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Biomedical subjects

D M Bailey

Publications and source records attributed to D M Bailey.

At least 19 recordsLinked to original sources
PubMed2006

Long-term change in benthopelagic fish abundance in the abyssal northeast Pacific Ocean.

Food web structure, particularly the relative importance of bottom-up and top-down control of animal abundances, is poorly known for the Earth's largest habitats: the abyssal plains. A unique 15-yr time series of climate, productivity, particulate flux, and abundance of primary consumers (primarily echinoderms) and secondary consumers (fish) was examined to elucidate the response of trophic levels to temporal variation in one another. Towed camera sled deployments in the abyssal northeast Pacific (4100 m water depth) showed that annual mean numbers of the dominant fish genus (Coryphaenoides spp.) more than doubled over the period 1989-2004. Coryphaenoides spp. abundance was significantly correlated with total abundance of mobile epibenthic megafauna (echinoderms), with changes in fish abundance lagging behind changes in the echinoderms. Direct correlations between surface climate and fish abundances, and particulate organic carbon (POC) flux and fish abundances, were insignificant, which may be related to the varied response of the potential prey taxa to climate and POC flux. This study provides a rare opportunity to study the long-term dynamics of an unexploited marine fish population and suggests a dominant role for bottom-up control in this system.

Animals↗
PubMed2005

Trends in body size across an environmental gradient: a differential response in scavenging and non-scavenging demersal deep-sea fish.

Body size trends across environmental gradients are widely reported but poorly understood. Here, we investigate contrasting relationships between size (body mass) and depth in the scavenging and predatory demersal ichthyofauna (800-4800 m) of the North-east Atlantic. The mean size of scavenging fish, identified as those regularly attracted to baited cameras, increased significantly with depth, while in non-scavengers there was a significant decline in size. The increase in scavenger size is a consequence of both intra and inter-specific effects. The observation of opposing relationships, in different functional groups, across the same environmental gradient indicates ecological rather than physiological causes. Simple energetic models indicate that the dissimilarity can be explained by different patterns of food distribution. While food availability declines with depth for both groups, the food is likely to be in large, randomly distributed packages for scavengers and as smaller but more evenly distributed items for predators. Larger size in scavengers permits higher swimming speeds, greater endurance as a consequence of larger energy reserves and lower mass specific metabolic rate, factors that are critical to survival on sporadic food items.

Animals↗
PubMed2004

Adenomatous colonic polyps are rare in ulcerative colitis.

BACKGROUND: Uncertainty exists as to whether dysplastic polyps in ulcerative colitis should always be managed as dysplasia-associated lesions/masses requiring colectomy, or whether some can be managed by polypectomy. The prevalence of non-inflammatory polyps in ulcerative colitis is unknown. AIM: To compare dysplastic polyp occurrence in patients with ulcerative colitis and in patients without inflammatory bowel disease. METHODS: The clinical, endoscopic and histological records of 150 ulcerative colitis patients (median disease duration, 10 years; 57% with pancolitis) undergoing colonoscopy were scrutinized for any polyp history. Two hundred and five patients undergoing colonoscopy for altered bowel habit, but without features suggestive of polyp presence, were used as a control group. Immunohistochemical staining of flat and polypoid mucosa for p16, beta-catenin, p53 and cyclo-oxygenase-2 was compared in the two groups. RESULTS: Only six (4%) ulcerative colitis patients had ever had dysplastic polyps. Two had single adenomatous polyps proximal to the colitis segment. Of the four patients with dysplastic polyps within colitic mucosa, two were treated endoscopically, but in two the lesions were considered to be dysplasia-associated lesions/masses and colectomy was advised. In contrast, 24 controls had at least one adenomatous polyp (chi(2) = 6.7, P < 0.01). Ten (6.7%) ulcerative colitis patients and 24 (12%) control patients had metaplastic polyps (N.S.). Immunohistochemical staining was not discriminatory. CONCLUSION: Despite the increased cancer risk in long-standing ulcerative colitis, adenomatous polyps arise less frequently in ulcerative colitis patients than in patients without ulcerative colitis.

