, however, decreased further early after cardiac transplantation. By 12 months, FEV1 and forced vital capacity had increased significantly by 31 and 33%, respectively, while total lung capacity increased by 22%. On the other hand, TL,CO did not increase significantly and remained well below normal at 12 months after cardiac transplantation, at a value equal to 68% of predicted. We conclude that the resting abnormalities in lung function of most patients with heart failure are reversible after cardiac transplantation, except for TL,CO which remains below normal values. Recovery of lung function, however, lags behind the improvement in cardiac function.

Changes in the use of hormone replacement therapy in South Australia

OBJECTIVE

To determine changes in the use of hormone replacement therapy (HRT) in South Australia between 1991 and 1993.

DESIGN AND SETTING

Survey of women aged 40 years and over, as part of the 1991 and 1993 South Australian Health Omnibus Surveys (household interviews); 868 were interviewed in 1991 and 790 in 1993.

OUTCOME MEASURES

Rates of HRT use.

RESULTS

In 1993, 19.0% of women aged 40 years and over were taking HRT and 28.5% had ever taken it (currently or in the past). The highest rates were in the 50-54 years age group (46.2% current use and 57.8% ever use). Between 1991 and 1993 there was a 40% increase in the number of women taking HRT and a significant increase (P < 0.01) in the median duration of therapy, from 38 to 54 months. There were also significant increases in rates of use by country women and Australian-born women (P < 0.01). Premarin and Provera remained the most commonly used products in 1993.

CONCLUSION

Australian perimenopausal women are increasingly using HRT. This may reflect recent educational programs on the menopause for both health professionals and the public, and also an increasing number of choices of therapy.

Sleep deprivation: effects on work capacity, self-paced walking, contractile properties and perceived exertion

The primary purpose of this study was to examine the effect of a 48-hour period of sleep deprivation on the performance of selected physical work tasks [30-45% of maximum oxygen consumption (VO2max)]. In addition, this study assessed the effect of continual performance of physical work during sleep deprivation on standardized physiological and psychological test scores. Nineteen male subjects performed six different physical tasks, designed to involve all major muscle groups, during a 48-hour period of sleep deprivation. Fourteen subjects served as sleep-deprivation controls. Performance on all physical work tasks decreased significantly. Neither sleep deprivation (SD) or sleep deprivation in conjunction with continuous physical work (SDW) had any effect on muscle contractile properties, anaerobic power measures or resting blood glucose and lactate concentrations. Only SD subjects demonstrated a decline in cardiorespiratory function. Self-selected walking pace decreased and perceived exertion increased significantly in the SDW group. Positive and negative mood scores were adversely affected in both groups, the total change being greatest in SD subjects. The results indicate that performance of physical work tasks requiring 30-45% VO2max declines significantly over a 48-hour period of sleep deprivation. However, maximal physiological function is not unduly compromised by either the work tasks in conjunction with sleep deprivation or by sleep deprivation alone.

Immunoreactive vasoactive intestinal peptide contributes to the immunosuppressive activity of normal aqueous humor

Suppression of immune-mediated inflammation within the normal anterior chamber (AC) of the eye is in part the result of active suppression of effector T cell activities by immunosuppressive cytokines found in aqueous humor (AqH), the fluid filling the AC. There are immunosuppressive factors found in the low m.w. fraction (< 5 kDa) of AqH, including the neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH). In seeking other factors, we now report that the neuropeptide vasoactive intestinal peptide (VIP) is also present in normal AqH. VIP immunoreactivity was found in normal rabbit eyes at a concentration of 12 +/- 1 nM. At this intraocular concentration, VIP suppressed Ag-stimulated lymph node cell (LNC) proliferation and IFN-gamma production in vitro. Although suppression of LNC proliferation was not neutralized by absorption of VIP from the low m.w. fraction of AqH, removal of VIP did neutralize suppression of IFN-gamma production by this fraction of AqH. Absorption of both VIP and alpha-MSH from this fraction of AqH permitted production of IFN-gamma by Ag-stimulated LNC that was no different than absorbing VIP alone. The low m.w. fraction of AqH absorbed of either alpha-MSH and VIP lost its ability to suppress local adoptive transfer of delayed-type hypersensitivity. The results suggest that VIP is an important immunosuppressive neuropeptide in AqH. Neuropeptides play an important role in ocular immune privilege and creation of an intraocular immunosuppressive microenvironment.

