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Biomedical subjects

M M Meguid

Publications and source records attributed to M M Meguid.

At least 91 records · Page 5Linked to original sources
PubMed1996

Comparison of long-term feeding pattern between male and female Fischer 344 rats: influence of estrous cycle.

We studied the effect of gender on food intake, meal number, and meal size in eight 10-wk-old female and seven age-matched male Fischer 344 rats for 44 consecutive days. Although food intake (g/100 g body wt) was similar in males and females (5.42 +/- 0.10 vs. 5.13 +/- 0.13 g food.day-1.100 g body wt-1, respectively; not significant), weight gain in males was approximately seven times greater than in female rats (1.49 +/- 0.07 vs. 0.21 +/- 0.03 g/day, respectively; P < 0.001). During this time, males had a relatively constant food intake. They increased their meal size but decreased their meal number. In female rats, food intake was relatively stable for the duration of the study, despite cyclically and reciprocally recurring changes in meal number and meal size, which are synchronized with the estrous cycle. Data confirm that net food intake is a dynamic process and suggest that, in the rat, the homeostasis of food intake in response to external as well as internal stimuli is maintained via the modulation of meal number and size.

Animals↗
PubMed1996

Mode of food intake reduction in Lewis rats with indomethacin-induced ulcerative ileitis.

The mechanism of anorexia in inflammatory bowel disease is poorly understood. To gain insight into possible pathophysiologic mechanisms, the feeding indices and food intake were studied in an animal model of Crohn's disease. The anorexia of indomethacin-induced ulcerative ileitis was compared with that of the well-known anorexia of total parenteral nutrition (TPN). Forty-five female Lewis rats were randomized to four groups: Control, Indomethacin, Indomethacin + TPN, and TPN. Feeding indices and food intake were continuously measured using the Automated Computerized Rat Eater Meter. Interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF-alpha), prostaglandin E2 (PGE2), and leukotriene B4 (LTB4) were assayed in plasma, mononuclear cell culture, or ileum to determine their role in mediating anorexia. In the TPN group, spontaneous food intake (SFI) decreased (52%; p < 0.05), primarily via reduction in meal number (MN, 54%; p < 0.05) and, to a lesser extent, meal size (MZ, 35%; p < 0.05). In comparison, in the Indomethacin group SFI decreased (74%; p < 0.05) primarily via reduction in MZ (67%, p < 0.05); MN also decreased but to a lesser extent (27%; p < 0.05). In the Indomethacin + TPN group, SFI decreased (55%; p > 0.05) primarily via reduction in MN (79%; p < 0.05), whereas MZ decreased slightly (19%; p < 0.05). Only in the Indomethacin group were IL-1 alpha and TNF-alpha detected in the mononuclear cell culture and plasma, respectively. In the Indomethacin group, an inverse correlation existed between MZ and TNF-alpha (p < 0.05). In the Indomethacin group, IL-1 alpha, PGE2, and LTB4 concentrations did not correlate with feeding indices. SFI reduction in this model was mediated primarily via a decrease in MZ. TNF-alpha is proposed to mediate this effect and TPN was shown to overcome the effect on MZ.

Animals↗
PubMed1995

Temporal changes in meal number and meal size relationship in response to rHu IL-1 alpha.

Peripherally infused interleukin-1 reduces food intake. Its temporal and selective effects on meal number and meal size were investigated in seven rats continuously infused for 3 days with recombinant human interleukin-1 alpha (rHu IL-1 alpha; 3 micrograms day-1, i.v.). Food intake decreased significantly during the first two infusion days, and was brought about by first the early reduction of meal number, followed by meal size with a 1 day delay. The primary effect of rHu IL-1 alpha was seen during the dark cycle. After the infusion was stopped, meal number recovered most quickly, followed by a lag in recovery of meal size. We conclude that rHu IL-1 alpha influenced food intake primarily via an effect on meal number, which responds more rapidly than a decrease in meal size, thereby inducing an immediate decrease in food intake.

Animals↗
PubMed1995

Hepatic vagus does not mediate IL-1 alpha induced anorexia.