Adenomatous Polyposis Coli↗
PubMed2004

Prolonged vitamin C supplementation and recovery from eccentric exercise.

We have previously shown that vitamin C supplementation affects recovery from an unaccustomed bout of demanding exercise, with the most pronounced effect being that on plasma interleukin-6 concentration. However, because of the proposed role of interleukin-6 in the regulation of metabolism, it was unclear whether this represented a reduced response to muscle damage or some form of interaction with the metabolic demands of the activity. Therefore, the aim of the present study was to investigate the effect of the same form of supplementation on a bout of exercise that initiated similar muscle damage but had a low metabolic cost. Fourteen male subjects were allocated to either a placebo (P) or a vitamin C (VC) group. The VC group consumed 200 mg of ascorbic acid twice a day for 14 days prior to a bout of exercise and for the 3 days after exercise. The P group consumed identical capsules that contained 200 mg lactose. Subjects performed 30 min of downhill running at a gradient of -18% and recovery was monitored for up to 3 days after exercise. Plasma VC concentrations in the VC group increased following supplementation. Nevertheless, downhill running provoked a similar increase in circulating markers of muscle damage (creatine kinase activity and myoglobin concentration) and muscle soreness in P and VC groups. Similarly, although downhill running increased plasma interleukin-6, there was no effect from VC supplementation. These results suggest that vitamin C supplementation does not affect interleukin-6 concentrations following eccentric exercise that has a low metabolic component.

Adult↗
PubMed2004

Validation of a new highly standardised, lab-independent whole-blood leukocyte function assay for clinical trials (ILCS).

Physical stress induced in healthy volunteers by the Loughborough intermittent shuttle test (LIST) was used to validate a newly developed whole-blood cell culture system (Instant leukocyte culture system (ILCS). Exercise induced immune modulation was investigated through measurement of cytokine levels after activating leukocytes in peripheral blood ex vivo using the physiologic stimulant lipopolysaccharide (LPS). LPS induced production of three different cytokines, interferon gamma (IFNgamma), interleukin-6 (IL-6), and interleukin-10 (IL-10). IFNgamma levels were significantly decreased (P = 0.02 and P = 0.001 ) and IL-10 levels significantly increased (P= 0.04 and 0.03) after exercise. LPS induced IL-6 production was only marginally further increased by exercise. In conclusion, the ILCS system provided a reliable ex vivo method, showing common as well as subject specific features in the time course of the immune modulation caused by the LIST protocol. This system will be useful for studies of the elderly, where cytokine standardisation is notoriously difficult.

Blood Specimen Collection↗
PubMed2004

Trimethylamine oxide, betaine and other osmolytes in deep-sea animals: depth trends and effects on enzymes under hydrostatic pressure.

Most shallow teleosts have low organic osmolyte contents, e.g. 70 mmol/kg or less of trimethylamine oxide (TMAO). Our previous work showed that TMAO contents increase with depth in muscles of several Pacific families of teleost fishes, to about 180 mmol/kg wet wt at 2.9 km depth in grenadiers. We now report that abyssal grenadiers (Coryphaenoides armatus, Macrouridae) from the Atlantic at 4.8 km depth contain 261 mmol/kg wet wt in muscle tissue. This precisely fits a linear trend extrapolated from the earlier data. We also found that anemones show a trend of increasing contents of methylamines (TMAO, betaine) and scyllo-inositol with increasing depth. Previously we found that TMAO counteracts the inhibitory effects of hydrostatic pressure on a variety of proteins. We now report that TMAO and, to a lesser extent, betaine, are generally better stabilizers than other common osmolytes (myo-inositol, taurine and glycine), in terms of counteracting the effects of pressure on NADH Km of grenadier lactate dehydrogenase and ADP Km of anemone and rabbit pyruvate kinase.

Adaptation, Physiological↗
PubMed2003

Catecholamine responses to high intensity cycle ergometer exercise: body mass or body composition?