Immunoreactive vasoactive intestinal peptide contributes to the immunosuppressive activity of normal aqueous humor

Suppression of immune-mediated inflammation within the normal anterior chamber (AC) of the eye is in part the result of active suppression of effector T cell activities by immunosuppressive cytokines found in aqueous humor (AqH), the fluid filling the AC. There are immunosuppressive factors found in the low m.w. fraction (&lt; 5 kDa) of AqH, including the neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH). In seeking other factors, we now report that the neuropeptide vasoactive intestinal peptide (VIP) is also present in normal AqH. VIP immunoreactivity was found in normal rabbit eyes at a concentration of 12 +/- 1 nM. At this intraocular concentration, VIP suppressed Ag-stimulated lymph node cell (LNC) proliferation and IFN-gamma production in vitro. Although suppression of LNC proliferation was not neutralized by absorption of VIP from the low m.w. fraction of AqH, removal of VIP did neutralize suppression of IFN-gamma production by this fraction of AqH. Absorption of both VIP and alpha-MSH from this fraction of AqH permitted production of IFN-gamma by Ag-stimulated LNC that was no different than absorbing VIP alone. The low m.w. fraction of AqH absorbed of either alpha-MSH and VIP lost its ability to suppress local adoptive transfer of delayed-type hypersensitivity. The results suggest that VIP is an important immunosuppressive neuropeptide in AqH. Neuropeptides play an important role in ocular immune privilege and creation of an intraocular immunosuppressive microenvironment.

Alpha-melanocyte-stimulating hormone suppresses antigen-stimulated T cell production of gamma-interferon

The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is known to suppress cytokine-mediated inflammation. In addition, we previously found that alpha-MSH suppressed the production of the proinflammatory cytokine interferon (IFN)-gamma by antigen-stimulated primed lymph node T cells. This immunosuppressive activity of alpha-MSH on lymph node T cell cultures is similar to that of interleukin (IL)-4. To further examine the potential 'IL-4 like' activities of alpha-MSH, antigen-stimulated lymph node T cell cultures were treated with alpha-MSH in the presence of neutralizing anti-IL-4 antibodies. The enhanced production of IFN-gamma caused by the presence of anti-IL-4 alone in the T cell cultures was squelched by alpha-MSH. This demonstrated that in these cultures, alpha-MSH regulation of IFN-gamma production operates in a fashion similar to that of endogenous IL-4. Addition of exogenous IL-4 to antigen-stimulated lymph node T cell cultures did not intensify alpha-MSH down-regulation of IFN-gamma production, and the addition of alpha-MSH to IL-4-treated cultures did not further depress IFN-gamma production. These and the previous results suggest that the mechanism of alpha-MSH suppression of IFN-gamma production in the antigen-stimulated T cell cultures is similar to, but independent of, IL-4. When antigen-presenting cells (APCs) were the only cells in the antigen-stimulated T cell cultures treated with alpha-MSH, there was a significant reduction (60-70%) of APC elicitation of IFN-gamma production by untreated primed T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cardiac filling pressures on the release of atrial natriuretic peptide during exercise in heart transplant recipients

OBJECTIVE

To determine the influence of body posture and central hemodynamics on the plasma levels of immunoreactive atrial natriuretic peptide (irANP) during exercise in cardiac transplant patients.

METHODS

Central hemodynamics, mixed expired gas and ventilatory measurements, and venous blood sampling (for irANP determination) were obtained in cardiac transplant patients at rest and during supine (n = 12) or upright (n = 12) graded cycle exercise. Cardiopulmonary and irANP responses to exercise were compared between the upright and supine postures.