Peripherally infused interleukin-alpha (IL-1 alpha) reduces food intake. Since the innervated liver modulates eating activity via the vagus, we investigated the role of the hepatic vagus in the etiology of IL-1 alpha induced anorexia. Ten male Fischer 344 rats were randomly assigned to hepatic vagotomy (HX-IL-1 group) or sham operation (Sham-IL-1 group), and an internal jugular catheter was inserted in all rats. Another six sham operated rats receiving normal saline i.v. throughout the study period served as general controls. After a 10-day recovery period, HX-IL-1 and Sham-ILI-1 rats were infused with 3 micrograms day-1 of IL-1 alpha for 3 days, followed by a 4 day infusion of saline. During the IL-1 alpha infusion, food intake was reduced at a similar rate and by a similar amount in both vagotomized and sham-operated rats. When IL-1 alpha infusion was stopped, food intake normalized at a similar rate in both HX-ILI-1 and Sham-IL-1 groups. These data indicate that the hepatic vagus is not involved in the etiology of IL-1 alpha induced anorexia.

Animals↗
PubMed1995

LHA dopaminergic activity in obese and lean Zucker rats.

Microdialysis was performed to quantitate lateral hypothalamic dopamine (LHA DA) release before, during and after a single meal in food-deprived obese and lean Zucker rats to examine our hypothesis that an abnormally high dopamine activity may exist in the LHA of obese Zucker rats. Food consumption after food deprivation, was significantly greater in obese than in lean rats (4.1 +/- 0.2 and 2.3 +/- 0.4 g, respectively; (p < 0.05). Mean basal dopamine level was significantly higher in obese than in lean rats (12.0 +/- 0.3 and 10.5 +/- 0.3 pg in 10 microliters dialysates, respectively; p < 0.05). Dopamine release during eating was greater in obese than in lean rats (159.1 +/- 6.8% and 135.4 +/- 3.6% of baseline level, respectively; p < 0.05). After eating, the dopamine level returned to that before (105.6 +/- 4.5% in obese rats and 101.9 +/- 4.0% in lean rats) within the first 20 min sample. Data suggest that there may exist an inherently higher LHA DA 'threshold' level in obese Zucker rats and that until it is reached, food intake continues. This higher 'threshold' level may be responsible for their unique feeding behavior and is probably a contributory factor to their development of obesity.

Animals↗
PubMed1995

Correlation between food intake and CSF IL-1 alpha in anorectic tumor bearing rats.

Postulating that central IL-1 is involved in the pathogenesis of cancer anorexia we measured IL-1 alpha in cerebrospinal fluid (CSF) from anorectic tumor bearing (TB) rats and non-tumor bearing controls, and correlated their CSF IL-1 alpha with food intake and tumor weight. Food intake in controls was significantly higher than that in anorectic TB rats. Eight of the 13 anorectic TB rats had detectable CSF IL-1 alpha; no CSF IL-1 alpha was detected in controls. In anorectic TB rats a negative correlation existed between CSF IL-1 alpha and food intake and a positive correlation between CSF IL-1 alpha and tumor weight. Data suggest a link between CSF IL-1 alpha and the pathogenesis of cancer anorexia.

Animals↗
PubMed1995

An electrophysiological study on amino acid sensors in the hepato-portal system in the rat.

The existence of amino acid sensors sensitive to arginine, alanine, leucine and glycine in the hepato-portal region was previously reported based on recording of the afferent signals from the hepatic branch of the vagus nerve. The present study was carried out to investigate the effects of fifteen different amino acids on the activity of the vagal hepatic afferents. Intraportal administration (10 mM, 0.1 mL) of alanine, arginine, histidine, leucine, lysine, serine, tryptophane and valine increased vagal afferent discharge rate, and that of cysteine, glycine, isoleucine, methionine, phenylalanine, proline and threonine suppressed it. The results indicate the existence of two groups of amino acids sensors which exhibit excitatory or inhibitory effect on the afferent activity of the hepatic branch of the vagus nerve. The change in afferent activity to the hypothalamus may affect reflex regulation of the visceral functions and thereby influence appetite.

Afferent Pathways↗
PubMed1995

Effects of TPN on brain, liver, and food intake in rats.

