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H Demirel

Publications and source records attributed to H Demirel.

11 recordsLinked to original sources
PubMed2004

Iron, nitric oxide, and myeloperoxidase in asthmatic patients.

Plasma nitric oxide (NO), myeloperoxidase (MPO), and iron (Fe) levels were determined in bronchial asthma. The relations among these parameters in different stages of asthma were interpreted. Their association with airway inflammation observed in patients with bronchial asthma as well as the roles and the contributions to the pathological processes were evaluated. A total of 62 individuals, 32 asthmatics and 30 controls, were included into the scope of this study. Plasma nitric oxide metabolites (NOx) and MPO and Fe levels were determined by the Griess reaction, ELISA, and the automated TPTZ (2,4,6-tri[2-pyridyl]-5-triazine) method, respectively. In the asthmatic individuals, plasma NOx, MPO, and Fe concentrations were 133 +/- 13 microM, 95 +/- 20 ng/ml, and 159 +/- 20 microg/dl, respectively; in the control group these values were 82 +/- 11 microM, 62 +/- 11 ng/ml, and 96 +/- 9 microg/dl. Increased values were detected for plasma MPO (p > 0.05), NOx (p < 0.01), and Fe (p < 0.01) concentrations in asthmatic individuals. Considering the facts that NO modulates the catalytic activity of MPO and induces the expression of heme oxygenase as important contributors to the mechanisms causing free Fe release, it is concluded that elevated NOx, MPO, and Fe levels observed in the asthmatic group act in a concerted manner and appear to be involved in the pathogenesis of asthma.

Adult↗
PubMed2003

A case with Pyle type metaphyseal dysplasia: clinical, radiological and histological evaluation.

Pyle type metaphyseal dysplasia is a rare autosomal recessive disease that is primarily affect metaphyses. Here we present a case with Pyle type metaphyseal dysplasia. The characteristic features of the case were metapyhseal broadening with undertubulation and Erlenmeyer flask sign at distal femoral and proximal tibial metaphyses. There were also platyspondyly with biconcave lens appearance of the vertebral bodies, congenital hip dislocation and normal cranium. Bone histopathology showed decreased number of osteoclasts. To the best of our knowledge, this is the first reported case of Pyle type metaphyseal dysplasia from Turkey.

Abnormalities, Multiple↗
PubMed2000

Glucocorticoid-induced alterations in the rate of diaphragmatic fatigue.

These experiments tested the hypothesis that in vitro diaphragmatic fatigue resistance is enhanced in animals treated with glucocorticoids. Female Sprague-Dawley rats (4 months old) were randomly assigned to a control (N =12) or glucocorticoid treatment group (N =12). Treatment animals were injected daily for 8 days with prednisolone (5 mg kg(-1)); control animals were injected with the same volume of the vehicle. Twenty-four hours after the last injection, the following in vitro diaphragmatic contractile properties were examined in costal diaphragm strips: maximal twitch (P(t)) half time to peak tension (1/2 TPT), half relaxation time (1/2 RT), force-frequency relationship, and the rate of fatigue development. Diaphragmatic fatigue was assessed by monitoring the decrease in force production (measured as percent of initial force) over a 60-min contractile period. The in vitro fatigue protocol incorporated a supramaximal stimulus delivered at 30 Hz every 2 s with a train duration of 250 ms (duty cycle 12.5%). Citrate synthase (CS), superoxide dismutase (SOD), and water content of the costal diaphragm were also determined. Glucocorticoid administration induced an 18.9% (P<0.05) decrease in animal body weight when compared to the control. Similar weight losses also occurred in the diaphragm with a decrease (P<0.05) in mass of 16.5% compared to the control. Furthermore, prednisolone treatment resulted in a significant reduction in the cross-sectional area (CSA) of type IIb fibres with no change in the CSA area of type I and IIa fibres. 1/2 TPT and 1/2 RT were significantly prolonged (P<0.05) in the glucocorticoid treated rats whereas the force-frequency curve was unaltered (P>0.05). Fatigue resistance was greater in the glucocorticoid group (P<0.05); the relative force production differed between groups at the end of 1 min of contractions and remained different throughout the 60-min fatigue protocol. Citrate synthase, SOD, and water content were not different between groups. These experiments support the hypothesis that costal diaphragm strips of glucocorticoid-treated rats possess a greater resistance to fatigue. We postulate that this fatigue resistance is due to glucocorticoid-induced changes muscle fibre type composition.

Animals↗
PubMed1999

Methemoglobinemia as an uncommon cause of cyanosis.