RESULTS

At rest (supine), irANP concentrations were similar in both groups (172 +/- 87 pg/mL supine and 182 +/- 72 pg/mL upright) and did not correlate with resting supine central hemodynamics. During exercise, central filling pressures increased in both groups but patients exercising in the supine position had a greater increase. Peak exercise right atrial pressure was 12 +/- 4 mmHg supine versus 7 +/- 5 mmHg upright (P < 0.005). Peak exercise pulmonary capillary wedge pressure was 22 +/- 6 mmHg supine versus 14 +/- 5 mmHg upright (P < 0.005). At peak exercise, irANP levels were greater in the supine than upright position (419 +/- 166 pg/mL supine versus 277 +/- 40 pg/mL upright, P < 0.05). The change in irANP from rest to peak exercise correlated (P < 0.05) with changes in pulmonary capillary wedge pressure (r = 0.67), systolic pulmonary artery pressure (r = 0.78) and right atrial pressure (r = 0.53). There was, however, no correlation between change in irANP and peak oxygen consumption, change in heart rate or change in mean arterial blood pressure.

CONCLUSIONS

In cardiac transplant recipients, exercise is a stimulus for ANP secretion, and augmentation in plasma irANP levels during exercise is modulated by changes in central hemodynamics.

Acute and chronic response of skeletal muscle to resistance exercise

Skeletal muscle tissue is sensitive to the acute and chronic stresses associated with resistance training. These responses are influenced by the structure of resistance activity (i.e. frequency, load and recovery) as well as the training history of the individuals involved. There are histochemical and biochemical data which suggest that resistance training alters the expression of myosin heavy chains (MHCs). Specifically, chronic exposure to bodybuilding and power lifting type activity produces shifts towards the MHC I and IIb isoforms, respectively. However, it is not yet clear which training parameters trigger these differential expressions of MHC isoforms. Interestingly, many programmes undertaken by athletes appear to cause a shift towards the MHC I isoform. Increments in the cross-sectional area of muscle after resistance training can be primarily attributed to fibre hypertrophy. However, there may be an upper limit to this hypertrophy. Furthermore, significant fibre hypertrophy appears to follow the sequence of fast twitch fibre hypertrophy preceding slow twitch fibre hypertrophy. Whilst some indirect measures of fibre number in living humans suggest that there is no interindividual variation, postmortem evidence suggests that there is. There are also animal data arising from investigations using resistance training protocols which suggest that chronic exercise can increase fibre number. Furthermore, satellite cell activity has been linked to myotube formation in the human. However, other animal models (i.e. compensatory hypertrophy) do not support the notion of fibre hyperplasia. Even if hyperplasia does occur, its effect on the cross-sectional area of muscle appears to be small. Phosphagen and glycogen metabolism, whilst important during resistance activity appear not to normally limit the performance of resistance activity. Phosphagen and related enzyme adaptations are affected by the type, structure and duration of resistance training. Whilst endogenous glycogen reserves may be increased with prolonged training, typical isotonic training for less than 6 months does not seem to increase glycolytic enzyme activity. Lipid metabolism may be of some significance in bodybuilding type activity. Thus, not surprisingly, oxidative enzyme adaptations appear to be affected by the structure and perhaps the modality of resistance training. The dilution of mitochondrial volume and endogenous lipid densities appears mainly because of fibre hypertrophy.

Morphometric assessment of the central retinal artery and vein in the optic nerve head

The exact anatomy of the central retinal vein as it exits the eye is unknown. In this study serial sections of the central retinal vein and artery in the anterior optic nerve from six globes (five from cornea donors and one exenteration specimen) were examined by image analysis and three-dimensional reconstruction to determine their luminal characteristics. The retinal artery was found to have a uniform perimetric length and cross-sectional area. The vein, however, had a reduction in these measurements at the level of the lamina cribrosa, signifying a constriction of the vessel at this site. In addition, the cross section of the vein usually formed a "D" or crescentic shape adjacent to the circular artery. We propose that the constriction of the vein acts as a "throttle" mechanism on venous blood flow. Thus, a relatively high venous blood pressure is maintained within the high-pressure intraocular environment, thereby maintaining the patency of the retinal venules and capillaries.