Postulating that total parenteral nutrition (TPN) has a direct metabolic effect in the brain which may be similar to that in the liver, we studied the effects of TPN on brain glycogen and triglyceride in rats. Control rats (n = 24) received normal saline via jugular catheter for 18 days; TPN rats (n = 24) had normal saline for 10 days and then TPN-100 for 4 days, followed by normal saline for 4 more days. TPN-100 (caloric ratio glucose: fat:amino acid = 50:30:20) provided 100% of the rat's daily caloric needs. Chow and water were available ad libitum during the study. Eight rats from each group were sacrificed after 1 and 4 days of TPN-100, and 4 days after stopping TPN-100. Glycogen in brain and liver glycogen, triglyceride, and glycogen synthetase and phosphorylase were measured, as were plasma glucose and insulin. Data were evaluated using Student's t test. With TPN, the following occurred: (a) an 85% decrease (P < 0.05) of spontaneous food intake; (b) an elevated plasma glucose; (c) a three- to fivefold increase (P < 0.01) in plasma insulin; (d) a 23% increase (P < 0.05) in whole brain glycogen but a 22-33% decrease (P < 0.05) in liver glycogen; (e) liver glycogen synthetase and phosphorylase activity were unchanged while whole brain glycogen synthetase activity decreased by 27% (P < 0.05) and phosphorylase activity increased by 10-16%; and (f) whole brain triglyceride content did not change, although there was a 155-241% increase (P < 0.01) in liver triglyceride.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Surfeit calories during parenteral nutrition influences food intake and carcass adiposity in rats.

The relationship between surfeit caloric consumption during intravenous infusion of a parenteral nutrition solution providing 100% daily caloric needs (PN-100; glucose:fat:amino acid = 50:30:20), carcass adiposity, and postinfusion food intake was evaluated. Rats received saline (control) or PN-100 for 4 days via jugular vein. PN-100 rats were either allowed or denied access to chow during the infusion period. When food was available during the 4 days of PN-100, total cumulative caloric intake, eaten and infused, was 40% higher than controls (p < 0.01). Percent carcass adiposity was increased from 8.8% to 11.6% (p = 0.04), and there was a 3-day delay before food intake returned to baseline. When caloric intake was limited to that provided by PN-100, carcass adiposity was not increased and food intake was 86% of baseline during the first 24 h after stopping PN-100. Delayed return of normal food intake following PN-100 is the likely consequence of excess caloric ingestion during the PN-100 infusion period. The surfeit caloric intake resulted in increased carcass adiposity.

Adipose Tissue↗
PubMed1995

Effects of different types of isocaloric parenteral nutrients on food intake and metabolic concomitants.

Whether spontaneous food intake (SFI) is controlled by infused nutrient type or its caloric content, irrespective of nutrient type, was investigated. Rats were infused for 4 days with isocaloric solutions of different nutrient type but sharing the same intermediary metabolic oxidative pathway, providing 25% of daily caloric needs. One parenteral solution was a glucose, fat and amino acid mix (TPN-25%); the other provided ketone bodies (TRI-3.5%). Effects of parenteral infusions on SFI and metabolic concomitants were compared and contrasted to that in a group of orally fed rats. Both infusions reduced SFT by 50%. Rats receiving TRI-3.5% had lower blood glucose and insulin concentrations, but increased hepatic glycogen content compared to TPN-25% or orally fed rats. No differences in hepatic triglycerides occurred between the three groups. However, serum free fatty acids were significantly lower in TRI-3.5% and in TPN-25% groups vs. fed rats. Data indicate food intake suppression is mediated by caloric content rather than nutrient type, suggesting that a mediator of SFI regulation could be at the citric acid cycle level.

Amino Acids↗
PubMed1995

Effects of fasting, intermittent feeding, or continuous parenteral nutrition on rat liver and brain energy metabolism as assessed by 31P-NMR.

