Jyotirmoy Nandi

Diagnostic accuracy of serum hyaluronic acid, FIBROSpect II, and YKL-40 for discriminating fibrosis stages in chronic hepatitis C.

OBJECTIVES:Noninvasive serum markers of liver fibrosis are being used as an alternative to liver biopsy. Currently available tests distinguish, with accuracy, only absent/minimal fibrosis (Ishak stages 0–1) and advanced fibrosis/cirrhosis (Ishak stages 4–6), but not intermediate fibrosis (Ishak stages 2–3). Our aim was to evaluate the diagnostic accuracy of hyaluronic acid (HA), FIBROSpect II (FS-II), and YKL-40 (chondrex, human cartilage glycoprotein-39) in various clinically important categories of fibrosis, and further correlate these serum markers with digital quantification of fibrosis (DQF) and Ishak stages.METHODS:Serum HA, YKL-40, and FS-II were retrospectively assessed and correlated with Ishak stages and DQF scores in 75 patients with chronic hepatitis C (HCV). Spearmans rho statistics assessed relationships among all parameters, and receiver operator characteristic curves evaluated accuracy of each parameter when compared to the Ishak stages.RESULTS:All three serum markers and DQF correlated highly with one another (P ≤ 0.01) and with Ishak stages of fibrosis. Among the serum markers, HA was effective in discriminating between Ishak stages 0–1 and Ishak stages 2–3 compared with FS-II, with an area under the curve of 0.76 versus 0.66 and a false-positive rate of 0.33 versus 0.67, respectively. All three serum markers predicted advanced fibrosis and cirrhosis. YKL-40 had the highest false-positive rates in all categories of fibrosis.CONCLUSIONS:HA can be utilized as a reliable surrogate marker in distinguishing three clinically relevant stages of fibrosis: absent/minimal, intermediate, and advanced/cirrhosis. HA should be considered as a cost-effective alternative to other serum markers for staging fibrosis and for determining the timing and selection of HCV treatment.

Dietary supplementation of nucleotides and arginine promotes healing of small bowel ulcers in experimental ulcerative ileitis

We previously showed that intravenous totalparenteral nutrition supplemented with nucleosides andnucleotides (NS/NT) promoted ulcer healing in rats withindomethacin-induced ileitis. The present study evaluated whether dietary NT supplementationwould similarly affect ulcer healing in this model.Female Lewis rats were randomized into either control orexperimental groups receiving yeast RNA containing NT or arginine, glutamine, fish oil, guar gum,or a combination of yeast RNA + arginine diets. Ileitiswas induced by two doses of indomethacin (7.5 mg/kg)administered subcutaneously 24 hr apart. Ulcer number and length were determined at 4, 8, and 14 daysafter induction of ileitis. Ileal villous and cryptlength, crypt-villous ratio, and bromodeoxyuridine(BrdU) labeling were studied in the control and yeast RNA-supplemented diet groups. Ileal ulcerationwas present in all groups at 4 and 8 days and was almosthealed by 14 days. Rats receiving yeast RNA, arginine,and yeast RNA + arginine diets showed a significant decrease in ulcer number (56%, 28%, and 34%,respectively) and length (67%, 41%, and 48%,respectively) compared to controls at 8 but not at 4days. Glutamine, fish oil, and guar gum had no effect onulcer healing at 4, 8, or 14 days. Among thehistological parameters, a significant decrease in cryptlength in the yeast RNA-supplemented group at 8 dayssuggested an acceleration of the healing process and restoration to a near-normal crypt-villousarchitecture. We conclude that the yeast RNA, arginine,and yeast RNA + arginine diets accelerated ulcerhealing, as indicated by decreased ulcer number andlength. We postulate that the underlying mechanism(s)contributing to ulcer healing may be related, in part,to increased cell proliferation.