Effect of water temperature on exercise-induced maternal hyperthermia on fetal development in rats

The objective of this study was to determine if water temperature influenced exercise-induced hyperthermia in swim-trained pregnant rats and the resulting fetal development. Pregnant Sprague-Dawley rats with 6 weeks pre-pregnancy training were exercised daily from day 1 to day 18 of gestation in water that was 34.6 +/- 0.4 degrees C (Cool Water Swimmers--CWS) or 37.6 +/- 0.1 degrees C (Warm Water Swimmers--WWS), for one hour/day. During this time period another group of pregnant rats was immersed to the neck in warm water (37.6 +/- 0.2 degrees C) (Warm Water Controls--WWC). On day 19 of gestation all animals were sacrificed and fetal development assessed. Maternal exercise in warm water elevated maternal body core temperature by 2.3 +/- 0.1 degrees C above resting values, with an increase in fetal abnormalities compared to the same exercise intensity in cool water. Fifty-eight percent of the abnormal fetuses and 60% of the resorption sites were found in the WWS group. Of the abnormalities determined, 65% were from the WWS group and 45% of these fetuses showed micrencephaly. Results suggest cool water may regulate maternal body temperature during swimming exercise and that swimming in warm water should be avoided during gestation because of potential teratogenic effects.

Synthesis and antifungal selectivity of new derivatives of amphotericin B modified at the C-13 position

The syntheses of the first amphotericin B derivatives to be modified solely at the C-13 hemiketal position are described. Selective functionalisation at this position is facilitated by use of the allyl ester as a C-16 carboxylate protecting group on the amphotericin B nucleus. In in vitro tests all compounds showed markedly reduced haemolytic activity against mammalian erythrocytes while two of the novel 13-alkoxy derivatives retained good antifungal activity.

Effects of motor unit losses on strength in older men and women

The influence of age-associated motor unit loss on contractile strength was investigated in a representative sample of healthy, active young and older men and women. In 24 younger subjects (22-38 yr) and 20 older subjects (60-81 yr) spike-triggered averaging was employed to extract a sample of surface-recorded single motor unit action potentials (S-MUAPs) from the biceps brachii and brachialis muscles. The amplitude of the maximum compound muscle action potential of the biceps brachii and brachialis muscles was divided by the mean S-MUAP amplitude to estimate the numbers of motor units present. The maximum isometric twitch contraction (MTC) and maximum voluntary contraction (MVC) of the elbow flexors were also recorded in 18 of the younger subjects and in all older subjects. The estimated numbers of motor units were significantly reduced (47%, P < 0.001) in older subjects with a mean value of 189 +/- 77 compared with a mean of 357 +/- 97 in younger subjects. The sizes of the S-MUAPs, however, were significantly larger in older subjects (23%, P < 0.01). Significant but less marked age-associated reductions in the MTC (33%, P < 0.05) and MVC (33%, P < 0.001) were also found and were similar for both men and women. These results suggest that motor unit losses, even in healthy active individuals, are a primary factor in the age-associated reductions in contractile strength.

Effects of motor unit losses on strength in older men and women

The influence of age-associated motor unit loss on contractile strength was investigated in a representative sample of healthy, active young and older men and women. In 24 younger subjects (22-38 yr) and 20 older subjects (60-81 yr) spike-triggered averaging was employed to extract a sample of surface-recorded single motor unit action potentials (S-MUAPs) from the biceps brachii and brachialis muscles. The amplitude of the maximum compound muscle action potential of the biceps brachii and brachialis muscles was divided by the mean S-MUAP amplitude to estimate the numbers of motor units present. The maximum isometric twitch contraction (MTC) and maximum voluntary contraction (MVC) of the elbow flexors were also recorded in 18 of the younger subjects and in all older subjects. The estimated numbers of motor units were significantly reduced (47%, P < 0.001) in older subjects with a mean value of 189 +/- 77 compared with a mean of 357 +/- 97 in younger subjects. The sizes of the S-MUAPs, however, were significantly larger in older subjects (23%, P < 0.01). Significant but less marked age-associated reductions in the MTC (33%, P < 0.05) and MVC (33%, P < 0.001) were also found and were similar for both men and women. These results suggest that motor unit losses, even in healthy active individuals, are a primary factor in the age-associated reductions in contractile strength.

