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Biomedical subjects

Mehmet Turgut

Publications and source records attributed to Mehmet Turgut.

At least 19 recordsLinked to original sources
PubMed2006

Effects of formaldehyde exposure on granule cell number and volume of dentate gyrus: a histopathological and stereological study.

The hippocampal formation is a complex region of the brain related to memory and learning. The purpose of the present study was to determine whether exposure of neonatal rats to formaldehyde (FA) had either early or delayed effects on the numbers of granule cells in the dentate gyrus (DG). After birth, the neonatal male Wistar rats were exposed throughout a 30-day period to various concentrations of FA: 0 (control group), 6 ppm (low concentration group) and 12 ppm (high concentration group). This was done by placing them for 6 h/day and 5 days per week in a glass chamber containing FA vapor. Then, five animals from each group were anesthetized and decapitated on postnatal day (PND) 30, and the remaining five animals were sacrificed on PND 90 by intracardiac perfusion using 10% neutral buffered FA solution. The Cavalieri principle of stereological approaches was used to determine the volume of the DG in these sections. The optical fractionator counting method was used to estimate the total number of granule cells in the DG. The appearance of granule cells was normal under light microscopy in all PND 30 and PND 90 groups. There were significant age-related reductions in the volume of the DG at PND 90 irrespective of which group was examined. Significant age-related neuron loss was also determined at PND 90 compared to that at PND 30. Rats treated with a high concentration FA were found to have fewer granule cells than either the animals treated with a low concentration FA or the control group (p<0.01 and p<0.01, respectively) at PND 90 but not at PND 30. These findings clearly indicate that granule cells in the DG may be vulnerable to stress and the concentration of FA to which they are exposed during early postnatal life, and also that a neurotoxic effect of high dose FA on cell number is only seen after a long time period. These results may explain why some disorders do not appear until later life.

Age Factors↗
PubMed2006

Immunohistochemical profile of transforming growth factor-beta1 and basic fibroblast growth factor in sciatic nerve anastomosis following pinealectomy and exogenous melatonin administration in rats.

Collagen scar formation at the cut end of a peripheral nerve, an important problem in clinical practice for neurosurgeons, obstructs sprouting of axons into appropriate distal fascicles, and thereby limits the regeneration process. Researchers have attempted to control collagen accumulation and neuroma formation with various physical and chemical methods, but with limited functional success. Recently, it has been demonstrated that transforming growth factor (TGF)-beta and basic fibroblast growth factor (bFGF) play an important role in collagen production by fibroblasts and in Schwann cell activity. In our study, rats were divided into a control group, a melatonin-treated group, a surgical pinealectomy group, and a group treated with melatonin following pinealectomy. They then underwent a surgical sciatic nerve transection and primary suture anastomosis. At 2 months after anastomosis, the animals were sacrificed and unilateral sciatic nerve specimens, including the anastomotic region, were removed and processed for immunohistochemical study from two animals in each group. For each antibody, immunoreactivity was assessed using a semiquantitative scoring system. Strong TGF-beta1 and/or bFGF expression was observed in the epineurium of animals that underwent pinealectomy, but no or weak staining was observed in animals in the control and melatonin treatment groups. Based on these data, we suggest that both TGF-beta1 and bFGF have important roles in control of collagen accumulation and neuroma formation at the anastomotic site, and that the pineal neurohormone melatonin has a beneficial effect on nerve regeneration.

Animals↗
PubMed2006

The effect of exogenous melatonin administration on trabecular width, ligament thickness and TGF-beta(1) expression in degenerated intervertebral disk tissue in the rat.