Central mechanisms involved with catabolism

Purpose of reviewCatabolism conjures up an end-metabolic process in which muscle and fat tissue are broken down into their constituent parts to provide nutrients for the body, secondary to a noxious stimulus that prevents the organism from adequately nourishing itself. However, catabolism is a primary event, initiated in the brain in response to perceived or real stresses or noxious stimuli, which has a secondary effect of inhibiting food intake and consequently the break down of skeletal muscle and adipose tissues to provide nutrients for the body to survive. Recent findingsThis is achieved via a cascade of neurohormonal monoaminergic and peptidergic mediators in the central nervous system, invoking the cortex, the limbic system and the hypothalamus. Among the most detailed mediators studied are corticotropin-releasing factor and serotonin which, via the hypothalamic-pituitary-adrenal axis and the sympathetic and parasympathetic nervous system, stimulate catecholamines and cortisol and inhibit anabolic hormones, insulin, leptin, ghrelin, including neuropeptide Y and other neuropeptides, among them the paracrine-acting cytokines. Simultaneously, there occurs stimulation of the counter-regulatory hormones cortisol, glucagon and the melanocortin family of neuropeptides. SummaryThe net effect is anorexia, with the inhibition of food intake, body weight loss, delayed gastric emptying and functions, the stimulation of gluconeogenesis, glycogenolysis and ketogenesis as sources of metabolic fuel, which if unabated leads ultimately to cachexia. The use of antagonists and the removal of stress or noxious stimuli experimentally test different pathways of this dynamic metabolic picture. Several studies have demonstrated important progress towards our understanding of the central mechanisms involved in anorexia and weight loss, which we summarize in this review.

Hyperbaric oxygenation therapy alleviates chronic constrictive injury-induced neuropathic pain and reduces tumor necrosis factor-alpha production.

BACKGROUND: The development of hyperalgesia and allodynia after chronic constrictive injury (CCI) is associated with significantly increased tumor necrosis factor (TNF)-&agr; and interleukin (IL)-1&bgr;. Theoretically, if the production of TNF-&agr; and/or IL-1&bgr; could be reduced, neuropathic pain syndrome may be alleviated. Recently, a beneficial effect of hyperbaric oxygenation therapy (HBOT) in the treatment of pain disorders has been suggested. Our present study was designed to examine the hypotheses that (1) CCI-induced neuropathic pain may be associated with increased production of TNF-&agr; and IL-1&bgr;, (2) HBOT may alleviate CCI-induced neuropathic pain, and (3) the alleviated neuropathic pain may be associated with reduced production of TNF-&agr; and/or IL-1&bgr;. METHODS: Male rats (weighing 250–300 g) were anesthetized with ketamine and xylazine. The common sciatic nerve was exposed through the biceps femoris. Proximal to the sciatic’s trifurcation, 4 ligatures were loosely tied around the nerve. In the sham group, an identical dissection was performed without ligation of the sciatic nerve. Mechanical allodynia and cold allodynia were tested by von Frey filament stimulation and the spread of acetone, respectively. HBO rats (n =18) were exposed to pure oxygen for 1 hour at 2.4 atm once a day. Non-HBO (n =18) and sham rats (n =6) were placed in the HBOT chamber breathing air. TNF-&agr; and IL-1&bgr; in the sciatic nerve were assayed with ELISA. The presence of TNF-&agr; protein in homogenates was verified by Western blot analysis. RESULTS: CCI induced significant cold and mechanical allodynia as measured after CCI on days 4 and 7. The cold allodynia response frequency was significantly lower in HBO rats than in non-HBO rats. The values were 20% ± 1.6% vs 50% ± 4.5% on day 4 and 40% ± 4.6% vs 70% ± 4.5% on day 7 (F =87.42, confidence interval [for the difference between HBO and non-HBO]=29.612 ± 8.781, P < 0.05 for day 4 and day 7). The threshold of mechanical allodynia significantly increased in HBO rats compared with non-HBO rats. The values were 6.20 ± 0.9 vs 4.1 ± 1.0 g on day 4 and 3.8.2 ± 0.5 vs 2.3 ± 0.4 g on day 7 (F =18.8, confidence interval [for the difference between HBO and non-HBO]=1.806 ± 1.171, P < 0.05 for day 4 and day 7). TNF-&agr; content was significantly higher in non-HBO rats than in sham rats on day 4 (17.89 ± 0.83 vs 10.66 ± 1.1 pg/mg protein, P < 0.05) and day 7 (18.97 ± 1.57 vs 9.09 ± 1.5 pg/mg protein, P < 0.05). HBOT significantly reduced TNF-&agr; content to near the level in sham rats, which was 10.94 ± 2.78 and 11.32 ± 2.98 pg/mg protein on day 4 (P < 0.05 versus non-HBO) and 7 (P < 0.05 versus non-HBO), respectively. Western blot analysis confirmed the presence of proteins with molecular weights of 51 kDa in the rat sciatic nerve homogenates. IL-1&bgr; content was also significantly higher in non-HBO rats than in sham rats on day 4 (636 ± 74 vs 256 ± 31 pg/mg protein, P < 0.05) and on day 7 (687 ± 89 vs 288 ± 35 pg/mg protein, P < 0.05). HBOT had no effect on IL-1&bgr; content, which was 671 ± 85 pg/mg protein on day 4 and 672 ± 75 pg/mg protein on day 7 in HBO rats (P =not significant versus non-HBO rats). CONCLUSION: These data show that HBOT alleviates CCI-induced neuropathic pain and inhibits endoneuronal TNF-&agr; production, but not IL-1&bgr; in CCI-induced neuropathic pain. Reduced TNF-&agr; production may, at least in part, contribute to the beneficial effect of HBOT.