The purpose of this study was to compare the sympathoadrenergic and metabolic responses following 30 s of maximal high intensity cycle ergometry exercise when cradle resistive forces were derived from total-body mass (TBM) or fat-free mass (FFM). Increases in peak power output (PPO) and pedal velocity were recorded when resistive forces reflected FFM (953 +/- 114 W vs 1020 +/- 134 W; 134 +/- 8 rpm vs 141 +/- 7 rpm ; P < 0.05). No differences were observed between mean power output (MPO), fatigue index (FI%), work done (WD) or heart rate (HR) when the TBM and FFM protocols were compared. There were no differences between the TBM and FFM protocols for adrenaline (A), noradrenaline (NA) or blood lactate concentrations ([La-]B) recorded at rest, immediately post or 24 h post exercise. However, increases in blood concentrations of A and NA (P < 0.05) were recorded for both the TBM and FFM protocol immediately post exercise. Significant correlations (P < 0.05) were recorded between PPOs, immediate post- exercise NA and [La-]B for both the TBM and FFM protocols. [La-]B levels were also significantly elevated (P < 0.01) immediately post exercise for both the TBM and FFM protocols. The results from this study suggest that greater peak power outputs are obtainable with no subsequent differences in neurophysiological or metabolic stress as determined by plasma A, NA and [La-]B concentrations when resistive forces reflect FFM and not TBM during loading procedures. The findings also indicate that immediate post exercise concentrations return to resting levels 24 h post exercise.

Adult↗
PubMed2001

Blood loss during transurethral resection of the prostate after 3 months of treatment with finasteride.

OBJECTIVES: To study whether pretreatment with finasteride, compared with placebo, reduces the blood loss, operating time, amount of irrigating fluid absorbed, resources used, and other exploratory indexes of extensive surgery during transurethral resection of the prostate (TURP). METHODS: This double-blind, randomized, placebo-controlled, single-center, 6-month pilot study was designed to study the effects of 3 months of finasteride (5 mg daily) on blood loss during surgery in 60 men who required TURP. The prostate size was measured by transrectal ultrasonography, the surgical blood loss was measured by a HemoCue photometer, and fluid absorption was determined by the ethanol method. The microvessel density was counted using microscopic staining and immunoperoxidase techniques. RESULTS: Finasteride significantly reduced the prostate size before TURP (P <0.001 versus placebo). No significant between-group differences were found in blood loss (geometric mean 257 and 268 mL for finasteride versus placebo), fluid absorption, operating time, resection weight, or microvessel density. A positive correlation was found between the blood loss and the resection weight. Exploratory analyses indicated that finasteride might reduce the proportion of patients with high blood loss volumes. For prostates with resection weights greater than or equal to the median (18.6 g), finasteride was associated with less blood loss (median 324 mL, n = 14) than in the controls (median 547 mL, n = 14, P <0.01). CONCLUSIONS: Pretreatment with finasteride may help reduce the blood loss in TURP, except in the smallest resections.

Absorption↗
PubMed2001

The relationship between total-body mass, fat-free mass and cycle ergometry power components during 20 seconds of maximal exercise.

The purpose of this study was to compare the maximal exercise performance of 10 men during friction braked cycle ergometry of 20 s duration when resistive forces reflected total body mass (TBM) or fat free mass (FFM). Fat mass was calculated from the sum of skinfold thicknesses. Increases (P < 0.05) in peak power output (PPO) were found between TBM and FFM (1,015+/-165 W TBM vs 1,099+/-172 W FFM). Decreases (P < 0.05) were observed for the time taken to reach PPO (3.8+/-1.4 s TBM vs 2.9+/-1 s FFM). Pedal velocity increased (P < 0.05) during the FFM protocol (129.4+/-8.2 rpm TBM vs 136.3+/-8 rpm FFM). Rating of perceived exertion (RPE) was also (P < 0.05) greater for FFM (18.4+/-1.6 TBM vs 19.8+/-0.4 FFM). No changes were found for Mean Power Output (MPO), fatigue index (FI) or Work Done (WD) between trials. These findings suggest that high intensity resistive force loading protocols may need to be reconsidered. Results from this study indicate that the active tissue component of body composition needs consideration in resistive force selection when ascertaining maximal cycle ergometer power profiles.

Adult↗
PubMed2001

Acute mountain sickness; prophylactic benefits of antioxidant vitamin supplementation at high altitude.

