Showing papers by "Istanbul University published in 1997"

Mutations in the chloride channel gene, CLCNKB, cause Bartter's syndrome type III

Abstract: Analysis of patients with inherited hypokalaemic alkalosis resulting from salt-wasting has proved fertile ground for identification of essential elements of renal salt homeostasis and blood-pressure regulation. We now demonstrate linkage of this phenotype to a segment of chromosome 1 containing the gene encoding a renal chloride channel, CLCNKB. Examination of this gene reveals loss-of-function mutations that impair renal chloride reabsorption in the thick ascending limb of Henle's loop. Mutations in seventeen kindreds have been identified, and they include large deletions and nonsense and missense mutations. Some of the deletions are shown to have arisen by unequal crossing over between CLCNKB and the nearby related gene, CLCNKA. Patients who harbour CLCNKB mutations are characterized by hypokalaemic alkalosis with salt-wasting, low blood pressure, normal magnesium and hyper- or normocalciuria; they define a distinct subset of patients with Bartter's syndrome in whom nephrocalcinosis is absent. These findings demonstrate the critical role of CLCNKB in renal salt reabsorption and blood-pressure homeostasis, and demonstrate the potential role of specific CLCNKB antagonists as diuretic antihypertensive agents.

Induction of Long-Term Glycemic Control in Newly Diagnosed Type 2 Diabetic Patients by Transient Intensive Insulin Treatment

Abstract: OBJECTIVE Type 2 diabetes is a slowly progressive disease, in which the gradual deterioration of glucose tolerance is associated with the progressive decrease in β-cell function. Hyperglycemia per se has deleterious effects on both beta-cell function and insulin action, which are partially reversible by the short-term control of blood glucose levels. We hypothesized that the induction of euglycemia, using intensive insulin therapy at the time of clinical diagnosis, could lead to a significant improvement in insulin secretion and action and thus alter the clinical course of the disease. RESEARCH DESIGN AND METHODS Thirteen newly diagnosed diet-unresponsive type 2 diabetic patients were treated with continuous subcutaneous insulin infusion (CSII) for 2 weeks and followed longitudinally while being treated with diet alone. RESULTS Four patients were considered therapeutic failures since CSII failed to induce euglycemia ( n = 1) or glucose control deteriorated within 6 months after CSII ( n = 3). The remaining nine patients were maintained on diet alone with adequate control from 9 to > 50 months (median ± SE, 26 ± 4.8 months). In five patients, glycemic control deteriorated after 9–36 months, but a repeat 2-week CSII treatment reestablished control in four patients. One of these patients underwent a third CSII treatment 13 months later. At the time this article was written, six patients of the initial group were still controlled without medication 16–59 months (median ± SE, 45.5 ± 6.6 months) after the initiation of treatment. Body weight remained unchanged in all patients. CONCLUSIONS These findings suggest that in a significant proportion of type 2 diabetic patients who fail to respond to dietary measures, short-term intensive insulin treatment can effectively establish responsiveness, allowing long-term glycemic control without medication. Further studies are required to establish whether simpler treatment regimens could be equally effective. If the hypothesis offered here finds support, present approaches to the management of newly diagnosed type 2 diabetes may need to be revised.

Thermal History of Sedimentary Basins

Abstract: Geoscientists have always been interested in temperature values, as the crucial role of temperature in various geological, geochemical, and geophysical phenomena was recognized relatively early However, this interest was long limited to aspects such as temperature distribution in the earth’s crust and mantle, melting temperatures of different rocks, equilibrium temperatures of various metamorphic mineral assemblages, and temperature dependency of some geophysical parameters Almost all of these are related to thermal conditions in the deeper parts of the earths crust Low temperature fields at shallow depth have been of less concern It is interesting to recognize that all these studies sought to define either the present distribution of temperature or the maximum temperature reached at some time in the geological past In other words, temperature distribution as a steady state case was the subject of interest

Azathioprine in Behçet's syndrome. Effects on long‐term prognosis

Abstract: Objective. To assess the effect of azathioprine (AZA) treatment on long-term prognosis in Behcet's syndrome. Methods. Patients (all male) who took part in a double-blind, placebo-controlled trial of AZA a mean ± SD of 94 ± 10 months previously were reevaluated. Results. The emergence of blindness (log rank χ2 = 5.6, P = 0.02) and a 2-line drop in the visual acuity of the right eye (log rank χ2 = 5.9, P = 0.015) occurred significantly more frequently among the patients originally allocated to the placebo group compared with patients who originally received AZA, despite posttrial treatment for patients in both groups when needed. There was also a trend toward more frequent occurrence of extraocular complications in the placebo group. The beneficial effect of AZA was especially pronounced among patients who had eye involvement of short duration prior to their entry into the trial. Conclusion. Early treatment with AZA tends to favorably affect the long-term prognosis of Behcet's syndrome.