Intervertebral disk (IVD) degeneration, a complex pathological condition of varying origins, causes low back pain. Degenerative changes in IVD tissue affect the adjacent vertebral structure, resulting in a decreased vertebral trabecular width. It has been suggested that transforming growth factor-beta 1 (TGF-beta(1)) may have a role in the repair of connective tissue, as it occurs in the IVD degeneration process. In this study, we investigated the effects of exogenous melatonin (MEL) administration on vertebral trabecular width, ligament thickness and TGF-beta(1) expression in degenerated IVD tissue. Fifteen adult male Swiss Albino rats were divided randomly into three groups; nonoperated control, operated degeneration, and MEL treatment groups. In the operated degeneration and MEL treatment groups, cuts were made parallel to the end plates in the posterior annulus fibrosus at the fifth and tenth vertebral segments of the tail to induce IVD degeneration. In each group, TGF-beta(1) immunoreactivity and morphometry of vertebral trabecular width and anterior and posterior ligament thickness were evaluated. Histologically, disorganisation and irregularity of collagen fibres was seen in the degenerated (operated) IVD. Increased TGF-beta(1) expression in multinuclear chondrocytes was also observed as was decreased vertebral trabecular width. Importantly, the reduction of trabecular width observed in the operated degenerated group was reversed after MEL administration (p<0.0001). Similarly, TGF-beta(1) expression in multinuclear chondrocytes was dramatically increased after exogenous MEL application. Thus, there was a regression in histopathological changes after MEL treatment, with disk appearances similar to those of the control group. Based on our findings, we suggest that MEL activates the recovery process in the degenerated IVD tissue, possibly by stimulating TGF-beta(1) activity. This is the first report investigating the involvement of the pineal hormone MEL in the repair of rat IVD.

Animals↗
PubMed2006

Correlation of serum trace elements and melatonin levels to radiological, biochemical, and histological assessment of degeneration in patients with intervertebral disc herniation.

The aim of our study was to assess the blood concentrations of some trace elements and melatonin (MLT) in patients with intervertebral disc herniation (IDH) and to investigate the interaction of histological and biochemical degeneration findings with aging. The present study was carried out on 13 subjects (8 women and 5 men) diagnosed with IDH. They were divided into three groups according to their ages. Nighttime serum MLT, zinc (Zn), and magnesium (Mg) levels were determined in all patients. In addition, computed tomography (CT) scan of the brain and magnetic resonance imaging examination of the lumbar spine were obtained in this study. The Zn level and Zn/Mg ratio showed a decline in patients with IDH with aging, whereas the serum Mg level and tissue hydroxyproline content increased. A positive correlation between serum Zn and MLT concentrations was found (r=0.104, p=0.734). In addition, there was a positive correlation between serum Zn level and Zn/Mg ratio (r=0.835 and p<0.01), and a negative correlation between serum Mg level and Zn/Mg ratio (r=-0.571, p<0.05). On CT study, both volume percentage of calcified pineal gland and density of calcification were found to increase progressively with advancing age. The results of semiquantitative evaluation of disc tissues of patients with IDH for histological degeneration findings showed that 66.7% of discs treated had slight degeneration in younger age group, but 75.0% and 100% of discs had moderate or marked degeneration in older age groups. Our data indicated that there is a close relationship between MLT and Zn or Mg levels in the serum samples of patients with IDH, and the levels of these elements might be affected by the presence of degeneration process and serum MLT level, or vice versa.

Adult↗
PubMed2006

Effects of ovariectomy and tamoxifen on rat bone tissue: histomorphometric and histopathologic study.

OBJECTIVE: To investigate possible detrimental effects on bone tissue induced by ovariectomy and tamoxifen (TMX) using bone densitometry and histomorphologic analysis. STUDY DESIGN: Twenty-four rats were allocated into 4 groups: group 1, intact normal rats (n = 6); group 2, ovariectomized rats (n = 6); group 3, normal female rats that received 1 mg/kg/day TMX dissolved in dimethyl sulfoxide (DMSO) for 2 months (n = 6); group 4, normal female rats that received DMSO for the same duration and with a volume equal to that of TMX (n = 6). Results of histomorphometric analysis for trabecular thickness, number of osteoblasts and osteoclasts, trabecular number, and area and cortical thickness were compared. RESULTS: No significant effects of ovariectomy on femoral or lumbar bone mineral density (BMD) were found. In the TMX group, the value of femoral BMD increased significantly compared to control group cellular and pathologic changes. TMX caused significant decrease in osteoblasts compared to the control group. CONCLUSION: TMX has a positive effect on inorganic bone tissue, but a negative effect on number of osteoblasts and osteoclasts. Future studies investigating estrogenic and antiestrogenic effects of TMX should include cellular parameters related to proliferation using histopathologic and histomorphometric analyses.

