Biomedical subjects

Zeynep Alkan

Publications and source records attributed to Zeynep Alkan.

6 recordsLinked to original sources

PubMed2006

The potentiating and protective effects of ascorbate on oxidative stress depend upon the concentration of dietary iron fed C3H mice.

Ascorbic acid (AA) is an antioxidant that, in the presence of iron and hydrogen peroxide, increases the production of hydroxyl radicals in vitro. Whether AA has similar pro-oxidant properties in vivo may depend upon the relative balance of iron and AA concentrations. In this study, C3H mice were fed diets supplemented with 100 or 300 mg/kg iron, with or without AA (15 g/kg), for 12 months. Liver AA concentrations were greater in mice fed AA-supplemented diets with either low or high iron (P=.0001), while the high-iron diet was associated with a significantly lower liver AA concentration regardless of AA supplementation (P=.0001). Only mice fed the high-iron diet with AA had a significantly greater liver iron concentration (P=.05). In the high-iron group, AA reduced oxidative stress, as measured by greater activities of glutathione peroxidase, superoxide dismutase (SOD) and catalase and by significantly lower concentrations of 4-hydroxylalkenal (HAE) and malondialdehyde (MDA). In mice fed the low-iron diet, AA was associated with greater concentrations of HAE and MDA and with lower activities of SOD. However, AA did not increase the concentrations of modified DNA bases with the low-iron diet but was associated with significantly lower concentrations of modified DNA bases in mice fed the high-iron diet. In conclusion, dietary AA appears to have mild pro-oxidant properties at low-iron concentrations but has a strong antioxidant effect against oxidative stress and DNA damage induced by dietary iron in mouse liver.

Aldehydes↗

PubMed2005

Cricopharyngeal muscle electromyography in laryngopharyngeal reflux.

OBJECTIVES/HYPOTHESIS: The objective was to determine whether laryngopharyngeal reflux was associated with an electrophysiological abnormality of the main part of the upper esophageal sphincter, namely, the cricopharyngeal muscle, which could be related to laryngopharyngeal reflux symptoms. STUDY DESIGN: A prospective study of 20 patients with symptoms of laryngopharyngeal reflux. METHODS: The diagnosis was based on clinical, laryngoscopic, and ambulatory 24-hour pH monitoring findings. Double-probe pH monitoring was performed with placement of the distal and proximal probes 5 cm above the proximal border of the lower esophageal sphincter and 15 cm proximal to the distal probe, in or just beneath the upper esophageal sphincter. Electromyographic recordings were obtained simultaneously on submental and cricopharyngeal muscles during water swallowing. The peak of the submental electromyographic amplitude and its duration was measured using bipolar surface electrodes placed under the chin. The electromyographic features of the cricopharyngeal muscle were investigated by means of concentric needle electrodes inserted percutaneously both in 20 normal subjects and in 20 patients with laryngopharyngeal reflux. RESULTS: All electrophysiological parameters were normal in all of the patients. The durations of foreburst revealed significant correlation with the number of reflux episodes and acid exposure time (P = .026 and P = .044, respectively). CONCLUSION: The duration of the foreburst correlating with acid exposure time and number of reflux episodes suggested that foreburst duration was extended because of the irritation caused by the acid reflux.

Adult↗

PubMed2004

Plasma selenium decrease during pregnancy is associated with glucose intolerance.

There is an increased requirement for selenium during pregnancy, presumably for fetal growth, which manifests as decreasing maternal blood and tissue selenium concentrations. These decreases are greater in pregnant women with gestational or preexisting diabetes. We measured selenium status and glucose tolerance between wk 12 and 34 of gestation in 22 pregnant women. We found that the increase in blood glucose in response to an oral glucose challenge at 12 wk gestation and the increase in fasting glucose during pregnancy were inversely correlated with plasma selenium concentration. Women with lower plasma glutathione peroxidase activities during pregnancy also tended to have higher fasting glucose levels. These inverse relationships between selenium status and glucose tolerance are consistent with earlier observations that suggest a link between selenium and glucose metabolism. The observation that changes in serum glucose were not accompanied by changes in insulin suggests that selenium may affect glucose metabolism downstream from insulin, or through independent energy regulatory pathways such as thyroid hormone.

Adult↗

PubMed2004

A case of pneumocephalus and meningitis as a complication of silent otitis media.

Silent otitis media is a progressive otogenic disease. Intracranial manifestations of this complication are limited; the most common is meningitis. We report a case of meningitis and pneumocephalus as a complication of silent otitis media. To the best of our knowledge, this is the first reported case of pneumocephalus as a complication of silent otitis media.

Aged↗

PubMed2004

[Grand mal seizure following intrathecal fluorescein use].

In a 43-year-old woman, 1 ml of 5% fluorescein diluted with 10 ml of cerebrospinal fluid (CSF) was injected into the subarachnoid space at the L4-L5 level to evaluate nasal CSF leakage. After the injection, amnesia and grand mal seizure developed following a low-back pain spreading through the right leg. The patient was treated with antiedematous and anticonvulsant drugs. CSF drainage and vigorous hydration were performed. The patient recovered without sequelae. It was concluded that intrathecal fluorescein should be used with caution.

Adult↗

PubMed2003

[The topographical anatomy of the external branch of the superior laryngeal nerve and its importance in thyroid surgery: a cadaver study].

OBJECTIVES: We investigated topographical anatomic features of the external branch of the superior laryngeal nerve (SLN) in relation to the superior thyroid artery (STA) and its vulnerability to injury in individuals with a normal thyroid size. STUDY DESIGN: Thirty fresh cadavers (18 females, 12 males; age range 20 to 50 years) with a normal thyroid size and no signs of abnormality in the neck were studied. The external branch of the SLN was identified and classified according to the system proposed by Cernea et al. RESULTS: The topographical relationship between the external branch of the SLN, the STA, and the upper pole of the thyroid gland was identified in 54 thyroid lobes (90%). Identification was not possible in six lobes because of bleeding or injury. The location of the external branch of the SLN was consistent with type 1 in 28 lobes (51.8%) and type 2 in 26 lobes (48.2%; type 2a in 37.1% and type 2b in 11.1%). No significant relationships existed between the type of the nerve, gender, and age, nor was there any symmetry with regard to the location of the external branch of the SLN in the same subject. CONCLUSION: Nearly half of the Turkish population with a normal thyroid gland size present high surgical risks during thyroid surgery because of the course of the external branch of the SLN.

Adult↗