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Biomedical subjects

H Yildiz

Publications and source records attributed to H Yildiz.

13 recordsLinked to original sources
PubMed2006

Global attention to Turkey due to desertification.

Desertification has recognized as an environmental problem by many international organizations such as UN, NATO and FAO. Desertification in Turkey is generally caused by incorrect land use, excessive grazing, forest fires, urbanization, industry, genetic erosion, soil erosion, salinization, and uncontrolled wild type plants picking. Due to anthropogenic destruction of forest, steppe flora gradually became dominant in Anatolia. In terms of biodiversity, Turkey has a significant importance in Europe and Middle East. Nine thousands plant species naturally grown in Turkey, one third of them are endemic. Also, endemic species of vertebrates, thrive in the lakes and marshy areas. The studies of modelling simulation of vegetation on the effects of Mediterranean climate during the Roman Classical period by using vegetation history showed that, in 2000 years BP, Mediterranean countries were more humid than today. Turkey is a special place on the global concern in terms of desertification because of biodiversity, agricultural potential, high population, social and economical structure, topographical factors and strategic regional location. Communication among scientists, decision makers and international non-profit organizations must be improved.

Climate↗
PubMed2006

Percutaneous placement of central venous catheters: comparing the anatomical landmark method with the radiologically guided technique for central venous catheterization through the internal jugular vein in emergent hemodialysis patients.

PURPOSE: To compare the success and immediate complication rates of the anatomical landmark method (group 1) and the radiologically (combined real-time ultrasound and fluoroscopy) guided technique (group 2) in the placement of central venous catheters in emergent hemodialysis patients. MATERIAL AND METHODS: The study was performed prospectively in a randomized manner. The success and immediate complication rates of radiologically guided placement of central venous access catheters through the internal jugular vein (n=40) were compared with those of the anatomical landmark method (n=40). The success of placement, the complications, the number of passes required, and whether a single or double-wall puncture occurred were also noted and compared. RESULTS: The groups were comparable in age and sex. The indication for catheter placement was hemodialysis access in all patients. Catheter placement was successful in all patients in group 2 and unsuccessful in 1 (2.5%) patient in group 1. All catheters functioned adequately and immediately after the placement (0% initial failure rate) in group 2, but 3 catheters (7.5% initial failure rate) were non-functional just after placement in group 1. The total number of needle passes, double venous wall puncture, and complication rate were significantly lower in group 2. CONCLUSION: Percutaneous central venous catheterization via the internal jugular vein can be performed by interventional radiologists with better technical success rates and lower immediate complications. In conclusion, central venous catheterization for emergent dialysis should be performed under both real-time ultrasound and fluoroscopic guidance.

Adolescent↗
PubMed2006

Pathological effects of Arcobacter cryaerophilus infection in rainbow trout (Oncorhynchus mykiss Walbaum).

Arcobacter cryaerophilus was isolated from naturally infected rainbow trout (Oncorhynchus mykiss Walbaum), and its pathogenicity was tested by intramuscular injection into 40 healthy 1-year-old rainbow trout at 16 degrees C. The lethal dosage of 50% end point (LD50) for A. cryaerophilus was calculated 2.25 x 10(4) viable cells. Experimental infection caused deaths with gross clinical abnormalities such as degenerated opercula and gills, liver damage, haemorrhagic kidney and serous fluid in swollen intestines. The counts of A. cryaerophilus in kidney, liver and gills of experimentally infected fish ranged from 1.59 x 10(10) colony forming units (cfu)/g to 7.41 x 10(12) cfu/g. The means of erythrocyte (RBC) count, haematocrit level, serum cholesterol, triglyceride, albumin and total protein concentrations in the blood of the experimentally infected rainbow trout group were significantly lower than in the healthy fish. Leukocyte (WBC) counts of the experimentally infected rainbow trout were significantly higher than those of healthy fish. The present work shows that the selected blood characteristics may be good indicators of response to infections in rainbow trout.

Animals↗
PubMed2005

Effects of different management factors on broiler performance and incidence of tibial dyschondroplasia.