Identification of alpha-melanocyte stimulating hormone as a potential immunosuppressive factor in aqueous humor

The aqueous humor of the eye contains factors that regulate immunological responses within the immunosuppressive ocular microenvironment. Besides TGF-beta, the proteins in the low molecular weight (< 3500 Da) fraction of normal aqueous humor are also immunosuppressive. The low molecular weight fraction of aqueous humor inhibits IFN-gamma production and proliferation of antigen-stimulated lymph node cells. Neuropeptides are one possible family of low molecular weight factors in aqueous humor. Through the utilization of an antigen capturing enzyme-assay, the immunosuppressive neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) was detected in normal aqueous humor of humans, rabbits, and mice. The mean concentration of alpha-MSH in normal aqueous humor of humans was 20 +/- 3 pM, of rabbits 11 +/- 1 pM, of BALB/c mice 16 +/- 3 pM, and of C57BL/6 mice 14 +/- 3 pM. These physiological concentrations of alpha-MSH inhibited the production of IFN-gamma by antigen-stimulated lymph node cells. In contrast to the low molecular weight fraction, alpha-MSH did not inhibit proliferation. There was a 26% recovery of IFN-gamma production when alpha-MSH was absorbed from the low molecular weight fraction. The results demonstrate neuropeptides to be constitutive components of normal aqueous humor and that factors with the capability of differential regulation of effector T-cell activity may be present within the immunosuppressive ocular microenvironment.

Ageing: a normal degenerative process--with or without regular exercise

The purpose of this symposium was to review the physical, metabolic, psychological, and physiological manifestations of the ageing process. A great deal of research has been carried out in the past 10 years with elderly subjects. Investigations are currently expanding to use invasive methodologies previously applied to healthy young subjects. A most comprehensive account of exercise and the elderly is given by Stamford (1988), with insight into the physical capabilities of some 10% of the Canadian population. Ageing affects the total body and its metabolism including hemodynamics, enzyme activities, strength, muscle contraction, and incidence of disease. Equally important, ageing affects the Canadian economy, geographic demographics of retirees, and ethical consideration of the prolongation of life without quality. The symposium papers analyze the ageing process in humans and animal species from biochemical (Kaldor), physiological (Paterson), mechanical (Vandervoort), and psychological (Brown) viewpoints.

Skeletal muscle metabolism in the offspring of trained rats

To determine the effects of maternal exercise training during pregnancy on skeletal muscle metabolism of the progeny, eleven female Sprague-Dawley rats were divided into an exercise and a control group. The maternal training group (6) ran on a rodent treadmill for 4 weeks prior to pregnancy and daily throughout gestation (21 days) at 26.8 m/min, 1 hour/day, 5 days per week. The measurements were taken 28 days postpartum. No differences were noted between the sedentary and trained maternal animals for succinic dehydrogenase (SDH), phosphofructokinase (PFK), and myosin ATPase activities of the soleus, plantaris and gastrocnemius muscles. Maternal gastrocnemius SDH and soleus PFK levels were significantly (p less than 0.05) lower than levels found in the offspring. The liver glycogen of trained maternal animals was significantly higher than that found in all other groups. As well it was shown that maternal exercise had no effect on any of the aforementioned physiological parameters measured in the pups. The results indicate that exercise training during pregnancy does not modify the skeletal muscle metabolism of the offspring as observed 28 days after birth.

Magnetic resonance imaging and 31P spectroscopy of an interictal cortical spike focus in the rat

Magnetic resonance imaging (MRI) has proven to be an effective noninvasive technique for identifying lesions in patients with temporal lobe epilepsy. It has also been suggested that MRI may be sensitive to transient functional or metabolic changes in brain tissue. Increased brain electrical activity as monitored by electroencephalography causes changes in cerebral metabolism that may be responsible for focal or regional alterations in signal in the MRI of some patients. To test this hypotheses, experimental interictal cortical foci were produced in rats by topical application of penicillin to one hemisphere of the brain. In vivo MRI and phosphorous-31 (31P) spectroscopy of the focal and contralateral hemifield were performed in a 30-cm bore 1.89-T Bruker MSL system. 31P spectroscopy revealed no quantifiable differences in pH or in phosphocreatinine and ATP levels between the focal area and the contralateral hemisphere or between experimental and saline-treated control animals. There were also no differences in proton MRI. Similar areas of prolonged T2 were found near the cortex and in the deeper parenchyma in 55% of the experimental animals and 50% of the controls. These results suggest that the electrical activity from an interictal cortical spike focus is not severe enough to perturb cerebral metabolism sufficiently to be detectable by 31P spectroscopy or proton imaging techniques.

