Browsing by Author "Umur, AS"
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Item Adult tethered cord syndrome mimicking lumbar disc diseaseUmur, AS; Selcuki, M; Selcuki, D; Bedük, A; Doganay, LObject This paper reports four tethered cord cases who initially applied with lumbar disk disease symptoms. Materials and methods All of them were investigated by magnetic resonance imaging (MRI) and somatosensory evoked potential (SSPE). In two patients, MRI revealed thick and fatty filum terminale, while in remaining two, the filum terminale appeared as normal in thickness. SSEP revealed pathological conduction values in all, and it was the main indicator for surgical sectioning in patients especially with normal MRI investigations. All patients had benefit from the surgical sectioning of the fila terminalia with either thick and fatty or normal appearance. Conclusion A particular patient with lumbar disc disease symptoms having normal MRI should also be investigated for tight filum terminale. If there is no pathological appearance in MRI investigation (both in regard to disc herniation and thick and fatty filum terminale), SSEP investigation should be done to check whether a conduction block or delay is present, indicating cord tethering.Item TGF-βs and SMADs Activities at the Site of Failed Neural Tube in the Human EmbryosBarutcuoglu, M; Umur, AS; Vatansever, HS; Umur, N; Ozbilgin, K; Sayhan, S; Selcuki, MAIM: Transforming growth factor beta (TGF-beta) and Smads control intracellular signaling pathways in neurulation. Although previously reported similar experimental animal studies, the aim of this human study is to investigate the expression of TGF-beta (1,2,3) and Smads (1,2,3,6,7) in aborted human fetuses with myeloschisis. MATERIAL and METHODS: Twelve human fetuses with neural tube defect were obtained. They were stained with antibodies against TGF-beta 1, TGF-beta 2,TGF-beta 3, Smad (1,2,3), Smad 6 and Smad 7 using the indirect immunohistochemical technique. RESULTS: We noted mild immune reactivity of TGF-beta 1 and TGF-beta 2 in the open neural plate, motor neurons and surrounding tissue. Strong immune reactivity of TGF-beta 3 was shown in only open neural plate and surrounding tissue. Immunoreactivity of all Smads noted negative except Smad7. CONCLUSION: These results suggested at the site where the neural tube failed to close, TGF-beta 1,2 and Smads 1,2,3,6 do not continue their activity and decrease with internal timing of embryonic development. Additionally ectodermal layers are considered by embryo asnot closed wound and TGF-beta 3 activity may be an effort to repair the failed closure.Item The Effects of Meloxicam on Neural Tube Development in the Early Stage of Chick EmbryosCetinkal, A; Colak, A; Topuz, K; Demircan, MN; Simsek, H; Berber, U; Umur, AS; Selcuki, M; Vatansever, HSAIM: The aim of this study is to demonstrate the effect of meloxicam in early stage chick embryos on neural tube development. MATERIAL and METHODS: One hundred specific pathogen-free (SPF) chicken eggs were used to investigate the neurulation. SPF eggs were invastigated in four groups (n:25). All of the groups were incubated at 37.2 +/- 0.1 degrees C and 60 +/- 5% relative humidity for 30 hours, and an embryological development in the ninth stage as classified by Hamburger and Hamilton was obtained. In the end of the 30th hour, group A (control group) was administered 0.1 ml of saline (0.9% NaCl) in ovo and the other groups were administered meloxicam in increasing doses. At the end of 72 hours, all of the embryos were extracted from eggs and they underwent pathological examination with hematoxylin cosine and immuno-histopathological examinations with CD138 and tubulin beta II. RESULTS: While the groups A and B showed no neural tube defects, totally eight defective embryos were detected in the groups C and D (three in group C and five in group D. CONCLUSION: Our results suggested that meloxicam, a nonselective COX inhibitor, caused neural tube closure defects when injected at supratherapeutic doses. However, further studies with larger numbers of subjects are needed for its use in lower doses.Item Inhibiting effect of oleocanthal on neuroblastoma cancer cell proliferation in cultureÜnsal, ÜÜ; Mete, M; Aydemir, I; Duransoy, YK; Umur, AS; Tuglu, MIWe investigated the potential anticancer effects of oleocanthal (OC) on neuroblastoma cells. Cells were divided into four groups: group 1, neuroblastoma cells were treated with OC; group 2, neurons that differentiated from neuroblastoma cells were treated with phosphate-buffered saline(PBS); group 3, bone marrow derived neuronal (BMDN) cells that were differentiated from bone marrow derived mesenchymal stem cells (BMSCs) were treated with OC; group 4, BMDN cells that were differentiated from