(1) This study was to determine the effects of two lighting programmes (continuous--24L:0D or intermittent--12L:3(1L:3D)), two feeding programmes (continuous--ad libitum or meal Jeeding--3 h feed:3 h deprivation x 4 times per d) and two ascorbic acid (AA) supplementations (0 or 150 mg/l in water) on broiler performance and incidence of tibial dyschondroplasia (TD). (2) One-day-old male commercial (Ross PM3) broiler chicks (1600) were used. The chicks were randomly divided into 8 treatment groups (2 x 2 x 2) and their replicates (2) replicates per treatment). (3) Intermittent lighting increased body weight and improved feed conversion. Body weight of broilers was decreased by meal feeding. AA supplementation had no significant effect on the body weight and feed conversion ratio. There was no lighting x feeding x supplemental AA interaction for body weight, feed conversion ratio, mortality rate and carcase weight. (4) Supplemental AA improved the cortical thickness of tibiotarsus and decreased the incidence of TD. (5) It was concluded that the application of intermittent lighting in combination with supplementation of 150 mg/l AA is a useful method to reduce TD in broilers without loss of performance.

Animal Feed↗
PubMed2005

Magnetic resonance imaging and diffusion-weighted imaging in methylmalonic acidemia.

Methylmalonic acidemia (MMA) is an inborn disorder of amino acid metabolism, often presenting with neurological symptoms. We present the results of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) of the brain in a 16-month-old male patient with classic neurological and laboratory findings for MMA. MRI demonstrated the hyperintensity within globi pallidi both on T2-weighted image and DWI during the acute episode of metabolic acidosis.

Acidosis↗
PubMed2003

A study on the morphological structure of syrinx in ostriches (Struthio camelus).

The aim of this study was to investigate the topographical, anatomical and histological characteristics of syrinx in five ostriches. It was observed that the syrinx in the ostrich was tracheobronchial type and was composed of three different cartilage groups, namely tympanum, cartilagines (cartt.) tracheosyringeales and cartt. bronchosyringeales. Tympanum and cartt. tracheosyringeales were formed from three and four cartilage rings, respectively, while cartt. bronchosyringeales was formed from three C-shaped cartilage rings. The pessulus did not contain any ossified or cartilaginous tissues and was made up of a double folded mucous membrane extending dorsoventrally from median walls of bronchus primarius into the cavum syringis.

Animals↗
PubMed2001

A mathematical model of the ascending colon of the horse.

In this study we present a geometric model of the ascending colon of the horse, especially the left ventral colon and the right ventral colon, the left dorsal colon and the right dorsal colon and the pelvic flexure. We also present a mathematical model of the cross sections of these ascending colon parts with the exceptions of the pelvic flexure. We show that these cross-sections correspond to the closed algebraic curves known as epitrochoid.

Animals↗
PubMed1998

Composite hip prosthesis design. II. Simulation.

An investigation was performed to study the mechanical performance of fiber-reinforced composite hip prostheses. In Part I of the study, a three-dimensional finite element code was developed for analyzing a composite hip prosthesis in a femur. The material properties of the composite were treated as anisotropic and inhomogeneous while the properties of the femoral bone were treated as anisotropic and homogeneous. All the materials were assumed to behave linear-elastically. Thermoplastic graphite/PEEK material was selected for the study. No slippage was assumed at the interface between the implant and the surrounding femoral bone. In Part II, numerical simulations were performed using the code to study the performance of a composite prosthesis in the femur. The stress/strain distributions, micromotions, and strain energy density of the surrounding femoral bone were evaluated and found to be related to initial fixation and long-term stability of the prosthesis in the femur. Numerous fiber orientations were studied, and the results of the calculations were compared with those generated from a prosthesis made of cobalt chrome and Ti-6Al-4V titanium alloys. Based on the analysis, it was shown that compared to conventional metallic implants more favorable stresses and deformations could be generated in the femur using composite implants. In addition, by changing fiber orientations according to femoral loads, a composite implant could be designed specifically for the left or the right femur.

Computer Simulation↗
PubMed1998

Composite hip prosthesis design. I. Analysis.

