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Biomedical subjects

G Aktan

Publications and source records attributed to G Aktan.

9 recordsLinked to original sources
PubMed2003

Wolfram (DIDMOAD) syndrome: a multidisciplinary clinical study in nine Turkish patients and review of the literature.

AIM: To study Wolfram syndrome (WFS) with multidisciplinary consultations and compare the results with the literature. METHODS: Nine patients fulfilled the ascertainment criteria of WFS (insulin-dependent diabetes mellitus and optic atrophy). All patients were evaluated by the departments of paediatrics, ophthalmology, audiology, urology and medical biology. RESULTS: The earliest manifestation of WFS was insulin-dependent diabetes mellitus (at a median age of 6.9 y), followed by optic atrophy (8.9 y), diabetes insipidus (10.2 y) and deafness (10.5 y). Short stature was found in five cases, delayed puberty in two cases and hypergonadotropic hypogonadism in one case. Audiography disclosed hearing loss at high frequency in all patients (100%), but only five patients had clinical subjective hearing problems. Intravenous pyelography revealed hydroureteronephrosis in eight patients. Urodynamics revealed a normal bladder in only one patient. Three patients had a low-capacity, low-compliance bladder, detrusor external sphincteric dyssynergia and emptying problem, while five had an atonic bladder. Ocular findings were optic atrophy, low visual acuity and colour vision defects. Visual field tests revealed concentric and/or peripheral diminution in five patients. Visual evoked potentials were abnormal (reduced amplitude to both flash and pattern stimulation) in seven patients. Cranial magnetic resonance imaging showed mild or moderate atrophy of the optic nerves, chiasm, cerebellum, basal ganglia and brainstem in six patients; there was a partially empty sella in one case. There was no evidence of mitochondrial tRNA(Leu) (UUR) A to G (nucleotide 3243) mutation. CONCLUSION: Wolfram syndrome should be evaluated in a multidisciplinary manner. Some specific and dynamic tests are necessary to make a more precise estimate of the prevalence and median age of the components of WFS. Short stature is a common feature in WFS. Hypogonadism may be hypogonadotropic or hypergonadotropic. Bladder dysfunction does not always present as a large atonic bladder in WFS. A low-capacity, high-pressure bladder with sphincteric dyssynergia is also common.

Adolescent↗
PubMed2002

The role of Na,K-ATPase in human sperm motility.

A fourth Na,K-ATPase alpha isoform, which was found to be abundant in testes, was proved to be a catalytical subunit of the enzyme. Recently, it has been shown that the alpha 4 isoform along with alpha 1 is expressed in the midpiece of the flagellum of mature rat sperm and the inhibition of alpha 4 with ouabain led to sperm immotility. In this study, sperm from 135 males with normal semen profile and 50 males with oligoasthenospermia were treated with 10-5 and 10-2 M ouabain solutions to inhibit alpha 4, and alpha 4 plus alpha 1 isoforms, respectively. In males with normal semen profile, sperm motility has been demonstrated to decrease with time to almost the same level with both ouabain solutions. In oligoasthenospermic males motility was also found almost completely lost. These observations showed us that the alpha 4 isoform may be held responsible for human sperm motility. When sperm plasma membrane Na,K-ATPase activity was assayed for both normal and oligoasthenospermic males, a significant decrease in enzyme activity of males with oligoasthenospermia was observed (p < 0.05). In our recent study, sperm motility was found decreased by treatment with peroxynitrite (ONOO-). To investigate the effect of ONOO- on sperm Na,K-ATPase activity, sperm plasma membranes were treated with 100 microM ONOO- and plasma membrane Na,K-ATPase activity was observed to be significantly decreased (p < 0.05). Although total sulfhydryl (SH) content of sperm plasma membrane was also found significantly lower, no correlation was found between Na,K-ATPase activity and SH content.

Adult↗
PubMed1997

Rhombencephalosynapsis associated with hand anomalies.

A case of rhombencephalosynapsis, a very rare disorder characterized by agenesis or hypogenesis of the cerebellar vermis and fusion of the cerebellar hemispheres, is reported with magnetic resonance imaging features. Radiographs showed anomalies in both hands; namely phalangeal hypoplasia and occult polydactyly in the right hand and syndactyly in the left, previously unreported in association with this disorder.

Abnormalities, Multiple↗
PubMed1996

Clinical and magnetic resonance imaging features of L-2-hydroxyglutaric acidemia: report of three cases in comparison with Canavan disease.

We report three cases of L-2-hydroxyglutaric acidemia and three cases of Canavan disease. The L-2-hydroxyglutaric acidemia cases are the first biochemically proven Turkish cases. Magnetic resonance imaging findings in the cases and similarities between the two diseases are emphasized. Both diseases are characterized by predominant subcortical white-matter involvement and dentate nuclei lesions with variable basal ganglia involvement. Canavan disease differs from L-2-hydroxyglutaric acidemia by the presence of typical brainstem involvement.

Canavan Disease↗
PubMed1996

Topical cyclosporine as a possible new antimetabolite in trabeculectomy.