BMSCs were treated with PBS. Groups 2 and 4 were control groups. The effects of OC on cell viability, oxidative stress, neurite inhibition and apoptosis at IC50 dose were investigated using MTT analysis, i-NOS and e-NOS measurement, neurotoxicity screening test (NST) and TUNEL staining, respectively. MTT analysis demonstrated that cells were significantly less viable in group 1 than in group 3. i-NOS and e-NOS staining intensity was significantly greater in group 1 than in group 3. NST revealed that OC inhibited neurite growth in both neuroblastoma and BMND cells; inhibition was significantly less in group 3 than in group 1. Significantly more TUNEL labeled cells were found in group 1 than in group 3. We found that OC prevented growth and proliferation of neuroblastoma cells in culture by increasing oxidative stress and apoptosis. We also found that the cytotoxicity of OC is negligible in BMDN cells.Item Evaluation of the Effects of Mobile Phones on the Neural Tube Development of Chick EmbryosUmur, AS; Yaldiz, C; Bursali, A; Umur, N; Kara, B; Barutcuoglu, M; Vatansever, S; Selcuki, D; Selcuki, MAIM: The objective of this study is to examine the effects of radiation of mobile phones on developing neural tissue of chick embryos. MATERIAL and METHODS: There were 4 study groups. All Groups were placed in equal distance, from the mobile phones. Serial sections were taken from each Group to study the neural tube segments. RESULTS: The TUNEL results were statistically significant (p<0.001) at 30 and 48 hours in the third Group. We found low Bcl-2 levels partly in Group 4 and increased activity in Group 3. Caspase-3 was negative in the 48 and 72 hours in the Control Group, had moderate activity in the third Group 3, weak activity in the 48 hour, and was negative in the 72 hour in other groups. Caspase-9 immunoreactivity was weak in Group 1,2 and 3 at 30 hours and was negative in Group 1 and 4 at 48 and 72 hours. Caspase-9 activity in the third Group was weak in all three stages. CONCLUSION: Electromagnetic radiation emitted by mobile phones caused developmental delay in chick embryos in early period. This finding suggests that the use of mobile phones by pregnant women may pose risks.Item Analysis of the Effects of Inhibitor and Activator Systems (Smad's Proteins) of TGF-βs on Chick Neural Tube ClosureUmur, N; Vatansever, S; Umur, AS; Özbilgin, K; Selçuki, MThe families of TGF-beta s and Smads proteins that controls its intracellular signaling pathways are known to play a role in early neurulation. The aim of this study is to demonstrate distribution of TGF-beta s (1, 2, 3) and Smads (1/2/3, 6, 7) proteins as a system in different hours of neural tube development of chick embryos. The SPF eggs were incubated at 37.8 +/- 2 degrees C for 24(th), 30(th), 48(th), 72(nd) h. After that, embryos were examined using immunohistochemistry and western blotting techniques. To the results, TGF-beta s immunoreactivities (particularly TGF-beta 3) at the 24(th), 30(th) and 48(th) h of chick development (during neural tube closure) were determined and decreased at the 72nd h (after neural tube closure), but expressions of TGF-beta s were detected in all stage of embryos in western blotting. While Smad 1/2/3 immunoreactivitiy and expression was less than that of the Smad 6 and 7 at the 24(th), it was increased at the 30(th) h. Smads proteins immunoreactivities were decresead at the 72(nd) h. In conclusion, the members of TGF-beta s are play a role in chick neural tube closure, the secretions of TGF-beta s are controlled different Smad proteins. In addition, immunoblotting results showed that TGF-beta s and Smads proteins were effective in the development of all tissues and organs of the embryos.Item The effects of methotrexate on the development of neural tube defects in the chick embryoVatansever, HS; Umur, AS; Inan, VS; Selçuki, MDuring chick development, one of the earliest differentiated tissues is the neural tube. After 24 h of incubation, a chick egg starts to differentiate and 30-48 h after incubation the neural plate is closed from head to tail to form the neural tube. If factors controlling the neural tube's closing are disrupted, this consequently causes neural tube closure defects during this time. In this study, the effect of methotrexate on the developing neural tube was investigated during early chick development. For this research, 40 specific pathogen free (SPF) white Leghorn type chick embryos were used. They were incubated for 30 h at 37.8 +/- 2 degreesC. Methotrexate, which inhibits the 2 dihydrofolate reductase enzyme by a competitive mechanism, was injected within therapeutic dosage limits (10 mg/m(2), 20 mg/m(2), 40 mg/m(2)) in ovo. Ten eggs were injected with 0.9% NaCl and used as a control group. All groups, after the