Animals↗
PubMed2005

Pinealectomy stimulates and exogenous melatonin inhibits harmful effects of epileptiform activity during pregnancy in the hippocampus of newborn rats: an immunohistochemical study.

OBJECTIVES: Epilepsy during the pregnancy is an important problem in clinical practice for newborn individuals. Recently, it has been demonstrated that mothers' epileptic seizures have some harmful effects on newborns, but present data concerning the effects of epileptic phenomena in pregnant mothers on newborn pups are still limited. The current study was undertaken to investigate the morphological changes in the hippocampus of newborn pups of pinealectomized rats subjected to experimental epilepsy during pregnancy. METHODS: In this study, rats were randomly divided into four groups (ten animals each): intact control group, epilepsy control group, surgical pinealectomy + epilepsy group, and group with melatonin treatment following pinealectomy procedure. The animals in surgical pinealectomy + epilepsy and melatonin treatment groups underwent a surgical intervention consisting of pineal gland removal. At 1 month after surgical pinealectomy, an acute grand mal epileptic seizure was induced by 400 IU penicillin G administration into their hippocampal CA3 region on the 13th day of their pregnancy in all animals except the intact control animals. On the first neonatal day, the hippocampi were removed and processed for microscopic examination. Nestin expression was analysed in the developing hippocampal tissue. RESULTS: Normal migration and hippocampal maturation were determined in the postnatal rat hippocampus in intact control group, but the morphological structure of the hippocampus in the epilepsy control group corresponded to the early embryonal period. It was found that experimental epilepsy and pinealectomy enhanced nestin immunoreactivity, whereas exogenous melatonin treatment (30 mug/100 g body weight, intraperitoneal) inhibited pinealectomy-stimulated nestin expression in CA1 region of the hippocampus. CONCLUSION: These findings suggest that epileptic seizures during pregnancy may cause an impaired hippocampal neurogenesis and neuronal maturation in the newborn, and the negative effects in the postnatal rat hippocampus are more dramatic after pinealectomy of the mother; conversely, melatonin administration suppresses these negative changes. This is the first report investigating the effects of maternal epilepsy during pregnancy in pinealectomized rats on nestin immunoexpression in the newborn rat hippocampus.

Analysis of Variance↗
PubMed2005

Neonatal pinealectomy induces Purkinje cell loss in the cerebellum of the chick: a stereological study.

Melatonin plays an important role in certain physiological functions and morphological features of various structures. In the current study, the effects of pinealectomy on Purkinje cell number and morphological features of developing cerebellum in the chick were investigated using stereological methods. Fifteen Hybro Broiler newly hatched chicks were divided into three groups: a pinealectomized group (n = 5), sham-operated group (n = 5) and a non-pinealectomized control group (n = 5). Surgical pinealectomy was performed in 3-day-old chicks. In the 8th week, all animals were sacrificed for histopathological evaluation and subsequent stereological analysis. Each layer volume of molecular (+Purkinje cell), granular and white matter in the cerebellum was estimated in all animals. It was found that there was no significant difference for the volume of whole cerebellum and also molecular (+Purkinje cell) layer in these groups (P > 0.05). Nevertheless, the values of granular layer and white matter of sham-operated group were significantly different from those of control and pinealectomized animals (P < 0.01). It was also observed that pinealectomy significantly reduces the Purkinje cell number in cerebellar cortex (P < 0.01). The present study is the first stereological study to demonstrate the histomorphological effects of pinealectomy on the cerebellum in the chick. Our results suggest that pineal gland/melatonin might play an important role in morphological features of the developing cerebellum in the chick.