BACKGROUND AND OBJECTIVE: The authors conducted a randomized, prospective, and controlled clinical and transmission electron microscopic study to investigate the possible role of cyclosporine in trabeculectomy as an antimetabolite agent. PATIENTS AND METHODS: Twelve patients underwent trabeculectomy with topical cyclosporine and another 12 patients had trabeculectomy without cyclosporine. RESULTS: There was a statistically significant decrease in the postoperative intraocular pressure (P < .05) and in the number of medications needed postoperatively (P < .01) in the cyclosporine group. There were no significant complications in either group. Transmission electron microscopic examinations of the excised trabecular scleral tissue showed that cyclosporine caused inhibition of fibroblasts and led to a disruption in collagen organization at the level of the surgical dissection. Middle scleral layers were generally not affected except in some cyclosporine-treated eyes, which showed only a mild cytopathic effect. CONCLUSION: This study showed that topical cyclosporine was safe and effective for use as an antimetabolite in trabeculectomy. Further studies are needed to substantiate the adjuvant role of cyclosporine in glaucoma filtering operations.

Administration, Topical↗
PubMed1995

Medical and surgical aspects of congenital glaucoma.

During the years 1977-1986, 338 patients at the University Eye Clinic were diagnosed as having congenital glaucoma. This paper presents our experience of the management of 88 of these patients (161 eyes) who had a follow-up of at least 3 years. Medical therapy alone reduced the intraocular pressure to less than 21 mmHg in 17 eyes (11.8%) in the short-term and in 14 eyes (9.7%) in the long-term. Surgical intervention in 127 eyes (goniotomy: 9 eyes; trabeculotomy: 3 eyes; peripheral iridencleisis: 4 eyes; Elliott trephine; 23 eyes; trabeculectomy: 88 eyes), resulted in an immediate normalization of intraocular pressure in 98 eyes (77%, reducing to 66% at the final examination). Trabeculectomy normalized the intraocular pressure in 84% of eyes in the short-term and 76% in the long-term. Trabeculectomy is recommended as the surgical management of choice in congenital glaucoma in societies where presentation is late, or where individual surgeons may not be conversant with goniotomy.

Acetazolamide↗
PubMedDate not supplied

Trabeculectomy with mitomycin C: an electron microscopic and clinical study.

A prospective and randomized clinical trial was conducted to investigate the pressure-lowering effect of mitomycin C-aided trabeculectomy in the Turkish population. The scleral tissues excised during the operation were examined by light and electron microscopy. The study population consisted of 26 patients undergoing mitomycin C-aided trabeculectomy and another 26 patients subjected to trabeculectomy without mitomycin C serving as controls. The treatment groups consisted of primary open-angle and closed-angle glaucomas, congenital glaucomas, various types of secondary glaucomas and prior failed trabeculectomies. The decrease in IOP was more marked (P < 0.01) and the number of additional medications needed post-operatively was less in the mitomycin C group (P < 0.01). There were no serious complications except for transient hypotony in one mitomycin-treated eye. Transmission electron microscopic examinations showed differences between the control and mitomycin applied trabecular blocks. At the scleral dissection plane where mitomycin was applied, collagen fibrils were frayed with a loss of proteoglycan cross-links. Fibroblasts demonstrated pyknotic nuclei and loss of cell processes. In the control group, active fibroblasts and regular collagen structure were observed at this level. The middle and inner scleral layers were generally unaffected except for minor changes in some of the mitomycin-treated eyes. Our study showed mitomycin C to be safe and effective as adjunct to trabeculectomy in both primary open-angle, primary angle-closure, various secondary glaucomas and prior failed trabeculectomies. Transmission electron microscopic examinations of excised blocks showed disruption in collagen organization and cytopathic effects to fibroblasts. Mitomycin seemed to affect the proteoglycan cross-links between collagen fibrils after its application.

Adult↗
PubMedDate not supplied

A comparative clinical trial of mitomycin C and cyclosporin A in trabeculectomy.

This prospective, randomized clinical trial assessed the effects of mitomycin C and cyclosporin A used as antimetabolites in trabeculectomy on the post-operative IOP and success rate. Eighty-six consecutive patients were randomly allocated to three treatment groups. There were 30 patients in the mitomycin C group, 28 in the cyclosporin A group and 28 in the control group. The follow-up periods were different for the three groups and ranged from 6 to 30 months. The treatment groups consisted of primary open-angle glaucoma, closed-angle glaucoma, various secondary glaucomas and prior failed trabeculectomy. There were no significant differences pre-operatively with respect to IOP and number of medications used (p > 0.05). Postoperative IOP was considered to be successfully reduced when it was reduced by more than 25% from baseline or when it was lower than 20 mmHg. According to these criteria, IOP was under control in 90% of the mitomycin C treated eyes, 85.7% of cyclosporin A treated eyes and 71.4% of the control eyes. Postoperatively there was a significant decrease in IOP (p < 0.01) and in the number of medications need to control IOP (p < 0.01) in the mitomycin C and cyclosporin A groups. Post-operative IOP and number of medications in the mitomycin C and cyclosporin A group were similar. Complications encountered in the three groups were similar. There were no serious complications like hypotonus maculopathy. Our study highlights the utility of mitomycin C as an adjunct in glaucoma filtering surgery and indicated that cyclosporin A may also be used as an antimetabolite.

Adolescent↗