injection, were incubated for 48 and 72 h. They were then dissected and the embryos were fixed in 10% (v/v) formalin for 2 h. The embryos were embedded in paraffin wax and 5 p serial sections were taken. Sections were stained with haematoxylin and then observed under light microscopy. While 20 mg/m(2) or 40 mg/m(2) methotrexate embryos were not alive when they were opened at 48 h incubation, 10 mg/m(2) methotrexate embryos maintained normal development after 48 and 72 h incubation. However, there was developmental retardation in the methotrexate injected group when compared with the control group with development of the brain being retarded; the volume of brain vesicles was lower than in the control group. Our results suggested that methotrexate, an antimetabolite of folic acid, caused neural tube closure defects when injected at therapeutic dosage levels. Folic acid is essential for normal development of the nervous system; therefore, folate antagonists might be more harmful to the central nervous system than to other parts of the developing body.Item Scoliosis may be the first symptom of the tethered spinal cordBarutçuoglu, M; Selçuki, M; Umur, AS; Mete, M; Gurgen, SG; Selcuki, DBackground: Tethered cord syndrome (TCS) is a progressive clinical entity that arises from abnormal spinal cord tension. Scoliosis may be a unique symptom in TCS. The aim of this study is to investigate prognosis after releasing the filum terminale in scoliosis due to TCS with/without findings in magnetic resonance imaging (MRI) and to draw attention to the importance of somatosensorial evoked potentials (SSEP) on the differential diagnosis of idiopathic scoliosis versus scoliosis due to TCS with normal appearance of filum terminale and conus medullaris. Materials and Methods: Eleven female and seven male patients with progressive scoliosis were included in the study. They were evaluated radiologically, SSEP and urodynamical studies. Preoperative and postoperative anteroposterior full spine X-rays were obtained for measuring the Cobb's angle. MRI was performed in all cases for probable additional spinal abnormalities. All patients underwent filum terminale sectioning through a L5 hemilaminectomy. The resected filum terminale were subjected to histopathological examination. Results: The mean Cobb angle was 31.6 degrees (range 18 degrees u45 degrees). Eight patients (44.45%) had a normal appearance of filum terminale and normal level conus medullaris in MRI, but conduction delay and/or block was seen on SSEP. In the histopathological examination of filum terminale dense collagen fibers, hyaline degeneration and loss of elastic fibers were observed. Postoperatively none of the patients showed worsening of the Cobb angle. Three patients showed improvement of scoliosis. Conclusion: In TCS presented with scoliosis, untethering must be performed prior to the corrective spinal surgery. Absence of MRI findings does not definitely exclude TCS. SSEP is an important additional guidance in the diagnosis of TCS. After untethering, a followup period of 6 months is essential to show it untethering helps in stopping the progress of the scoliotic curve. In spite of non progression (curve stopped lesser than 45 degrees) or even improvement of scoliosis, there may be no need for major orthopedic surgical intervention.Item Apoptosis seems to be the major process while surface and neural ectodermal layers detach during neurulationSelcuki, M; Vatansever, S; Umur, AS; Temiz, C; Sayin, MObjective The aim of this study is to demonstrate the process of detaching neural and surface ectodermal layers soon after the neurulation completes. Materials and methods Specific pathogen-free chicken egg embryos were used to investigate the neurulation procedure. Ten eggs were saved as controls. The other ten eggs were opened at the 30th hour of embryo development and cultured with Z-VAD-FMK (peptide caspase inhibitor) to investigate the results of the apoptosis inhibition. Embryos were placed and developed up to 48 h in the culture medium. To detect apoptotic cells between neural and surface dermal layers, immunoreactivity of p53 and terminal uridine deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were used. Results While the control group shows positive immunoreactivity of p53 and TUNEL-positive apoptotic cells at the site where the neural folds detach from the surface ectoderm, no TUNEL activity and no detachment were detected in the apoptosis-inhibited group. Conclusion As inhibition of apoptosis prevented the detachment of the neural and surface ectodermal layers from each other at the end of the neurulation, inhibition of apoptosis seemed to cause a considerable embryological error accounted for congenital dermal sinus tractus maldevelopment.Item Tethered Cord Syndrome in