Acute mountain sickness; prophylactic benefits of Free-radical-mediated damage to the blood-brain barrier may be implicated in the pathophysiology of acute mountain sickness (AMS). To indirectly examine this, we conducted a randomized double-blind placebo-controlled trial to assess the potentially prophylactic benefits of enteral antioxidant vitamin supplementation during ascent to high altitude. Eighteen subjects aged 35 +/- 10 years old were randomly assigned double-blind to either an antioxidant (n = 9) or placebo group (n = 9). The antioxidant group ingested 4 capsules/day(-1) (2 after breakfast/2 after evening meal) that each contained 250 mg of L-ascorbic acid, 100 IU of dl-a-tocopherol acetate and 150 mg of alpha-lipoic acid. The placebo group ingested 4 capsules of identical external appearance, taste, and smell. Supplementation was enforced for 3 weeks at sea level and during a 10-day ascent to Mt. Everest base camp (approximately 5,180 m). Antioxidant supplementation resulted in a comparatively lower Lake Louise AMS score at high altitude relative to the placebo group (2.8 +/- 0.8 points versus 4.0 +/- 0.4 points, P = 0.036), higher resting arterial oxygen saturation (89 +/- 5% versus 85 +/- 5%, P = 0.042), and total caloric intake (13.2 +/- 0.6 MJ/day(-1) versus 10.1 +/- 0.7 MJ/day(-1), P = 0.001); the latter is attributable to a lower satiety rating following a standardized meal. These findings indicate that the exogenous provision of water and lipid-soluble antioxidant vitamins at the prescribed doses is an apparently safe and potentially effective intervention that can attenuate AMS and improve the physiological profile of mountaineers at high altitude.

Adult↗
PubMed2001

Physical exercise and normobaric hypoxia: independent modulators of peripheral cholecystokinin metabolism in man.

The purpose of the present investigation was to determine the independent effects of hypoxia and physical exercise on peripheral cholecystokinin (CCK) metabolism in humans. Thirty-two physically active men were randomly assigned in a double-blind manner to either a normoxic (N; n = 14) or hypoxic (H; n = 18) group. During the acute study, subjects in the H group only participated in two tests, separated by 48 h, which involved a cycling test to exhaustion in normobaric normoxia and normobaric hypoxia (inspired O(2) fraction = 0.21 and 0.16, respectively). In the intermittent study, N and H groups cycle-trained for 4 wk at the same relative exercise intensity in both normoxia and hypoxia. Acute normoxic exercise consistently raised plasma CCK during both studies by 290-723%, which correlated with increases in the plasma ratio of free tryptophan to branched chain amino acids (r = 0.58-0.71, P < 0.05). In contrast, acute hypoxic exercise decreased CCK by 7.0 +/- 5.5 pmol/l, which correlated with the decrease in arterial oxygen saturation (r = 0.56, P < 0.05). In the intermittent study, plasma CCK response at rest and after normoxic exercise was not altered after physical training, despite a slight decrease in adiposity. We conclude that peripheral CCK metabolism 1) is more sensitive to acute changes than chronic changes in energy expenditure and 2) is potentially associated with acute changes in tissue PO(2) and metabolic precursors of cerebral serotoninergic activity.

Adult↗
PubMed2001

General anaesthesia in a patient with undiagnosed "saber-sheath" trachea.

Saber-sheath trachea describes an abnormality in the shape of the trachea caused by underlying disease processes. We present a case of tracheal stenosis in a patient with undiagnosed saber-sheath trachea, in which there was unexpected difficulty in ventilating the lungs despite a good view at laryngoscopy and visually confirmed tracheal intubation.

Anesthesia, General↗
PubMed2001

A potential role for free radical-mediated skeletal muscle soreness in the pathophysiology of acute mountain sickness.