Animals↗
PubMed2005

Beneficial effects of melatonin on morphological changes in postnatal cerebellar tissue owing to epileptiform activity during pregnancy in rats: light and immunohistochemical study.

Although it has been demonstrated that maternal epilepsy has some harmful effects on newborn individuals, current data concerning the effects of epileptic phenomena in pregnant mothers on newborn pups are still limited. This study was undertaken to investigate the changes in the cerebellum of newborns of pinealectomized rats subjected to experimental epilepsy during pregnancy. In our study, the rats were randomly divided into six groups: intact control group, anesthesia control group, epilepsy group, melatonin-treated epileptic group, surgical pinealectomy group, and group of melatonin treatment following pinealectomy procedure. At 1 month after pinealectomy, an acute grand mal epileptic seizure was induced by 400 IU penicillin-G administration into their intrahippocampal CA3 region during the 13th day of their pregnancy in all animals except intact control group. On the neonatal first day, pups were perfused transcardially and the cerebellums removed were processed for light microscopic and immunohistochemical studies. Normal migration and maturation were determined in the postnatal rat cerebellum in both intact control and anesthesia (ketamine-xylazine) control groups, but the morphological structure of cerebellum in the epilepsy control group corresponded to the early embryonal period. It was found that experimental epilepsy or pinealectomy procedure enhanced nestin immunoreactivity, but exogenous melatonin treatment (30 microg/100 g body weight, i.p.) following pinealectomy inhibited increased nestin expression induced by melatonin deprival in vermis region of newborn rat cerebellum (P < 0.001). Our results confirm that epileptic seizures during pregnancy may impair neurogenesis and neuronal maturation in newborns, which are more dramatic in the presence of melatonin deficiency during pregnancy, explaining more harmful effects of epileptic seizures to embryos of aged mothers. To the best of our knowledge, this is the first study reporting the effects of maternal epilepsy during pregnancy in pinealectomized rats on nestin immunoexpression in the newborn rat cerebellum.

Animals↗
PubMed2005

Hydatidosis of the orbit in Turkey: results from review of the literature 1963-2001.

Hydatidosis can involve almost every organ or tissue in the body via the systemic circulation, but hydatid infestation of the orbit comprises far less than 1% of the total incidence. This study investigated the data on all patients of orbital hydatid disease reported in Turkey since 1963. In this meta-analysis, a total of 25 patients were included and slowly progressive unilateral proptosis, with or without pain, was the most frequent clinical manifestation (80%). The other presenting symptoms were visual loss (48%), periorbital pain (24%), chemosis (16%), and headache (12%). The presumptive diagnosis of hydatid cyst was made on the images obtained from ultrasonography (US), computed tomography (CT) and/or magnetic resonance imaging (MRI) examinations. These diagnostic studies demonstrated a well-circumscribed cystic mass in almost all patients. Total surgical removal without rupture remains the best mode of therapy for orbital hydatid disease. The study indicates that in Turkey hydatidosis remains a serious problem, causing blindness. Orbital hydatid cyst should be included in the differential diagnosis of unilateral proptosis and visual handicap in patients from countries where hydatidosis is endemic.

Conjunctival Diseases↗
PubMed2005

Surgical pinealectomy accelerates intervertebral disc degeneration process in chicken.