Effect of alpha-2-macroglobulin on cytokine-mediated human C-reactive protein production

Alpha-2-macroglobulin (alpha 2-M), a serum protease inhibitor that also binds cytokines, neutralized the inhibitory effect exerted by transforming growth factor-beta (TGF-beta) on IL-6-induced C-reactive protein (CRP) production by the human hepatoma cell line PLC/PRF/5. alpha 2-M was found to bind noncovalently with TGF-beta to form a complex that, upon acidification, released TGF-beta inhibitory activity as detected by IL-6-induced CRP production. Although alpha 2-M also binds IL-6, it did not alter IL-6-induced CRP production by the hepatoma cells. The interaction between alpha 2-M and TGF-beta may influence the production of acute-phase proteins by liver hepatocytes.

Acute and chronic responses of skeletal muscle to endurance and sprint exercise. A review

Skeletal muscle adapts to the stress of endurance and sprint exercise and training. There are 2 main types of skeletal muscle fibre--slow twitch (ST) and fast twitch (FTa, FTb, FTc). Exercise may produce transitions between FT and ST fibres. Sprint training has decreased the proportion of ST fibres and significantly increased the proportion of FTa fibres, while endurance training may convert FTb to FTa fibres, and increase the proportion of ST fibres (i.e. FTb----FTa----FTc----ST). However, the high proportion of ST fibres documented for elite endurance athletes may be simply the result of natural selection. ST fibres function predominantly during submaximal exercise, whereas FT fibres are recruited as exercise intensity approaches VO2max and/or glycogen stores are depleted. Long distance runners have greater ST and FT fibre areas than untrained controls. However, doubt remains as to whether the ST or FT fibre area is greatest in endurance athletes. Increases in FT fibre area seem to occur during the first 2 months of training whereas ST fibre areas appear to increase after 2 to 6 months of training. Sprint training leads to the preferential use of FT fibres and male, but not female sprinters have larger FT fibres than untrained controls. Mitochondrial proteins and oxidative enzymes, as opposed to VO2max, are important determinants of the duration of endurance exercise. Endurance training increases intramuscular glycogen stores in both FT and ST fibres and produces a 'glycogen-sparing' effect which is characterised by an increased free fatty acid (FFA) metabolism. The activity of glycogen synthase is also increased by endurance training. Sprint training increases glycogen concentrations similarly in all fibre types, reduces the rate of glycogen utilisation at submaximal workloads and allows supramaximal workloads to be maintained for longer periods of time. During endurance exercise the pattern of glycogen depletion varies between muscle fibre types and between muscle groups. Glycogen stores in ST fibres are utilised initially, followed by stores in FTa then FTb fibres. Sprint activities are associated with a much greater rate of glycogen depletion. However, it is unlikely that glycogen depletion causes fatigue during sprinting. Sprint work is associated with a preferential depletion of glycogen from FTb then FTa and ST fibres. Endurance training appears to increase triglyceride stores adjacent to mitochondria and ST fibres have greater triglyceride stores than FT fibres. Endurance exercise is associated with a preferential use of triglycerides from ST fibres and endogenous triglycerides may account for over 50% of the total lipid oxidised during exercise.(ABSTRACT TRUNCATED AT 400 WORDS)

Regulation of cytokine-induced human C-reactive protein production by transforming growth factor-beta