We wanted to determine what happens to brain PCr and ATP relative to that in liver during a series of dietary manipulation consisting of a severe fast, during eating (when nutrients are intermittently supplied), and during and after PN-100, when an excess amount of nutrients are continuously supplied, using 31P-NMR spectroscopy, in rats randomized to a Fast or Fed group in which energy was provided either as chow or as PN-100. Liver ATP concentration, and brain and liver 31P-nuclear magnetic resonance (NMR) spectras were measured serially. Brain energy metabolism was not different between groups and among days. In contrast, Fasted group showed increased liver ATP/Pi ratio and decreased ATP concentration and ATP/phosphomonoester ratio, there being no difference between Fed and PN-100 groups. Data suggest that brain energy metabolism is maintained regardless of whether energy is supplied intermittently or continuously, and during a negative caloric intake period, brain energy metabolism is quantitatively preserved, suggesting that ATP production by liver is subservient to brain ATP state.

Adenosine Triphosphate↗
PubMed1995

Continuous systemic interleukin-1 alpha infusion suppresses food intake without increasing lateral hypothalamic dopamine activity.

In addition to its immunomodulatory action, interleukin-1 (IL-1 alpha) induces anorexia centrally. Whether IL-1-induced anorexia is mediated by dopaminergic activity in the lateral hypothalamic area (LHA) was investigated by using microdialysis in freely moving rats. After recovery from jugular vein catheterization and LHA cannulation, rats had a microdialysis probe inserted into the LHA. Microdialysis samples were continuously collected in control rats not infused, and in IL-1-treated rats during and after a 24 h continuous systemic infusion of 6 micrograms IL-1 alpha. IL-1 alpha significantly suppressed food intake from 13.6 +/- 0.1 g to 4.3 +/- 0.8 g (p < 0.001), but there was no significant difference in dopamine concentration in the LHA dialysates before, during and after IL-1 alpha infusion relative to controls. Although IL-1 alpha has been shown to act centrally, our results suggest that the anorexic effect of IL-1 alpha is not mediated through dopaminergic activity in the LHA.

Animals↗
PubMed1995

Eating induced rise in LHA-dopamine correlates with meal size in normal and bulbectomized rats.

Dopaminergic function in the lateral hypothalamic area (LHA) is important for processing intrinsic and extrinsic feeding related information. Brain microdialysis was used to examine if dopamine release in the LHA correlates with meal size in normal and bulbectomized rats. Food-deprived bulbectomized rats ate significantly less food (1.7 +/- 0.1 g) than food-deprived sham operated rats (3.1 +/- 0.5 g, p < 0.05), accompanied by a lesser increase in LHA-dopamine release (150.6 +/- 4.9% vs. 195.1 +/- 13.9, p < 0.02). LHA-dopamine release was significantly higher in rats which ate a full meal (2.9 +/- 0.1 g) than in rats which ate half a meal (1.5 +/- 0.1 g, p < 0.05), being 155.9 +/- 7.8% vs. 131.0 +/- 4.9% (p < 0.05) in food-deprived normal rats. Data suggest that dopamine release in the LHA correlates to the quantity of food consumed during a meal.

Animals↗
PubMed1995

Tumor necrosis factor-alpha and total parenteral nutrition-induced anorexia.

BACKGROUND: We hypothesize that total parenteral nutrition (TPN) induces anorexia by an increase in anorexigenic cytokines (factors with central action via the hypothalamus) and tested this hypothesis by measuring changes in food intake and cytokines in response to TPN. METHODS: Fischer rats with an internal jugular catheter and ad libitum food received saline solution for 10 days. On day 11, rats were randomized to TPN (G:F:AA = 50:30:20) for 4 days (days 11 through 14); control rats received on saline solution for 5 days. On day 14, one half of the TPN group was switched back to saline solution for 1 day. Daily food intake was measured. On day 14 in one half of all rats and on day 15 in the remaining, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 alpha were measured in plasma and cerebrospinal fluid (CSF). Spontaneous in vitro TNF-alpha and IL-1 alpha were also measured in peripheral blood mononuclear cells. RESULTS: With TPN, an 80% decrease (p < 0.01) in food intake occurred; plasma TNF-alpha increased (78 +/- 9 pg/ml vs undetectable; p < 0.001), and IL-1 alpha was undetectable. Spontaneous in vitro TNF-alpha and IL-1 alpha production were unchanged. Stoppage of TPN led to return toward normal of food intake and plasma TNF-alpha. TNF-alpha and IL-1 alpha in CSF were undetectable in both groups during and after TPN. CONCLUSION: Increase in plasma TNF-alpha with no increase in CSF-TNF-alpha during TPN, when food intake decreased, suggests an association between TPN and TNF-alpha but not necessarily cause and effect.