Inhibition of TNF-α Improves Indomethacin-Induced Enteropathy in Rats by Modulating iNOS Expression

TNF-α, including other proinflammatory cytokines alone or in combination, induces iNOS expression and upregulates inflammatory responses. We evaluated the relationship between TNF-α and iNOS expression in indomethacin-induced jejunoileitis in male Sprague–Dawley rats. Rats were fed a daily dose of a phosphodiesterase inhibitor—either theophylline or pentoxifylline—for 2 days. Jejunoileitis was induced with two subcutaneous injections of indomethacin (7.5 mg/kg) 24 hr apart and theophylline or pentoxifylline continued for 12 hr or 4 days. Other rats received a single intraperitoneal injection of anti-TNF-α monoclonal antibody (TNF-Ab) 30-min before indomethacin. At 4 days TNF-Ab, theophylline, or pentoxifylline treatment significantly decreased indomethacin-induced ulceration, myeloperoxidase activity, and disease activity index. Although indomethacin significantly increased serum TNF-α and nitrate/nitrite levels over the control value as early as 12 hr, iNOS expression was detected only after 4 days. Serum IL-1β level did not change at 12 hr but increased fourfold at 4 days. Treatment with TNF-Ab, theophylline, or pentoxifylline significantly reduced serum/tissue TNF-α, IL-1β, nitrate/nitrite, and iNOS expression. The downregulation of nitrate/nitrite by these inhibitors suggests that TNF-α modulates iNOS expression.

Beneficial effect of hyperbaric oxygen pretreatment on lipopolysaccharide-induced shock in rats.

1. We investigated the effect of hyperbaric oxygenation (HBO2) pretreatment on the production of exhaled nitric oxide (ENO) and the expression of lung inducible nitric oxide synthase (iNOS) by Escherichia coli lipopolysaccharide (LPS)‐induced shock in an experimental rat model.

EFFECTS OF HYPERBARIC OXYGEN ON GLUCOSE, LACTATE, GLYCEROL AND ANTI‐OXIDANT ENZYMES IN THE SKELETAL MUSCLE OF RATS DURING ISCHAEMIA AND REPERFUSION

1 Hyperbaric (HBO2) and topical oxygen represent two accepted options to oxygenate tissues. The aim of the present study was to investigate the effect of HBO2 on energy metabolism and anti‐oxidant enzymes in a rat model of ischaemia–reperfusion (IR) skeletal muscle injury. 2 In the first study, 16 rats were randomized to a HBO2‐treated group (Group 1; n = 8) and an untreated group (Group 2; n = 8). Under general anaesthesia, right hind limb ischaemia was produced by application of a rubber‐band tourniquet for 3 h. After 2 h ischaemia, Group 1 rats received HBO2 during the last hour of ischaemia. The HBO2 consisted of 100% oxygen delivered at 282.8 kPa absolute pressure. Group 2 rats were not treated. Following the ischaemic period, the tourniquet was released for 1 h. A microdialysis probe was used to sample lactate, glucose and glycerol concentrations in the muscle extracellular tissue every 15 min throughout each experiment. 3 In the second study, 24 rats were randomized into four groups (n = 6 each). The first two groups were subjected to the IR injury protocol outlined above and either treated (Group 1) or untreated (Group 2) with HBO2. Group 3 rats were anaesthetized, did not undergo IR injury, but underwent HBO2 treatment. Group 4 rats were anaesthetized but did not undergo either IR injury or HBO2 treatment. At end of each experiment, the biceps femoris muscle was removed and assayed for superoxide dismutase (SOD) and catalase (CAT) activity. Malondialdehyde (MDA) was measured to estimate the extent of membrane lipid peroxidation. 4 Three hours of skeletal muscle ischaemia resulted in a gradual decrease in the glucose concentration and a gradual increase in the lactate concentration within the extracellular fluid of the affected skeletal muscle tissue. Treatment with HBO2 had no effect on the glucose concentration; however, HBO2 significantly attenuated the ischaemia‐induced increase in lactate and glycerol. In both groups, glucose concentration increased rapidly during reperfusion; glucose concentration returned to pre‐ischaemic levels 15 min after reperfusion both with and without HBO2. 5 Catalase activity and MDA increased significantly after 1 h of reperfusion. The HBO2 attenuated the reperfusion‐induced increase in CAT activity and MDA. 6 The results of the study suggest that HBO2 may have some beneficial effect by decreasing lactate and glycerol levels and modulating anti‐oxidant enzyme activity in postischaemic skeletal muscle in our rat model of tourniquet‐induced IR skeletal muscle injury.