Transforming growth factor-beta (TGF-beta) modified production of the major human acute phase reactant, C-reactive protein (CRP), induced by the inflammatory cytokines, IL-1 beta or IL-6. CRP mRNA accumulation in the hepatoma PLC/PRF/5 cell line was slightly more rapid, but of smaller magnitude in response to IL-1 beta (fourfold increase) than to IL-6 (10-fold increase); however, the amount of CRP protein accumulating in the culture medium was similar for both cytokines. TGF-beta at concentrations greater than or equal to 0.1 pg/ml inhibited the induced IL-1 or IL-6 CRP production; whereas concentrations less than 0.1 pg/ml slightly enhanced CRP synthesis. Addition of TGF-beta to the cultures up to 16 h after the PLC/PRF/5 cells were already exposed to IL-1 or IL-6 resulted in the cessation of CRP production. CRP mRNA accumulated in hepatoma cells treated with both TGF-beta and IL-6, although CRP protein synthesis was inhibited. A similar pattern of inhibition of CRP production by TGF-beta occurred when Hep 3B.2 cells were treated with a mixture of IL-1 and IL-6. Enhanced production of CRP was observed only when TGF-beta was added to the cells before the cytokine. This enhanced CRP response was sensitive to cycloheximide. TGF-beta added along with IL-6 inhibited the metabolic labeling of CRP with [35S]methionine; however, enhanced incorporation of [35S]methionine into CRP was observed when the cells were exposed to TGF-beta before IL-6 addition. Therefore, TGF-beta is potentially a potent regulator of CRP synthesis by hepatocytes at the post-transcriptional level.

Regulation of cytokine-induced human C-reactive protein production by transforming growth factor-beta

Transforming growth factor-beta (TGF-beta) modified production of the major human acute phase reactant, C-reactive protein (CRP), induced by the inflammatory cytokines, IL-1 beta or IL-6. CRP mRNA accumulation in the hepatoma PLC/PRF/5 cell line was slightly more rapid, but of smaller magnitude in response to IL-1 beta (fourfold increase) than to IL-6 (10-fold increase); however, the amount of CRP protein accumulating in the culture medium was similar for both cytokines. TGF-beta at concentrations greater than or equal to 0.1 pg/ml inhibited the induced IL-1 or IL-6 CRP production; whereas concentrations less than 0.1 pg/ml slightly enhanced CRP synthesis. Addition of TGF-beta to the cultures up to 16 h after the PLC/PRF/5 cells were already exposed to IL-1 or IL-6 resulted in the cessation of CRP production. CRP mRNA accumulated in hepatoma cells treated with both TGF-beta and IL-6, although CRP protein synthesis was inhibited. A similar pattern of inhibition of CRP production by TGF-beta occurred when Hep 3B.2 cells were treated with a mixture of IL-1 and IL-6. Enhanced production of CRP was observed only when TGF-beta was added to the cells before the cytokine. This enhanced CRP response was sensitive to cycloheximide. TGF-beta added along with IL-6 inhibited the metabolic labeling of CRP with [35S]methionine; however, enhanced incorporation of [35S]methionine into CRP was observed when the cells were exposed to TGF-beta before IL-6 addition. Therefore, TGF-beta is potentially a potent regulator of CRP synthesis by hepatocytes at the post-transcriptional level.

Effect of dietary manipulation on a high intensity performance test

The effects of dietary manipulation (low- or high-carbohydrate) on performance of a short-duration exercise were studied with endurance- and intermittent-trained athletes. Eight subjects performed a depletion drill of 10 one minute workbouts at 7 W/kg and 85 rpm on a cycle ergometer. The subjects followed a dietary regimen of three days on a low-carbohydrate diet followed by three days on a high-carbohydrate diet. Muscle biopsy samples were taken immediately prior to and immediately after the testing sessions. Dietary manipulation did not affect resting muscle glycogen levels. However, subjects accustomed to continuous training regimens used less glycogen, produced less muscle lactate and exercised longer than subjects accustomed to intermittent training programs. These biochemical changes appeared to be related to the fibre type distribution and the training background of the athletes.