An investigation was performed to study the mechanical performance of fiber-reinforced composite hip prostheses in a femur. The main objective of the study was to evaluate the effect of fiber orientation of a composite femoral implant on the response of the surrounding femoral bone. A three-dimensional finite element analysis was developed for analyzing a composite implant in the femur. A three-dimensional composite element was proposed to take into account ply drop-off due to a change of cross-section of the composite implant. The element could accommodate multidirectional layers and tapered composites. The material properties of the composite were treated as anisotropic and inhomogeneous while the properties of femoral bone were treated as anisotropic and homogenous. All the materials were assumed to behave linear-elastically. The thermoplastic graphite/PEEK material system was selected for the study. In this presentation, as the first part of the study, the development of the finite element analysis will be described. Numerical calculations were generated and compared with existing data and numerical results available from studies related to metal hip prostheses in the literature. Experiments on the composite hip implants were also conducted for further verification of the analysis and the computer simulations. In Part II, using the finite element code, an extensive study was performed to evaluate the stress/strain distributions, micromotions, and strain-energy density of the surrounding femoral bone, which have been related to initial fixation and long-term stability of the prosthesis in a femoral bone. Numerous fiber orientations were studied, and results of the calculations were compared with those generated by the prosthesis made of cobalt alloy and titanium alloy.

Hip Prosthesis↗
PubMed1996

An investigation on plasma progesterone levels during pregnancy and at parturition in the Ivesi sheep.

In this study, plasma progesterone concentrations in a total of 45 Ivesi sheep were investigated during pregnancy and at parturition. Blood samples were collected from all the sheep studied every 20 days commencing on the 30th day of pregnancy. Plasma progesterone levels were determined by radioimmunoassay. During the second half of the pregnancy, progesterone concentrations in the sheep giving birth to one, two and three lambs were 2.02 +/- 0.08 ng/ml, 3.24 +/- 1.18 ng/ml and 4.90 +/- 0.85 ng/ml, respectively. There was no significant variation in progesterone levels between sheep with male and female offspring. At parturition, plasma progesterone concentrations did not differ significantly between the animals. The present results indicate that plasma progesterone levels could be used not only to determine the pregnancy status of the animal but also to predict the number of fetuses after the second half of the pregnancy.

Animals↗
PubMedDate not supplied

Distal muscular dystrophy of the Miyoshi type.

OBJECTIVE: Miyoshi myopathy is an autosomal recessive muscular dystrophy. It is characterized by distal muscle involvement, especially the gastrocnemius and soleus. The disease starts with weakness and atrophy of the calves. MATERIAL AND METHODS: Here we report on 2 patients, brother and sister, from a Turkish family. Onset of the disease was at the age of 20 and 26 years of age, respectively. In both siblings, there was an early and predominant involvement of the distal muscles of the lower limbs. Creatine kinase activity was elevated 50- to 100-fold above normal values. RESULTS: Electromyography revealed a myopathic pattern. Histology of the biceps muscles indicated some myopathic changes consistent with muscular dystrophy. Occurrence in only these 2 siblings with no other family members was indicative of an autosomal recessive inheritance. CONCLUSIONS: We describe the distinctive clinical features in 2 siblings of a Turkish family with MM as differential diagnosis and histological change.

Adult↗
PubMedDate not supplied

Table-moving contrast-enhanced magnetic resonance angiography in the evaluation of lower extremity peripheral arterial bypass grafts.

The aim of this study was to investigate the utility of table-moving contrast-enhanced three-dimensional MR angiography in the evaluation of lower extremity peripheral arterial bypass grafts. Twenty-two lower extremity peripheral arterial grafts (13 autologous saphenous vein, 7 polytetrafluoroethylene and 2 Dacron) in 18 patients were evaluated. Preoperative diagnosis were occlusive arterial segments in 14 cases, 4 aneurysms in 2 cases (3 aneurysms in one case) and traumatic femoral artery injury in 2 cases. 1.5T superconductive magnet was used with torso-phase and whole body coil system on MRI examinations. Lower extremity peripheral arterial grafts were evaluated and anastomosis sites were classified into five groups as normal, insignificant stenosis (< 50%), significant stenosis (> 50%), occlusion and ectatic or aneurysmatic appearance. Contrast-enhanced MR angiography imaging of 66 segments of 22 graft patients were of high quality. No difficulties were confronted in the radiological evaluation of peripheral bypass grafts. Graft stenosis as detected in five grafts. Stenotic segments were at the proximal (n = 4) and distal (n = 3) anastomosis sites. Total occlusion was shown in three grafts. Ectasia or aneurysm was seen in only one graft. In lower extremity peripheral bypass graft patients, table-moving contrast enhanced MR angiography can be used in the evaluation and follow-up of the vascular lesions.

Arterial Occlusive Diseases↗