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Biomedical subjects

Igor A Harsch

Publications and source records attributed to Igor A Harsch.

11 recordsLinked to original sources
PubMed2003

Impaired gastric ulcer healing in diabetic rats: role of heat shock protein, growth factors, prostaglandins and proinflammatory cytokines.

Gastric mucosa of diabetic rats is highly vulnerable to acute injury, but little is known about the influence of diabetic conditions on the healing of gastric ulcers. In this study, streptozotocin (70 mg/kg injected intraperitoneally) was used to induce diabetes mellitus in rats. Four weeks after streptozotocin injection, gastric ulcers were induced using the acetic acid method, and 10 days later, the healing rate and the gastric blood flow (GBF) were measured by planimetry and hydrogen (H(2))-gas clearance method, respectively. Six major groups of rats with gastric ulcers were used: (1) vehicle (saline); (2) streptozotocin alone; (3) insulin (4 IU/day intraperitoneally); (4) streptozotocin plus insulin; (5) pentoxifylline, an inhibitor of synthesis and release of tumor necrosis factor-alpha (TNF alpha); and (6) aspirin, a non-selective inhibitor of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), and rofecoxib, the highly selective COX-2. In the diabetic rats, a significant delay in ulcer healing ( approximately by 300%), accompanied by a decrease in the gastric mucosal blood flow was observed. The prolongation of the healing in diabetic animals was associated with an increase in gastric mucosal expression and release of TNFalpha, interleukin-1 beta (IL-1 beta), suppression of the vascular endothelial growth factor (VEGF), platelet endothelial cell adhesion molecule-1 (PECAM-1) and the mucosal overexpression of heat shock protein 70 (HSP 70). Administration of insulin reversed the delay in ulcer healing and significantly decreased the expression of IL-1 beta and TNF-alpha, while producing the rise in the expression of VEGF and PECAM. Pentoxifylline, an inhibitor of TNF-alpha, which by itself accelerated ulcer healing in non-diabetic rats, counteracted the increase in the area of gastric ulcer induced by streptozotocin, raised significantly gastric blood flow and suppressed the plasma TNF-alpha levels. Aspirin and rofecoxib, that significantly suppressed the mucosal prostaglandin E(2) generation in ulcer area, delayed significantly the rate of ulcer healing and decreased the GBF at ulcer margin in non-diabetic rats, and these changes were significantly augmented in diabetic animals. We conclude that: (1) Experimental diabetes dramatically impairs ulcer healing, depending upon the increased release of proinflammatory cytokines and the attenuation of angiogenesis that can limit the ulcer healing effects of locally produced HSP 70 and TNF-alpha. (2) Insulin reversed this impairment of ulcer healing in diabetic rats, mainly due to the enhancement of angiogenesis and reduction in expression of cytokines in the ulcer area. (3) Classic non-steroidal anti-inflammatory drugs such as aspirin prolonged ulcer healing under diabetic conditions due to suppression of endogenous prostaglandins and the fall in the microcirculation at the ulcer margin and these effects were mimicked by selective, so called "safe" COX-2 inhibitor, rofecoxib, suggesting that both COX isoforms are important sources of prostaglandins that are essential in the ulcer healing in diabetes.

Animals↗
PubMed2003

Continuous positive airway pressure treatment rapidly improves insulin sensitivity in patients with obstructive sleep apnea syndrome.

The obstructive sleep apnea syndrome is typically associated with conditions known to increase insulin resistance as hypertension, obesity, and diabetes. We investigated whether obstructive sleep apnea itself is an independent risk factor for increased insulin resistance and whether continuous positive airway pressure (CPAP) treatment improves insulin sensitivity. Forty patients (apnea-hypopnea index > 20) were treated with CPAP. Before, 2 days after, and after 3 months of effective CPAP treatment, hyperinsulinemic euglycemic clamp studies were performed. Insulin sensitivity significantly increased after 2 days (5.75 +/- 4.20 baseline versus 6.79 +/- 4.91 micromol/kg.min; p = 0.003) and remained stable after 3 months of treatment. The improvement in insulin sensitivity after 2 days was much greater in patients with a body mass index less than 30 kg/m2 than in more obese patients. The improved insulin sensitivity after 2 nights of treatment may reflect a decreasing sympathetic activity, indicating that sleep apnea is an independent risk factor for increased insulin resistance. The effect of CPAP on insulin sensitivity is smaller in obese patients than in nonobese patients, suggesting that in obese individuals insulin sensitivity is mainly determined by obesity and, to a smaller extent, by sleep apnea.