Effects of beta 1- vs. beta 1 + beta 2-blockade on exercise endurance and muscle metabolism in humans

The effects of beta-blockade on muscle utilization of glycogen and triglycerides, as well as potassium metabolism, were studied in eight healthy male subjects performing long-duration exercise to exhaustion. Subjects were studied after treatment with either placebo (PLAC), beta 1-selective (atenolol, 100 mg/day, AT), or nonselective beta-blockade (nadolol, 80 mg/day, NAD) each for 1 wk according to a randomized, double-blind, cross-over design. NAD and AT caused identical decreases in exercise heart rates, but endurance (71 +/- 8 min with PLAC) decreased significantly more with NAD (-33 +/- 4%) than with AT (-14 +/- 6%). Muscle glycogen breakdown, taking exercise time into account, was unaffected by treatment. In contrast, muscle triglyceride utilization was completely blocked by NAD whereas it was unchanged with AT as compared to PLAC. Adipose tissue lipolysis was inhibited to a similar extent by the two beta-blockers. Serum potassium increased to higher levels at exhaustion and muscle potassium decreased to lower levels with NAD than with AT or PLAC. These results suggest that decreased utilization of muscle triglycerides combined with lack of an enhanced glycogenolysis to compensate as well as alterations in potassium metabolism contribute to the decreased exercise capacity with nonselective beta-blockade compared with beta 1-selective blockade.

Fatigue and recovery contractile properties of young and elderly men

The 24 h recovery pattern of contractile properties of the triceps surae muscle, following a period of muscle fatigue, was compared in physically active young (25 years, n = 10) and elderly (66 years, n = 7) men. The fatigue test protocol consisted of 10 min of intermittent submaximal 20 Hz tetani. The maximal twitch (Pt) and tetanic force at 3 frequencies (10, 20 and 50 Hz) were determined at baseline and at 15 min, 1, 4 and 24 h after fatiguing the muscle. Maximal voluntary contraction (MVC) and vertical jump (MVJ) were also assessed. The loss of force during the fatigue test was not significantly different between the young (18 +/- 13%) and elderly (22 +/- 15%). Both groups showed similar and significant reductions of Pt (15%), tetanic force (10 to 35%) and rate of force development (dp/dt) (20%) 15 min and 1 h into recovery. The loss of force was greater at the lower stimulation frequencies of 10 and 20 Hz. Time-to-peak tension was unchanged from baseline during recovery in either group. The average rate of relaxation of twitch force (-dPt/dt) was decreased (p less than 0.05) and half-relaxation time significantly increased at 15 min and 1 h in the elderly but not the young. The findings indicate that after fatiguing contractions, elderly muscle demonstrates a slower return to resting levels of the rate and time course of twitch relaxation compared to the young.

Lipoprotein lipase activity in skeletal muscle and adipose tissue of marathon runners after simple and complex carbohydrate-rich diets

A comparison of the influence of simple and complex carbohydrate (CHO) consumption on adipose tissue- and skeletal muscle-lipoprotein lipase activity (AT-LPLA, SM-LPLA) was examined. Twenty male marathon runners were divided into two equal dietary groups: simple-CHO and complex-CHO. Half of the subjects in each group consumed either a low-CHO (15% energy [E] intake), or a mixed diet (50% CHO) for 3 days. Immediately following this dietary period, the subjects consumed a CHO-rich diet (70% E intake) predominant in simple-CHO or in complex-CHO for an additional 3 days. Thereafter, all subjects returned to a normal mixed diet. Skeletal muscle biopsies, adipose tissue aspirations, and venous blood samples were obtained prior to dietary manipulation (PRE), upon completion of the 6 day diet (POST I), and 2 weeks after returning to a normal diet (POST II). The samples were analysed for AT-LPLA, SM-LPLA, serum insulin, and free fatty acids (FFA), and blood glucose, and lactate. SM-LPLA fell 71% from PRE values of 0.39 +/- 0.30 mu mol.g-1.h-1 to POST I values of 0.11 +/- 0.09 mu mol.g-1.h-1 (means +/- SD) (p less than 0.05), after a complex-CHO diet. However, the simple-CHO diet did not alter SM-LPLA. AT-LPLA similarly decreased (p less than 0.05) after the complex-CHO diet, and no significant decrease was noted after the simple-CHO diet.(ABSTRACT TRUNCATED AT 250 WORDS)