Neural network applications in business: a review and analysis of the literature (1988-95)

Abstract: A survey of journal articles on neural network business applications published between 1988 and 1995 indicates that an increasing amount of neural network research is being conducted for a diverse range of business activities. The classification of literature by (1) year of publication, (2) application area, (3) problem domain, (4) decision process phase, (5) level of management, (6) level of task interdependence, (7) means of development, (8) corporate/academic interaction in development, (9) technology integration, (10) comparative study, (11) major contribution, and (12) journal provides some insights into the trends in neural networks research. The implications for neural networks developers/researchers and suggestions on future research areas are discussed.

Comparison of volume controlled with pressure controlled ventilation during one-lung anaesthesia

Abstract: Pressure controlled ventilation (PCV) is an alternative mode of ventilation which is used widely in severe respiratory failure. In this study, PCV was used for one-lung anaesthesia and its effects on airway pressures, arterial oxygenation and haemodynamic state were compared with volume controlled ventilation (VCV). We studied 48 patients undergoing thoracotomy. After two-lung ventilation with VCV, patients were allocated randomly to one of two groups. In the first group (n = 24), one-lung ventilation was started by VCV and the ventilation mode was then switched to PCV. Ventilation modes were performed in the opposite order in the second group (n = 24). We observed that peak airway pressure (P = 0.000001), plateau pressure (P = 0.01) and pulmonary shunt (P = 0.03) were significantly higher during VCV, whereas arterial oxygen tension (P = 0.02) was significantly higher during PCV. Peak airway pressure (Paw) decreased consistently during PCV in every patient and the percentage reduction in Paw was 4-35% (mean 16.1 (SD 8.4) %). Arterial oxygen tension increased in 31 patients using PCV and the improvement in arterial oxygenation during PCV correlated inversely with preoperative respiratory function tests. We conclude that PCV appeared to be an alternative to VCV in patients requiring one-lung anaesthesia and may be superior to VCV in patients with respiratory disease.

Vasculitis in familial Mediterranean fever.

Abstract: Objective To evaluate the frequency of vasculitis, mainly in the forms of Henoch-Schonlein purpura and polyarteritis nodosa (PAN), and to investigate the presence of occult blood in the first stool specimens after an abdominal attack in Turkish patients with familial Mediterranean fever (FMF). Methods Review of the charts of 207 patients with FMF seen between 1983 and 1993 with respect to clinical vasculitis. A prospective study designed to test the presence of occult blood in the first stool specimens obtained after abdominal attack and at least one week later in 36 patients with FMF compared with healthy and diseased controls. Results There were 15 patients with Henoch-Schonlein purpura (7%), 2 with definite and one with probable PAN (1%), one of whom developed perirenal hematoma. The diagnosis of FMF was made after the onset of Henoch-Schonlein purpura in 9 and subsequent to the development of PAN in one patient. Occult blood was positive in the first stool specimens obtained after an attack in 17 of the 36 patients with FMF (47%), a finding not reported previously. Conclusion Vasculitis seems to be an important but not a widely recognized feature of FMF.

The Relationship Between Clinical Periodontal Status and Insulin-Dependent Diabetes Mellitus. Results After 5 Years

Abstract: The clinical periodontal status of 44 insulin-dependent diabetic children and adolescents and 20 healthy control subjects was compared for a period of approximately 5 years. Fasting blood glucose, fmctosamine, and glycosylated hemoglobin (HbA1) values were determined at baseline and 5 years later. The differences in the clinical and laboratory parameters were compared during the study period. The differences between the two groups were also evaluated. The only statistically significant difference observed in the diabetic group was clinical attachment loss (CAL). The CAL was statistically significantly higher in the diabetic group compared to the controls, and a statistically significant positive correlation was observed between the duration of diabetes and CAL. Fmctosamine was also correlated with the gingival index in the diabetic group while there was no correlation in the controls. It may be concluded that diabetes modifies the clinical status of the periodontal tissues and increases clinical attachmen...

Time-frequency analysis reveals multiple functional components during oddball P300.