Body Mass Index↗
PubMed2003

Immunoglobulin E production in chronic pancreatitis.

OBJECTIVES: Serum immunoglobulin E (IgE) was investigated in patients with chronic pancreatitis in order to elucidate possible disease mechanisms linking pancreatitis, adverse reaction to foods and allergy. DESIGN AND METHODS: Serum IgE was analysed in 86 non-atopic patients with advanced chronic pancreatitis and 54 non-atopic controls. IgE detection was performed by enzyme-linked immunofluorescence. RESULTS: Mean IgE levels (+/- standard error of mean) in chronic pancreatitis patients (286.1+/-49 kU/l) were found to be significantly elevated compared to controls (67.7+/-11 kU/l; P<0.0001). Normal IgE levels (<100 kU/l) were present in 40/54 control patients (74.1%), but only 39/86 pancreatitis patients (45.3%). Of the patients with chronic pancreatitis, 47/86 (54.6%) had clearly elevated IgE levels of >100 kU/l and their IgE values did not show a Gaussian distribution. However, nine-fold higher IgE levels were found in chronic pancreatitis patients with alcohol consumption of >25 g/day and exocrine insufficiency (915.5+/-240 kU/l) than in pancreatitis patients with normal exocrine function and no alcohol consumption (103.4+/-43 kU/l; P<0.001). Moreover, acute episodes of chronic pancreatitis were found to increase serum IgE levels. CONCLUSIONS: In patients with chronic pancreatitis, serum IgE production is markedly enhanced, especially during acute inflammatory episodes or when alcohol is consumed. Since abstinence from alcohol and pancreatic enzyme substitution are associated with clearly lower IgE levels, it may be concluded that pancreatic insufficiency with reduced nutrient digestion and alcohol consumption stimulate IgE production. This finding gives rise to the speculation that, apart from pancreatic inflammation, cross-linking of IgE with alimentary or other antigens might be involved in the pathophysiology of a sub-population of patients with chronic pancreatitis and manifest pancreatic insufficiency.

Adult↗
PubMed2002

Effect of Helicobacter pylori on delay in ulcer healing induced by aspirin in rats.

Helicobacter pylori and nonsteroidal anti-inflammatory drugs (NSAIDs) are major pathogenic factors in peptic ulcer disease but whether these two factors exert synergistic or antagonistic effects on ulcer healing has been a subject of controversy. We compared the effect of aspirin alone with that of aspirin combined with H. pylori on gastric acid secretion and healing of acetic acid gastric ulcers in rats. The H. pylori colonization of gastric mucosa was determined by viable H. pylori culture, histology and assessment of bacterial DNA using polymerase chain reaction (PCR). The area of ulcers, gastric blood flow, mucosal generation of prostaglandin E(2) and plasma gastrin levels and expression of cyclooxygenase-1, cyclooxygenase-2 and growth factors was determined. Aspirin delayed significantly the healing of chronic gastric ulcers, decreased the gastric blood flow at the ulcer margin and gastric mucosal prostaglandin E(2) generation being without significant influence on gastric acid output. H. pylori acquisition that produced moderate gastric inflammation at the ulcer margin delayed significantly the healing of gastric ulcers, decreased significantly both the gastric blood flow at the ulcer margin and the gastric secretion while raising significantly the gastric mucosal prostaglandin E(2) generation and plasma gastrin levels. H. pylori infection attenuated the aspirin-induced inhibition of ulcer healing and accompanying fall in the gastric blood flow. Both aspirin and H. pylori up-regulated significantly cyclooxygenase-2 messenger RNA (mRNA) and protein but not that of cyclooxygenase-1 at the ulcer margin. Aspirin reduced significantly the transforming growth factor alpha- and vascular endothelial growth factor mRNAs, but these effects were significantly attenuated by H. pylori. We conclude that H. pylori antagonizes, in part, aspirin-induced delay of ulcer healing due to suppression of acid secretion, the enhancement in prostaglandin E(2) possibly derived from cyclooxygenase-2 and the overexpression of transforming growth factor alpha and vascular endothelial growth factor in the ulcer area.