Cyanosis is usually caused by decreased arterial oxygen saturation due to pulmonary or cardiac diseases. Methemoglobinemia is a rare cause, sometimes with lethal outcome. Two patients are described, both with an unremarkable cardiopulmonary history, presented with severe cyanosis due to aniline-induced methemoglobinemia that developed at work. The symptoms and the treatment of methemoglobinemia are discussed.

Adult↗
PubMed1999

Obesity is associated with increased myocardial oxidative stress.

OBJECTIVE: To determine: 1) whether obesity predisposes the myocardium to oxidative stress as evidenced by higher tissue levels of myocardial lipid peroxidation, and 2) what cellular mechanisms are responsible for this predisposition. DESIGN: Comparative, descriptive study of the myocardial tissue of lean and obese Fatty Zucker animals. ANIMALS: 12 month old lean (-/fa; n = 6; mean body weight = 590 g) and obese (fa/fa; na = 7; mean body weight= 882 g) male Fatty Zucker rats. MEASUREMENTS: Basal lipid peroxidation (assessed using thiobarbituric reactive acid substances (TBARS) and cumene hydroperoxide equivalents), oxidative and antioxidant enzyme activities (citrate synthase (CS), superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT), thiol content, heat shock protein expression (HSP72/73) and TBARS concentrations following an iron-mediated challenge in vitro. RESULTS: Compared to lean, lipid peroxidation was greater (P < 0.05) in the left ventricle (LV) from obese rats as indicated by higher levels of lipid hydroperoxides (mean = 11.48 vs 13.7 cumene hydroperoxide equivalents (CHPE)/mg lipid) and TBARS (mean = 11.1 vs 13.9 nMol/mg lipid.). The activity of the manganese isoform of superoxide dismutase in the LV was higher (P < 0.05) in obese animals, compared to controls (mean = 135 vs 117 U/mg protein). In contrast, LV catalase and glutathione peroxidase activities did not differ (P > 0.05) between groups. Also, LV levels of HSP 72 (inducible) and 73 (constitutive) did not differ (P > 0.05)( between lean and obese animals. Following an iron-stimulated oxidative challenge in vitro, TBARS concentration was significantly greater (P < 0.05) in LV of obese rats compared to the lean (mean = 12.7 vs 16.7 nMol/mg lipid). CONCLUSIONS: These results support the notion that obesity predisposes the myocardium to oxidative stress. However, the postulate that obesity is associated with elevated myocardial antioxidant enzyme activities and HSPs was only partially supported by these findings.

Animals↗
PubMed1999

Endurance training reduces the rate of diaphragm fatigue in vitro.

PURPOSE: The present study examined the effects of endurance training on the contractile and biochemical properties of the rat costal diaphragm in vitro. METHODS: Sixty-four rats were divided into two groups: exercise trained (T) and control (C). Training consisted of treadmill running 5 d x wk(-1), 60 min x d(-1) at approximately 70% of VO2max, over a 10-wk period. RESULTS: Control diaphragm strips produced an average of 12% less force from minute 15 to 50 of a 60-min in vitro fatigue protocol, compared with the T diaphragm strips (P < 0.01). T diaphragms had 10.1% higher citrate synthase (CS) and 12.1% higher superoxide dismutase (SOD) activities compared with the C (P < 0.05). Despite a significant decrease (P < 0.05) in Type IIb myosin heavy chains (MHC) and an increase (P < 0.05) in Type I MHC in T diaphragms, maximal shortening velocity (Vmax) in the diaphragm was not different between T and C animals. No differences were observed in specific force or the relative proportions of myosin light chains between groups. CONCLUSIONS: These findings suggest that endurance training reduces the rate of diaphragm fatigue in vitro but has no effect on Vmax or specific force.

Animals↗
PubMed1997

Exercise training-induced changes in respiratory muscles.

Interest in the adaptive strategies of respiratory muscles in response to exercise training has grown in recent years. Animal studies have clearly demonstrated that regular endurance exercise training results in small but significant increases in oxidative and antioxidant enzyme activities in both inspiratory and expiratory muscles. Further, exercise training has been shown to promote a shift in the fast myosin heavy chain isoforms (e.g. from type IIb to IId) within the costal diaphragm of endurance-trained rodents. Human studies using numerous respiratory muscle training programmes have shown that respiratory muscle training results in an increased work capacity of the ventilatory musculature. However, the issue of whatever respiratory muscle training improves whole body endurance capacity remains controversial. Although some authors have reported that ventilatory muscle training results in improved whole body exercise, many investigators argue that respiratory muscle performance does not limit high intensity exercise tolerance or influence maximum oxygen table uptake (VO2max). The explanation for the divergent findings is unclear but may be due to variance in the exercise tasks used to evaluate exercise endurance. This is an interesting area for future research.