Abstract: A time-frequency decomposition was applied to rare target and frequent non-target event-related potentials (ERPs) elicited in an oddball condition to assess whether multiple functional components occur in the P300 latency range. The wavelet transform (WT) was used because it allows capture of simultaneous or partly overlapping components in ERPs without loosing their temporal relationships. The application of a four-octave quadratic B-spline wavelet transform at the level of single-sweep data allowed us to obtain new information and revealed the presence of separate events during P300 development. Several delta, theta, and alpha frequency components in the P300 latency range differed between target and non-target processing. These findings indicate that P300 is composed of multiple functional components and that the WT method is of use for the study of P300 functional correlates more precisely.

Oxygen free radicals impair wound healing in ischemic rat skin.

Abstract: Oxygen free radicals are produced and play an important role in ischemic injury. We therefore wished to investigate the role of free radicals on ischemic skin wound healing. For this purpose, H-shaped flaps, where the test ischemic wound is the horizontal line in the H, were created on the dorsum of the rat. To inhibit the probable hazards of free radicals, allopurinol and superoxide dismutase (SOD) were given to the animals. Most of the studied wound-healing parameters were impaired in the ischemic group. In the allopurinol-treated group, breaking strength was increased by 52% by day 7 and by 109% by day 14 (p < 0.0002 and p < 0.001), and in the SOD-treated group the increase was 69% both by days 7 and 14 of healing when compared with the ischemic control group (p < 0.003 and p < 0.002). Hydroxyproline content was increased 75% with allopurinol and 113% with SOD in the wound by day 7 (p < 0.03 and p < 0.001 respectively). SOD treatment caused a significant decrease in wound edema by day 7 of healing (p < 0.05). Histopathological evaluation revealed that in the SOD- and allopurinol-treated groups, the amount of collagen and its organization were more prominent when compared with the ischemic controls. These results show that oxygen free radicals play an important role in the failure of ischemic wound healing, and antioxidants partly improve the healing in ischemic skin wounds.

Effect of transient focal ischemia on blood-brain barrier permeability in the rat : correlation to cell injury

Abstract: Prolonged ischemia is known to damage the blood-brain barrier, causing an increase in vascular permeability to proteins. We studied the time course of extravasation of endogenous albumin in rats after 1 and 2 h of middle cerebral artery (MCA) occlusion followed by 6, 12, and 24 h of recirculation. In a separate group of rats that had undergone 1 h of MCA occlusion and 6 h of recirculation, influx of [14C]aminoisobutyric acid (AIB) from blood to brain was also measured. After 1 h of occlusion followed by 6 h of recirculation, neuronal damage was evident in caudoputamen, but there were no signs of blood-brain barrier leakage to either AIB or albumin. At 12 h, the caudoputamen contained extravasated albumin, and at 24 h extravasation was extended to the somatosensory cortex. Animals subjected to 2 h of MCA occlusion showed albumin extravasation in caudoputamen already at 6 h of recirculation, and at 12 and 24 h albumin was abundant in the major part of the right hemisphere. This study suggests that damage to neurons precedes leakage of the blood-brain barrier. Even a relatively short period of ischemia such as 1 h will result in markedly increased vascular permeability. However, a longer transient ischemic insult disrupts the blood-brain barrier earlier than a shorter one.

Origin of the Sea of Marmara as Deduced from Neogene to Quaternary Paleogeographic Evolution of its Frame

Abstract: The Sea of Marmara Basin (SMB) is connected to the fully marine Mediterranean by the Dardanelles strait and to the brackish Black Sea by the Thracian Bosporus. This linkage to two different marine realms with contrasting water chemistry has been a prime control on the sedimentary history of the SMB, which in turn was controlled by its tectonics. Isolation from any of these realms resulted in drastic changes in its paleoceanographic conditions and made it a part either of the global ocean system or of a brackish-marine environment, depending on the realm from which the connection was severed. The SMB represents the inundated part of the northwestern Anatolian graben system that resulted from the interaction between the North Anatolian fault (NAF) zone and the present N-S extensional tectonic regime of the Aegean. The geologic history of this basin began during the late Serravallian when the NAF was initiated. The first inundation of the basin coincided in both time and space with this initiation. The invad...