Animals↗
PubMed1995

Pathogenesis-based treatment of recurring subareolar breast abscesses.

BACKGROUND: When a subareolar breast abscess (SBA) is incised and drained, an extraordinarily high frequency of recurrence is noted. METHODS: To develop a pathogenesis-based treatment plan, 24 women with a total of 84 abscesses were monitored. RESULTS: In nine women SBA was under the left areola, under the right, in 7 and in eight the SBA occurred either simultaneously or sequentially under both areolae. In 11 of 24 patients a chronic lactiferous duct fistula also existed. In four of 24 patients four SBAs were treated with antibiotics; alone; all recurred. In 16 of 24 patients initial treatment was incision and drainage plus antibiotics; all recurred. When the abscess plus the plugged lactiferous duct was excised, there were no recurrences; however, in four patients a new abscess in a different duct occurred, which was treated by en bloc resection of all subareolar ampullae, without further recurrence. Patients with a fistulous tract had the fistula, its feeding abscess, and its plugged lactiferous duct excised, without recurrence. In first time SBA the organism was usually staphylococcus; in recurrences mixed flora was isolated. Pathologic findings ranged from squamous metaplasia with keratinization of lactiferous ducts to chronic abscess. CONCLUSIONS: The cause of SBA is plugging of lactiferous duct within the nipple by keratin. To prevent recurrence the abscessed ampulla with its plugged proximal duct needs excision.

Abscess↗
PubMed1995

Alterations in extracellular GABA in the ventral hypothalamus of rats in response to acute glucoprivation.

gamma-Aminobutyric acidergic (GABA) mechanisms in the ventral hypothalamus may be involved in counterregulatory responses to glucoprivic episodes. Microdialysis probes (1 mm) were placed into the ventromedial hypothalamus (VMH) or lateral hypothalamus (LHA) of male Sprague-Dawley rats 3.5 h before 2-deoxy-D-glucose (2-DG) administration (200 mg/kg i.v.). Probes were perfused (2 ml/min) with Ringer solution, and samples were collected every 10 min from 30 min before to 60 min after 2-DG. By 30 min after 2-DG, GABA concentration in VMH dialysate increased in a bimodal fashion to 204 +/- 36% (P < 0.01) of baseline, and GABA concentration in LHA dialysate decreased to 77 +/- 4% (P < 0.01) of baseline. The changes in dialysate GABA concentrations occurred concurrently with the animals eating and returned to baseline by 60 min. When animals were denied access to food after 2-DG, the decrease in LHA GABA was not apparent and VMH GABA remained approximately 15% above baseline at the end of the sample period. The results of the present study provide evidence that GABAergic systems in the ventral hypothalamus are responsive to alterations in glucose status.

Acute Disease↗
PubMed1995

Effects of arginine-lysine mixture, glucose and ATP on the autonomic outflows to the thymus and spleen.

Effect of arginine-lysine mixture, glucose and ATP on the efferent activities of the vagal thymic branch and splenic nerve were studied in urethane anesthetized rat. In male Wistar rats jugular vein was cannulated for drug administration. In one group the thymus was exposed and a nerve filament of the central cut end of vagal thymus was isolated. In another group a filament was isolated from that of the splenic nerve. The nerve filament was placed on electrodes to record efferent activity before and after administration of argininelysine mixture solution, glucose or ATP solution. Enhancement of efferent activity of vagal thymic nerve was observed after i.v. administration of arginine-lysine mixture, glucose and ATP solution. Suppression in efferent activity of splenic nerve was investigated following i.v. administration of arginine-lysine mixture, glucose and ATP solution. These results suggest that i.v. arginine-lysine, glucose and ATP increase thymic lymphocyte release, and that i.v. arginine-lysine, glucose and ATP enhance NK cell activity.

Adenosine Monophosphate↗