Adults: Experience of 56 PatientsSelcuki, M; Mete, M; Barutcuoglu, M; Duransoy, YK; Umur, AS; Selcuki, DAIM: The aim of this study was to describe the results of surgery performed in a group of adult patients with tethered cord syndrome with their outcomes. MATERIAL and METHODS: This retrospective study included 56 patients. There were 38 females and 18 males. All patients were older than 18 years. RESULTS: The mean age at referral was 36 years and 1 month. The mean follow-up period was 10 months 27 days. 95% of all patients with back and leg pains improved and 5% remained the same. Three patients with motor deficits remained the same in the postoperative period. Of the 16 patients with urological complaints, 10 improved, 5 unchanged and 1 patient died in the postoperative first day due to pulmonary embolism. CONCLUSION: The syndrome of tethered cord may be a situation to be treated even in the elderly in case of normal level conus medullaris and filum terminale with a normal appearance as well as a low-lying conus and thick filum. To prevent overlooking the diagnosis of tethered cord and/or unnecessary spinal surgeries, the tethered cord syndrome should be remembered in the differential diagnosis list in the presence of back and leg pains, neurological deficits or urological complaints.Item The Differentiation of Neuronal Cells from Mouse Embryonic Stem CellsUmur, N; Vatansever, HS; Umur, AS; Türköz, E; Özbilgin, KWith new technologies emerging today, the importance of stem cells in the cell therapy of nervous system diseases is supported by recent studies. Therefore, the development of neuronal cell differentiation protocols from stem cells is of great importance. In our study, the differentiation of neuronal and neuroglial cells from mouse embryonic stem (ES) cell line and their analysis with neuronal cell markers are aimed. Mouse ES cells were differentiated to neurogenic series cells by adding N2 and bFGF to the culture medium on coated Fibronectin dishes. For the identification of differentiated cells, they were evaluated by light microscopy using immunhistochemistry techniques and by electron microscopy. Indirect immunohistochemical staining method was performed with SSEA-1 (mouse embriyonic stem cells marker), Nestin (neural precursor cells marker), beta III-Tubulin (neuronal cells marker), MAP-2 (neuronal cells marker), GFAP (astrocyte marker), and O4 (oligodendrocyte marker). After 1 week of differentiation of cells, immunoreactivities of SSEA-1 and Nestin were detected to be negative and moderate, respectively. After 2 weeks culture time, the differentiation was still continuing and especially positive immunoreactivities of beta-III Tubulin and MAP-2 and weak immunoreactivities of O4 and GFAP were supported neuronal differentiation. In conclusion, our results suggest that neuronal cell derived from mouse ES cells were differentiated particularly to neuron using N2+bFGF+fibronectin culture condition. Therefore, these differentiated cells may be used as a treatment method in degenerative diseases of the nervous system.Item Congenital Dermal Sinus Tract of the Spine: Experience of 16 PatientsMete, M; Umur, AS; Duransoy, YK; Barutçuoglu, M; Umur, N; Gurgen, SG; Selçuki, MCongenital dermal sinus tract is a rare entity which lined by epithelial cells and can end anywhere between subcutaneous planes to thecal sac. These tracts may be accompanied with other pathologies such as lipomyelomeningocele, myelomeningocele, split cord malformation, tethered cord, filum abnormality and inclusion tumors and treatment includes resection of tract with intradural exploration. The authors review their experience with 16 cases. Clinical, radiological appearance and treatment of these lesions discussed with literature review.Item Use of Chicken Embryos as an Angiogenesis Model for Central Nervous System Malignant Tumor ResearchUmur, N; Gurgen, SG; Sarsmaz, HY; Umur, ASAIM: To demonstrate the usability of chicken chorioallantoic membrane (CAM) as an angiogenesis model for the development and treatment of malignant tumors of the central nervous system. MATERIAL and METHODS: A fresh tumor tissue piece taken from Glioblastoma patients, a malignant tumor of the central nervous system, was transferred to the CAM of chicken embryos and left to incubate in the incubator and their development was monitored. After examining the results of the study macroscopically, CAM tissue samples were evaluated both histochemically and immunohistochemically in terms of angiogenic factors VEGF (Vascular Endothelial Growth Factor), bFGF (basic Fibroblast Growth Factor) and PDGF (Platelet Derived Growth Factor). RESULTS: According to histochemical findings obtained from our study when compared with control embryos, blood vessels, fibroblast count and inflammatory