Anorexia in space and possible etiologies: An overview

Space travelers experience a flight duration-dependent loss in weight and body mass while in a microgravity environment, despite the absence of increased energy expenditure. Anorexia in space can lead to in-flight caloric deficits of 1330 kcal per 70 kg astronaut per day in the presence of abundant food and has a critical effect on endurance and performance. Microgravity, alterations in the light-and-dark cycle, and exposure to radiation energy are the environmental stresses believed to influence appetite, food intake, and gastrointestinal function during space flight. Review of data and recent studies in rodents during microgravity showed a release of stress hormones and complex neuroendocrine and physiologic changes involving the modulation of hypothalamic activity, food intake-related hormones, and cytokines. The shift of dietary preference to carbohydrates, which occurs in astronauts, denotes a stress physiologic response and augments free-plasma tryptophan concentration in the brain, the precursor of the potent anorexic agent, serotonin (5-HT). Alterations of other neuroendocrine mediators, including corticotropin-releasing factor (CRF), coordinate the stress response, leading to a decrease in appetite and gastrointestinal function. Our laboratories used the antiorthostatic tail-suspension technique to successfully mimic some of these anorexia-related stress responses and to directly demonstrate the role of 5-HT in microgravity-related decreased food intake and delayed gastric emptying. Further rodent studies from our laboratories demonstrated the adverse effect of altered dark-and-light cycles on food intake and body weight. Radiation energy, through its documented effects on appetite, probably contributes to the decreased caloric intake by astronauts. Modulation of hypothalamic activity, 5-HT, and CRF play a critical role in anorexia related to microgravity and circadian rhythm alterations. Specific gene knockout mice (e.g., 5-HT or CRF and their respective receptors) may prove fruitful in defining the pathways by which anorexia in space occurs. An understanding of these pathophysiologic problems as they relate to appetite, food intake, gastric emptying and gastrointestinal function, sufficiently to derive successful practical solutions, may lead to a quantitative enhancement of physiologic well-being and performance status, serving as a productive countermeasure in space.

Hyperbaric Oxygenation Ameliorates Indomethacin-Induced Enteropathy in Rats by Modulating TNF-α and IL-1β Production

The effect of hyperbaric oxygenation (HBO2) was investigated in a rat model of indomethacin-induced enteropathy. Enteropathy was induced by two subcutaneous injections of indomethacin (7.5 mg/kg) 24 hr apart. Six groups of rats (n=8) were treated with and without HBO2 (100% oxygen at 2.3 atm absolute) for 1 hr once or twice a day for 2 or 5 days. Disease activity index (DAI) and total ulcer length were measured. Other rats were randomized into two groups (n=16) with and without HBO2 (1 hr once a day) and four rats were killed in each group at 12, 24, 48, and 72 hr after the final injection of indomethacin. Serum and intestinal mucosal TNF-α, IL-1β, myeloperoxidase (MPO), and iNOS expression was measured. HBO2 treatment significantly attenuated indomethacin -induced intestinal ulceration and improved DAI. Indomethacin increased MPO activity and iNOS expression, and these were reduced by HBO2 treatment, with a concomitant reduction in TNF-α and IL-1β. Our data suggest that HBO2 treatment has a beneficial effect on indomethacin-induced enteropathy and this effect is possibly mediated by decreased production of TNF-α and IL-1β.

Gastric acid is the key modulator in the pathogenesis of non‐steroidal anti‐inflammatory drug‐induced ulceration in rats

1. In the present study, we investigated the role of gastric acid (GA) secretion on non‐steroidal anti‐inflammatory drug (NSAID)‐induced ulcerogenesis in vivo. Rats were administered single oral doses of selective cyclo‐oxygenase (COX)‐1 (SC‐560; 2.5 mg/kg), COX‐2 (DFU; 25 mg/kg) or non‐selective COX (indomethacin; 25 mg/kg) inhibitors. Three groups (basal, histamine‐stimulated and histamine with lansoprazole) were pylorus ligated 2 h after inhibitor administration and killed 2 h later. Another group without pylorus ligation received only inhibitors and was killed after 18 h.