Graft copolymerization of acrylic acid on cellulose: Reaction kinetics of copolymerization

Abstract: Acrylic acid (AA) was grafted to cellulose by using ceric ammonium nitrate (CAN) initiator in aqueous nitric acid solution at 30, 50, 70, and 907C during reaction periods of 30 to 180 minutes. About 45% of the AA was polymerized at 907C after 180 minutes. The grafted polymer and homopolymer were isolated by acetone from the reaction mixture, dried, and subjected to Soxhlet extraction with dioxane to separate the homopolymer, poly(acrylic acid), from the graft copolymer. The water absorption capacities and grafting values of grafted cellulose were also determined. The maximum grafting yield was obtained at 307C. It was also observed that polyacrylic acid-grafted cellulose produced at 307C had the highest water retention capacity. The time depen- dence of AA conversion allowed calculation of first-order reaction rate constants. These rate constants were then used to determine apparent activation energies. q 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 929-934, 1997

Furnace smelting and extractive metallurgy of red mud : Recovery of TiO2, Al2O3 and pig iron

Abstract: Turkish red mud (bauxite waste) has been mixed with dolomite and coke, pelletized and sintered at 1100°C, and finally smelted at 1550°C to produce pig iron and a slag. The slag was leached with 30% H 2 SO 4 at 90°C. The leachate was diluted, ferric iron was reduced with SO 2 , and extracted with 5% D2EHPA solution in kerosene. Silica and Al 2 O 3 were recovered from the remaining aqueous solution, while the organic extract was stripped with 10% Na 2 CO 3 solution, finally hydrolysed and calcined to produce pigment-grade TiO 2 . The titanium recovery efficiency on the basis of slag weight was 84.7%. The extractive separation of titanium from both valencies of iron was investigated as a function of pH and time. A stoichiometric flowsheet for the whole process has been developed.

Life story of Dr. Hulusi Behçet.

Abstract: Dr. Hulusi Behcet was born on February 20, 1889 in Istanbul. He graduated from Gulhane Military Medical Academy in 1910 and then he specialized in Dermatology and Venereal Diseases. He served in the Edirne Military Hospital between 1914-1918 and then went to Budapest and Berlin to improve his knowledge. In 1923, he started at the Istanbul Medical Faculty as an academic staff and with university reform in 1933, he was appointed as a professor to Department of Dermatology and Venereal Diseases and continued his career there until his death in 1948. Three patients whom he had consulted for years and who shared similar symptoms made him suspect a new disease and a viral etiology which may play a role in the appearance of this disease. After several discussions and publications, medical literature had accepted Behcet's Disease as a special entity. Dr. Behcet published a total of 196 articles, 53 of which were published in prestigious international journals.

Traumatic spinal cord injuries in Southeast Turkey: an epidemiological study

Abstract: In 1994, a retrospective study of new cases of traumatic Spinal Cord Injury (SCI) was conducted in all the hospitals in Southeast Turkey: 75 new traumatic SCI were identified. The estimated annual incidence was 16.9 per million population. The male/female ratio was 5.8/1. The mean age was 31.3, being 31.25 for male patients and 31.36 for female patients. 70.7% of all patients were under the age of 40. The major causes of SCI were falls (37.3%) and gunshot wounds (29.3%), followed by car accidents (25.3%), and stab wounds (1.3%). Thirty one patients (41.3%) were tetraplegic and 44 (58.7%) paraplegic. In tetraplegic patients the commonest level was C5, in those with paraplegia L1. The commonest associated injury was head trauma followed by fractures of the extremity(ies). Severe head trauma, being a major cause of death, may have obscured the actual incidence of SCI. Most of gunshot injured SCI patients were young soldiers fighting against the rebels. As there was no available data for the rebels with SCI, the actual incidence of SCI in Southeast (SE)Turkey should be higher than that found in this study.

Relationship between retinal lesions and axial length, age and sex in high myopia.

Abstract: We analysed the relationship between central and peripheral retinal lesions and axial length (AL), patient's age and sex with myopia greater than 6 diopters. A total of 212 eyes of 109 patients with high myopia underwent detailed funduscopy and A-scan ultrasonography. AL was measured, and central and peripheral retinal lesions were noted. Results were analysed using Student's t-test. Sixty-one patients (118 eyes) were female and 48 (94 eyes) male. Mean age was 31.00 +/- 13.67 years, and mean AL was 28.31 +/- 2.02 mm. Chorioretinal atrophy, Fuchs' spot, posterior staphyloma and posterior vitreous detachment increased significantly with AL and age. Fuchs' spot was more common in females. White-without-pressure (WWP) was inversely correlated with AL and age, and was more common in males. The high frequency of WWP in younger patients and moderate AL suggests that these lesions result from vitreoretinal tractions. Lattice degeneration was also a frequent finding in high myopia, and tended to increase with AL and age, though without reaching statistical significance.