Adaptation, Physiological↗
PubMed1996

Age-related increases in diaphragmatic maximal shortening velocity.

Recent evidence demonstrates that aging results in an increase in fast (type IIB) myosin heavy chain (MHC) in the rat diaphragm. It is unknown whether this age-related change in fast MHC influences the diaphragmatic maximal shortening velocity (Vmax). Therefore, we tested the hypothesis that aging is associated with an increase in the diaphragmatic Vmax and that the increase in the Vmax is highly correlated with the percentage of type IIb MHC. In vitro contractile properties were measured with costal diaphragm strips obtained from young (4 mo old; n = 8) and (old 24 mo old; n = 8) male Fischer-344 rats. Diaphragmatic maximal tetanic specific force production was 14.5% lower in the old compared with the young animals (23.0 +/- 0.4 vs. 19.7 +/- 0.8 N/cm2; P < 0.05). In contrast, the diaphragmatic Vmax was significantly higher in the old compared with the young animals (5.5 +/- 0.1 vs. 4.4 +/- 0.3 lengths/s; P < 0.05). Although the percent type IIb MHC was significantly higher (approximately +14%; P < 0.05) in the old compared with the young animals, the correlation between Vmax and percent type IIb MHC was relatively low (r = 0.50; P > 0.05). These data support the hypothesis that an age-related increase in diaphragmatic Vmax occurs; however, factors in addition to type IIb MHC are involved in regulating diaphragmatic Vmax. Interestingly, although aging resulted in a decrease in diaphragmatic maximal specific force production, power output at all muscle loads was maintained in the old animals due to the increase in diaphragmatic shortening velocity.

Aging↗
PubMed1996

Effects of aging and obesity on respiratory muscle phenotype in Zucker rats.

Because obesity results in an increased work of breathing, we tested the hypothesis that the oxidative properties and myosin heavy chain (MHC) isoform profiles in respiratory muscles would differ between lean and obese animals. Furthermore, we postulated that obesity-related changes in respiratory muscles would be independent of age. To test these hypothesis, samples of the costal diaphragm, crural diaphragm, and parasternal intercostal muscles were removed from three age groups (young, adult, and old) of obese and lean Zucker rats. Citrate synthase (CS) activity was measured as a marker of oxidative capacity, and MHC isoforms were identified with gel electrophoresis. Analysis revealed that CS activity was significantly higher in the crural and costal diaphragms and parasternal intercostal of obese animals compared with lean animals (P < 0.05); this obesity-related increased in CS activity was related independent of age. Furthermore, respiratory muscle percent type IIb MHC was lower and percent type I MHC isoforms were higher in obese animals compared with lean animals. These data support the notion that obesity results in a fast-to-slow shift in MHC phenotype and an increase in oxidative capacity in major inspiratory muscles. The shift in MHC isoforms in obese animals is also age related, whereas the obesity-mediated increase in oxidative capacity is relatively independent of age.

Aging↗
PubMedDate not supplied

Protection of intestinal anastomoses in septic environment with peritoneal graft and polyglycolic acid mesh: an experimental study.

We carried out an experimental study in dogs to evaluate the outcome of large bowel anastomosis with 6 stitches (Group C, n : 6) in a septic environment with protection by a polyglycolic acid (PGA) mesh (Group M, n : 12) or peritoneal graft (Group P, n : 12). Thirty dogs were used to compare the techniques. Two dogs in each group were re-operated after 3, 5, 7, 14, 28 and 90 days. They were evaluated for adhesion formation, lumen diameter (anastomotic index), clinical features, histologic appearance and quality of healing at the anastomotic sites. All dogs in group P and group M survived, whereas 2 dogs in the control group died of anastomotic leakage and 3 dogs were re-operated for anastomotic leakage and peritonitis. In group M, one dog was reoperated because of the anastomotic leakage and two dogs were reoperated because of the anastomotic stenosis. Also, 4 anastomoses showed evidence of moderate stenosis. In group P, three anastomoses were graded as minimal stenosis. Histopathologic evaluation showed more complete epithelization, less inflammation, and less adhesion in group P than group M. We could not find any study in the literature that described and compared both techniques. We report here the results of such a study.

Anastomosis, Surgical↗