Despite the importance of intervertebral disc (IVD) degeneration both in research and clinical practice, the underlying biological mechanism of this phenomenon remains obscure. The current study investigated the effects of neonatal pinealectomy on the development of IVD degeneration process in chicken. Thirty chicks (3 days of age) were divided into two equal groups: unoperated controls (Group X) and pinealectomized chicks (Group Y). Pinealectomies were performed at the age of 3 days. At the age of 8 weeks, magnetic resonance imaging examination of one animal in each experimental group was taken. At the end of the study, serum melatonin level was determined by using ELISA method and histopathological or biochemical examination of specimens from all subjects was done. The results of biochemical analyses were compared using Mann-Whitney U test, whereas The Chi-square test was adopted for the histological findings. In this study, the serum melatonin levels in Group Y were significantly lower than those in Group X (P < 0.001). Similarly, scoliosis was developed in 14 out of 15 (93%) in Group Y. Hydroxyproline content of IVD tissue was high in Group Y compared with the values in Group X, although there was no significant difference. Histologically, an appearance of normal IVD was observed in Group X, while the presence of a degenerated IVD was observed in Group Y. From the results of the current study, it is evident that surgical pinealectomy in new-hatched Hybro Broiler chicks has a significant effect on serum melatonin level as well as on the development of IVD degeneration and spinal malformation. In the light of these results from present animal study, melatonin may play a role in the development of IVD degeneration in human beings, but this suggestion need to be validated in the human setting.

Animals↗
PubMed2005

Chronic changes in cerebrospinal fluid pathways produced by subarachnoid kaolin injection and experimental spinal cord trauma in the rabbit: their relationship with the development of spinal deformity. An electron microscopic study and magnetic resonance imaging evaluation.

Post-traumatic cystic changes in cerebrospinal fluid (CSF) pathways such as ventriculomegaly and/or hydrosyringomyelia are not uncommon, but their characteristics have not yet been fully clarified. This study was designed to investigate the alterations affecting the CSF pathways in rabbits at a late stage, and to clarify the relationship between these changes and the development of spinal deformity. In this study, a total of 60 New Zealand white rabbits were used and they were segregated into four different groups of 15 animals each: sham-operation group, kaolin group, and kaolin plus mild trauma group and kaolin plus severe trauma group. The animals were subjected to radiological investigation using direct X-ray study and magnetic resonance imaging (MRI) after 4 months. The thoracic spinal cords of the animals were dissected after intracardiac perfusion-fixation with 10% formalin for light microscopy and 2.5% glutaraldehyde for transmission electron microscopic study. Following the sectioning and staining procedures, the histological characteristics of the spinal cords were evaluated with light microscopy and transmission electron microscopy. A spinal deformity developed in 90% in rabbits in both kaolin injection group and spinal trauma groups. MRI revealed generalized dilatation of the ventricular system and the central canal of the spinal cord after the kaolin injection with/without trauma in this study. Gross morphologic examination showed some enlargement of entire CSF pathways in these groups. All animals with central canal dilatation had mild or severe scoliotic and kyphotic deformities. In a light microscopic study, a denuded ependymal line and multicyst formations in periependymal areas were found in both kaolin injection and spinal trauma groups. Ultrastructurally, an apical flattening of the ependyma, microcysts in the ependymal cells, axonal degeneration, demyelination, and loss of ependymal cells adjacent mild spongy were found in the spinal cords of animals in these groups. To the best of our knowledge, this is the first study to investigate the chronic effects of spinal cord injury (SCI) on the CSF pathways and their relationship with the development of spinal deformity in an experimental model of kaolin injection and trauma, using MRI as well as light and transmission electron microscopy. In the light of this study, the severity of spinal cord injury on the development of some degenerative findings in the spinal cord was clear, but further clinical and experimental studies using dynamic imaging techniques will be valuable.

Animals↗
PubMed2005

Role of the AZFd locus in spermatogenesis.

To determine the prevalence of Y-chromosome microdeletions among infertile men and to correlate the clinical presentation of the men with specific deletions, microdeletion analysis in 53 infertile men (30 nonobstructive azoospermic, 23 severely oligozoospermic patients), and 100 age-matched, fathered normospermic men who had fathered children was performed by the multiplex PCR with 18 different Y-chromosome-specific STS primer sets, spanning the AZFa, AZFb, AZFd, and AZFc regions. Detection of the same locus deletion of the AZFd region in three cases indicated the possible importance of the genes located in this region in spermatogenesis.

Chromosome Deletion↗
PubMed2005

Fibroepithelial polyp of glans penis.