infiltration were observed more in the tumor transplanted groups, especially in the tumor -developing CAM region. There was also intense pleomorphism and marked hypercellularity in the cells. In our immunohistochemical findings, it was determined that bFGF, PDGF, VEGF staining intensities were higher in tumor transplanted groups compared to control groups, and this elevation was more pronounced in the tumor-developing region. CONCLUSION: As a result, it has been shown that the chicken embryo CAM model may be a suitable in vivo model for cancer angiogenesis studies. The protocol we created in this study will be a source for projects related to the use of therapeutic agents in cancer angiogenesis.Item Split Cord Malformation Type II Associated With Double Lipoma at The Same Level: Report of a Rare CaseMete, M; Gursoy, G; Umur, AS; Selçuki, MSplit cord malformations are classified as type I and type II and can be associated with lipomyelomeningocele. Although multiple lipoma in different levels at the same patient has been described, combination of SCM with double lipoma at the same level in literature is only once described previously. Herein, authors presented a 12 years old girl who had SCM type II associated with double lipoma at the same level.Item A giant hypertrophy of C5 spinous process in Klippel-Feil syndromeMete, M; Ünsal, ÜÜ; Duransoy, YK; Umur, AS; Selçuki, MCongenital cervical spinal anomalies are relatively common and can be seen in upper and lower cervical regions. However, hypertrophy of the lamina and spinous process of cervical vertebra is extremely rare. Here we reported an 11-year-old girl with unilateral hypertrophy of the lamina and spinous process of C5 vertebra coexistence with Klippel-Feil syndrome, occipitalization of atlas and atlantoaxial congenital fusion. Because of cosmetic anomaly patient underwent surgery and spinous process excised. To the best of our knowledge, this coexistence of congenital cervical bony anomalies in a child has not been reported previously in English literature.Item Inappropriate surgical interventions for midline fusion defects cause secondary tethered cord symptoms: implications for natural history report of four casesSelçuki, M; Umur, AS; Duransoy, YK; Ozdemir, S; Selcuki, DThe causes of tethered spinal cord are various. In order to release the tethering effect of these malformations, the surgical interventions must include removal of all tethering components, reconstruction of the neural tube and sectioning of tight filum terminale as well. The cases reported in this paper have had an operation many years before for various developmental defects. After a certain period of time (5-10 years) of the first operation, the patients reapplied to the hospital with various symptoms of spinal cord tethering, either vertical or horizontal. At surgical intervention, it was noted that inappropriate surgical procedures caused retethering of the spinal cord in all patients. Postoperative period of all patients were uneventful. All patients declared relief in their symptoms. We would like to draw attention that untreated (or inappropriately treated) midline developmental defects will invariably cause syndrome of tethered cord. Consequently, prophylactic surgical untethering must be applied to all patients with developmental midline defects as soon as possible. It looks that tethered cord symptoms invariably appear as enough negative influence accumulates as the time passes. Elapsed time may vary but unpleasant end result invariably arrives. While these cases with tethered spinal cord develop progressive neurological symptoms, prophylactic and appropriate surgical intervention should be considered as early as possible. There is no acceptable rationale to wait for the appearance of tethered cord syndrome symptoms to perform surgical untethering of the spinal cord because of the probability of irreversibility of the symptoms (incontinence of urine in particular) of tethered spinal cord syndrome.Item Simultaneous folate intake may prevent advers effect of valproic acid on neurulating nervous systemUmur, AS; Selcuki, M; Bursali, A; Umur, N; Kara, B; Vatansever, HS; Duransoy, YKThe aim of this study is to elucidate the preventive effect of folic acid (FA) on teratogenic effects of valporic acid (VA) in early stage chick embryos on neural tube development. One hundred and fifty specific pathogen-free (SPF) chick eggs were used to investigate the neurulation in five groups. Group A was the control group. Group B was injected 0.02 ml of saline (0.9% NaCl) and was used for sham group. VA (0.72 mg) in 0.02 ml saline was injected in Group C, and 0.342 mcg of FA in 0.02 ml NaCl were administered to the embryos in Group D. VA (0.72 mg) + 0.342 mcg of FA in 0.02 ml saline were administered