Animals↗
PubMed2002

Auto-CPAP therapy for obstructive sleep apnea: induction of microarousals by automatic variations of CPAP pressure?

STUDY OBJECTIVES: To investigate the frequency of microarousals (MA) associated with pressure changes during auto-CPAP therapy (APAP) for obstructive sleep apnea (OSA). DESIGN: Patients with OSA were studied by polysomnography during APAP therapy (Somnosmart). The MA were classified on the basis of concomitant changes in APAP pressure. SETTING: Sleep laboratory of a university hospital PARTICIPANTS: 30 patients with moderate to severe OSA. MEASUREMENTS AND RESULTS: The mean AHI during APAP was 4.7+/-4.7, the mean arousal index was 14.5+/-6.6 per hour. During epochs with a pressure variation greater than 0.5 mbar, significantly more MA occurred (0.30+/-0.17 MA per epoch) than in epochs with constant treatment pressure (0.10+/-0.054 MA per epoch; p<0.001). There were more MA during pressure-increase epochs than during pressure-decrease epochs (0.42+/-0.24 vs. 0.16+/-0.12 MA per epoch; p<0.001). 82.5 percent of the MA were not preceded by a significant change in pressure (at least 0.5 mbar within 30 sec.), 10.6% were associated with a significant prior increase and 6.9% with a significant prior decrease in pressure. The percentage of MA preceded by a significant pressure variation varied between 2.3% and 61%, with a mean of 18.9%. CONCLUSIONS: The overall frequency of MA was low, and in most individuals the relative amount of "pressure-associated MA" was not significant. However in some individuals it cannot be excluded that some additional MA may have been induced by pressure variations. Should it prove possible to prevent such "pressure-associated MA" by optimizing the regulation of APAP pressure, the overall clinical effect of APAP treatment may be improved.

Adult↗
PubMed2002

Insulin resistance, hyperleptinemia, and obstructive sleep apnea in Launois-Bensaude syndrome.

OBJECTIVE: Launois-Bensaude Syndrome (LBS) is a very rare cause of obesity, characterized by a symmetrical accumulation of a very large number of lipomata in different regions of the body, excluding the face, the forearms, and the shanks. Obesity is known to be closely associated with insulin resistance, hyperleptinemia, and obstructive sleep apnea (OSA). We were interested in studying whether these conditions are also present in patients with obesity due to LBS with a similar frequency as in patients with "simple" truncal obesity. RESEARCH METHODS AND PROCEDURES: We performed polysomnography and hyperinsulinemic euglycemic clamp studies and measured serum leptin in three patients with LBS and in six patients with "simple" truncal obesity, matched for sex and body mass index (LBS group, 36.39 kg/m(2); controls, 35.82 kg/m(2)). RESULTS: Polysomnography revealed severe OSA in one LBS patient with marked "horsecollar lipomata." In the other LBS patients, no OSA could be demonstrated. The leptin levels of the two groups were comparable (LBS group, 36.39 microg/liter; controls, 37.18 microg/liter) and the insulin responsiveness index was also comparable in the two groups (LBS group, 3.47 micromol/kg. minute; controls, 3.79 micromol/kg. minute). DISCUSSION: Patients with LBS demonstrated similar metabolic features in terms of insulin sensitivity and hyperleptinemia as patients with "simple" truncal obesity. LBS is not strictly associated with OSA.

Adult↗