A case of fibroepithelial polyp of the penis in a 59-year-old man is presented. The physical examination showed that the lesion affected the ventral surface of the glans, near the urethral meatus. No communication was found with the urethra. The patient had a history of long-term condom catheter use. He was successfully treated by wide local excision. The histopathologic diagnosis was a fibroepithelial polyp. Postoperatively, the follow-up examinations at 3, 6, 12, and 24 months showed normal findings and no recurrence.

Humans↗
PubMed2005

Pinealectomy exaggerates and melatonin treatment suppresses neuroma formation of transected sciatic nerve in rats: gross morphological, histological and stereological analysis.

At present, an intensive effort for prevention of neuroma formation following peripheral nerve section continues. It has been recently suggested that surgical pinealectomy (Px) induces elevation of the collagen content in the granulation tissue of a wound, while melatonin application after Px suppresses elevation of the collagen accumulation in the tissue. The aim of the present study was to assess whether melatonin had the ability to suppress collagen production and neuroma formation following peripheral nerve transection. A total of 40 male rats (four groups of 10) were left intact (intact controls) or sham operated (sham group), were Px, or were Px and given melatonin (Px + melatonin group). All animals underwent a surgical intervention consisting of right sciatic nerve neurectomy. After 4 wk, the animals were killed following intracardiac perfusion. Gross morphology of neuroma formation in the proximal nerve segment was examined and proximal neuroma evaluated. Macroscopic and microscopic findings revealed that Px caused a proliferation of connective tissue and large neuroma formation at the proximal ends of transected nerves. Stereological analysis showed that there was a statistically significant reduction in connective tissue content of the same region in Px animals treated with melatonin (P < 0.005). The results achieved in a rodent model of sciatic nerve neuroma formation showed that there was a positive correlation between macroscopic and microscopic observations, and that melatonin enhanced axonal regeneration presumably due to its inhibitory effect on neuroma formation.

Animals↗
PubMed2005

Morphological, stereological and radiological changes in pinealectomized chicken cervical vertebrae.

Considerable evidence supports the hypothesis that melatonin plays an important role in osteogenesis. We carried out an experiment to investigate histological and radiological changes in the cervical vertebrae of pinealectomized chickens. Thirty new-hatched chicks were divided into two groups: pinealectomized group (n=15) and nonpinealectomized control (n=15). Surgical pinealectomies were performed in Hybro broiler chickens at the age of 3 days. At 8 wk, one animal from each group was examined using computed tomography scanner to obtain density histograms of four consecutive vertebrae between the 4th and 7th cervical vertebral segments of chickens. At the end of the study, all animals were killed for subsequent measurement of bone mineral density (BMD) and macroscopic, radiographic and histopathological evaluation of specimens. We found that the profile of the density histogram in nonpinealectomized control group showed a spike profile for the vertebral body, indicating an increase in the amount of higher density tissues in this region, while a plateau-shaped profile was obtained for the vertebral body in pinealectomy group, indicating the presence of heterogenous bone tissue. Accordingly, the mean value of BMD in pinealectomy group was significantly lower at the vertebral body in chickens compared with control subjects (P<0.001). At the end of the experiment, almost all of the chickens in pinealectomy group developed a scoliotic curvature and the mean weight and length of the cervical vertebral bodies of the pinealectomized chickens were significantly lower than those of control group (P<0.001). Although the numerical density of osteocytes and osteoblasts in pinealectomy group was significantly higher than that from the control group, total number of osteocytes but not osteoblasts in cervical vetrebrae from pinealectomized animals was significantly lower than that from nonpinealectomized control animals (P<0.05). In conclusion, the results of the current study demonstrated for the first time pinealectomy-induced histomorphometrical changes in chicken vertebral column using stereological methods, suggesting that pineal gland/melatonin may have an osteoinductive effect on bone formation, but further studies are needed to elucidate the relationship of our findings with some disorders such as postmenopausal and/or senile osteoporosis.

Animals↗