simultaneously to the eggs in Group E. At the end of 72 h, all embryos were extracted from eggs and were fixed, and for histological analyses hematoxylin and eosine was used, for detection of apoptotic cells terminal deoxyribonucleotide transferase-mediated dUTP-X nick end labeling (TUNEL) was used and for distribution of P53, bcl-2 and caspase-3, caspase-6, caspase-8 and caspase-9 immunoperoxidase techniques were used. While there were no neural tube defects in the embryos of groups A, B and D, eight embryos died in group C and there were 12 embryos with retarded embryological development. In contrast to that, no death was observed in group E, but only eight embryos were detected with maldevelopmental delay stage. These results suggested that VA may induce apoptotic mechanisms but not through the p53 pathway. In addition, FA effectively prevents the teratogenic influence of VA on chick embryo at neurulation stages by stopping cascade of apoptosis before caspase 3 expression.Item Pseudomonas Sepsis and Multiple Brain Abscesses in a Newborn Infant Following Neurosurgical Procedure for MeningoceleBilgili, G; Ergon, EY; Kara, B; Özyurt, M; Ovali, GY; Umur, AS; Selçuki, MIntroduction: Postneurosurgical brain abscess carries a high risk of neurologic morbidity and mortality. Case Presentation: A newborn infant had Pseudomonas sepsis and multiple brain abscesses after meningocele repair, and was successfully treated medically. Conclusion: Prompt recognition of this life-threatening condition is crucial.Item Preoperative and Postoperative Evaluation of Somatosensorial Evoked Potentials of Upper Extremities in Cervical Intervertebral Disc HerniationUmur, AS; Selcuki, M; Selcuki, D; Temiz, C; Akbasak, AThis study aims to determine the dysfunction caused by existing pathological condition in structures involved in the transfer of sensory functions of the neural system in cervical disc herniation, and to establish whether or not the level and degree of this anatomical damage can be anticipated by SEP (Somatosensorial Evoked Potentials). We compared the obtained SEP values for statistical significance using the Friedman Variation Analysis. In parameters with statistical significance, the Wilcoxon Signed Rank test was used to identify when significant improvements occurred. The study found that the statistical data of the latency of the N14 wave originating from the dorsal column nuclei of the medulla spinalis and dorsal column gray matter improved (p<0.05) in the postoperative period compared with the preoperative values. Using the Wilcoxon Signed Rank test, we studied postoperative months separately in regard to the difference in the latency of the N14 wave, and found the statistically significant improvement to be marked particularly in months 3 and 6 postoperatively (p<0.05). In conclusion, we suggest that SEP is a useful tool to check the functional condition of the dorsal spinal column. The benefit of the SEP utilization is the ability to determine the severity of the pathological condition preoperatively and follow the patient's functional postoperative improvement.Item Effect of sodium phenytoin concentration on neural tube development in the early stages of chicken embryo developmentTemiz, C; Temiz, P; Demirel, A; Sayin, M; Umur, AS; Özer, FDAnimal and human research has shown that anticonvulsants are teratogens and pose a risk of causing fetal malformations. In various studies, the teratogenic effects of sodium phenytoin (PTH) in several systems have been investigated. Toe and finger, renal, and even facial malformations have been described in the literature. However, there is debate about whether the true risk of teratogenesis is lower or higher than previously reported for PTH. There is also little published information on the effect of this agent on neural tube closure in an embryological model. In this study, 0.1 mL of three different concentrations of PTH solution (mg/mL: 1, 3, 5) or vehicle was applied under the embryonic disc of specific pathogen-free Leghorn chicken embryos after 24 hours' incubation. Incubation was continued until 72 hours of maturation. At 72 hours, all embryos were evaluated macroscopically and microscopically. There were serious neural tube closure defects in the embryos administered large amounts (0.5 mg) of PTH, but doses of 0.1 mg (subtherapeutic concentration for humans) and 0.3 mg (therapeutic concentration for humans) produced no statistically significant defects (p = 0.05). The difference between the defects in the high concentration group and the other three groups was statistically significant. In our study PTH administered in a strict concentration regimen produced a lower level of neural tube closure-related defects than previously reported. (C) 2008 Elsevier Ltd. All rights reserved.