BACKGROUND: It has been suggested that free radicals may be implicated in the pathophysiology of acute mountain sickness (AMS) due to their ability to initiate and propagate cell membrane damage (3). Therefore, the present study was designed to: a) investigate the effects of an expedition to high altitude on metabolic indices of free radical-mediated oxidative stress and assess subsequent implications for skeletal/cardiac muscle damage; and b) determine whether these parameters were different in subjects who developed AMS after gradual ascent to 5100 m (base camp, BC) compared with those who remained healthy. METHODS: There were 19 male volunteers who were examined at rest and after a standardized maximal exercise test at sea level before and after an expedition (SL1/SL2) and during the first morning of arrival at BC. The trek to BC lasted 20+/-5 d. RESULTS: A mild increase in the Lake Louise AMS score was observed by the end of day 1 at BC (p < 0.05 vs. SL1/SL2). Four subjects developed AMS, which in one subject later progressed to high altitude pulmonary and cerebral edema. The serum concentration of lipid hydroperoxides (LH) increased markedly at rest and after maximal exercise at BC (p < 0.05 vs. SL1/SL2) whereas no changes were observed for plasma malondialdehyde (MDA). Resting serum total phosphocreatine kinase activity (CPK) and myoglobin also increased at BC (p < 0.05 vs. SL1/SL2) whereas cardiac troponin I (cTnI) remained stable. The resting pain threshold decreased and exercise-induced muscle soreness subsequently increased at BC (p < 0.05 vs. SL1/SL2). An association was observed between resting LH and myoglobin at BC (r = 0.45, p < 0.05) and the increase in LH was related to the increase in exercise-induced muscle soreness at BC (r = 0.96, p < 0.05). Further correlations were identified between the AMS score on day 1 at BC and: a) resting/exercise LH (r = 0.63, p < 0.05/r = 0.51, p < 0.05); and b) resting pain threshold at BC (r = -0.58, p < 0.05). Furthermore, subjects with AMS on day 1 at BC were characterized by a greater decrease in the resting pain threshold and greater increase in resting LH, CPK and myoglobin compared with subjects without AMS (p < 0.05). Headache, fatigue, insomnia and general apathy were the most frequently reported symptoms of AMS. CONCLUSIONS: Localized free radical-mediated vascular damage of the blood-brain barrier in addition to systemic tissue damage causing overt skeletal muscle soreness may have contributed to the pathophysiology of AMS, the latter through its indirect effects on other non-specific constitutional symptoms such as fatigue and insomnia causing a deterioration in physical performance.

Acute Disease↗
PubMed2001

Intermittent hypoxic training: implications for lipid peroxidation induced by acute normoxic exercise in active men.

Oxidant generation during regular physical exercise training may influence the adaptive responses that have been shown to confer protection against oxidative stress induced by subsequent acute exercise. To examine this, we randomly assigned 32 males to either a normoxic (n=14) or a hypoxic (n=18) group. During the acute phase, subjects in the hypoxic group performed two maximal cycling tests in a randomized double-blind fashion: one under conditions of normoxia and the other under hypoxic conditions (inspired fraction of O(2)=0.21 and 0.16 respectively). During the intermittent phase, the normoxic and hypoxic groups each trained for 4 weeks at the same relative exercise intensity, under conditions of normoxia and hypoxia respectively. During acute exercise under hypoxic conditions, the venous concentrations of lipid hydroperoxides and malondialdehyde were increased, despite a comparatively lower maximal oxygen uptake (VO(2max)) (P<0.05 compared with normoxia). The increases in lipid hydroperoxides and malondialdehyde were correlated with the exercise-induced decrease in arterial haemoglobin oxygen saturation (r=-0.61 and r=-0.50 respectively; P<0.05), but not with VO(2max). Intermittent hypoxic training attenuated the increases in lipid hydroperoxides and malondialdehyde induced by acute normoxic exercise more effectively than did normoxic training, due to a selective mobilization of alpha-tocopherol (P<0.05). The latter was related to enhanced exercise-induced mobilization/oxidation of blood lipids due to a selective increase in VO(2max) (P<0.05 compared with normoxic group). We conclude that lipid peroxidation induced by acute exercise (1) increases during hypoxia; (2) is not regulated exclusively by a mass action effect of VO(2); and (3) is selectively attenuated by regular hypoxic training. Oxidative stress may thus be considered as a biological prerequisite for adaptation to physical stress in humans.

Adult↗