Canal wall reconstruction and mastoid obliteration with composite multi-fractured osteoperiosteal flap

We used inferior pedicled composite multi-fractured osteoperiosteal flap (CMOF), our original and new surgical approach, to obliterate the mastoid cavity and reconstruct the external auditory canal (EAC) to prevent the open cavity problems. CMOF was used to obliterate the mastoid cavity and reconstruct the EAC in 24 patients (13 women, 11 men; age span 12–51 years) who underwent radical mastoidectomy to treat the chronic otitis media between 1998 and 2004. Small meatoplasty was done in all 24 patients to relive their aesthetical concerns. Temporal bone CT scanning was done to observe the neo-osteogenesis in the mastoidectomy cavity and the CMOF, and the EAC volume was measured postoperatively. All our patients were followed-up for 2 years. The epithelization of the new EAC in our patients was complete at the end of the second month. Cholesteatoma, granulation, and recurrence of osteitis did not occur in any of the patients. We saw the new bone formation filling the mastoid cavity in the postoperative temporal bone CT scanning images. The mean volume of the new EAC on the 24th month was 1.83 ± 0.56 cm³. We had an almost natural EAC, which owed its existence to the neo-osteogenesis that grows behind the CMOF, which we use to obliterate the mastoid cavity and to reconstruct the EAC.This technique, composite multi-fractured osteoperiosteal flap, was presented in the symposium of Gulhane Military Medical Academy on otology and audiology, 15–18 September, 2005, Antalya, Turkey.     

The glycine receptor: pharmacological studies and mathematical modeling of the allosteric interaction between the glycine- and strychnine-binding sites

The displacement by glycine of 3H-strychnine binding to rat spinal cord membranes cannot be explained by a simple competitive interaction. Indeed, protein-modifying reagents can completely abolish the inhibition of 3H-strychnine binding by glycine and other agonists, whereas the interaction of strychnine itself and other related compounds with the binding site is unimpaired. Moreover, glycine cannot inhibit completely saturable 3H-strychnine binding, the extent of its maximum inhibitory effect depending on the ionic composition of the medium. Hill coefficients less than 1 (whose magnitude also depends on the assay medium) were obtained from glycine displacement curves. These properties are consistent with a mathematical model of two different, but mutually interacting, binding sites for strychnine and glycine on the glycine receptor. The effect of ions and protein-modifying reagents might be explained in this model as modifications of the mechanisms that mediate the allosteric interaction, and/or the affinity of glycine for the receptor. The agonists beta-alanine and taurine and the new antagonists, THAZ, iso-THAZ, and 4,5-TAZA, also seem to interact with a site different from the strychnine-binding site, probably the glycine-binding site.     

Cyclophosphamide affects the dynamics of granuloma formation in experimental visceral leishmaniasis

We observed histopathological and ultrastructural hepatic changes following the intracardiac inoculation ofLeishmania donovani amastigotes into inbred LHC hamsters (group I). Since granuloma formation is known to be T-cell-dependent, we also examined infected hamsters under cyclophosphamide immunosuppressive treatment (group ICy) and evaluated the production of interleukin-2 (IL-2) by their cells. Group I showed more intense hepatocyte and endothelial cell clasmatosis as well as hepatocyte degeneration and necrosis, deposits of connective tissue fibers, granulomas with multinucleated giant cells (MGCs) of foreign-body and Langhans' types and reduced production of IL-2 by spleen cells. In contrast, group ICy hamsters exhibited larger eosinophil and lymphocyte populations within sinusoids and peri-sinusoidal areas but showed no MGCs in granulomas. A striking decline in IL-2 production was noted. These results suggest that cyclophosphamide induces a delay in the natural evolution ofL. donovani-induced granulomatous hepatic inflammation.     

Testicular torsion: Evaluation of contralateral testicular histology

Infertility may occur in patients with unilateral testicular torsion whose contralateral testis is intact. Depending on this observation, the physicians have begun to examine the contralateral testis. In the present prospective study we aimed to examine the histopathologic alterations occurring in the contralateral testicle with time. Sixty adult male albino rats were included in the programme, and following experimental torsion the histopathologic findings, especially those in the contralateral testis, were evaluated after 4–12 weeks. Long-term and high degree torsion of the testicle led to varying degrees of deterioration in the germinal epithelium and interstitial cells of the contralateral testicle. Histopathologic alterations were reversed in 12 weeks. Tubular diameter and testicular volume also decreased in accordance with the histopathologic alteration. In our opinion, orchiectomy following torsion of one testicle will limit potential histopathologic alterations in the contralateral testicle.     

Synthesis of poly[isobutyl (2S,3R)-3-benzyloxyaspartate]

A chiral poly(3-substituted isobutyl D -aspartate) 12 was synthesized by polymerization of the chiral β-lactam 11 derived from D -glyceraldehyde. The new polyamide was characterized by elemental analyses, and infrared, ¹H- and ¹³C nuclear magnetic resonance spectroscopies. The molecular weight was estimated as 543 000 and 230 000 on the basis of viscosimetric measurements and gel-permeation chromatography, respectively. Polyamide 12 is soluble in a variety of organic solvents including chloroform.     

Differential Stimulation of Noradrenaline Release by Reversal of the Na+/Ca2+ Exchanger and Depolarization in Chromaffin Cells

We compared the effectiveness of Ca²⁺ entering by Na⁺/Ca²⁺ exchange with that of Ca²⁺ entering by channels produced by membrane depolarization with K⁺ in inducing catecholamine release from bovine adrenal chromaffin cells. The Ca²⁺ influx through the Na⁺/Ca²⁺ exchanger was promoted by reversing the normal inward gradient of Na⁺ by preincubating the cells with ouabain to increase the intracellular Na⁺ and then removing Na⁺ from the external medium. In this way we were able to increase the cytosolic free Ca²⁺ concentration ([Ca²⁺]_c) by Na⁺/Ca²⁺ exchange to 325 ± 14 nM, which was similar to the rise in [Ca²⁺]_c observed upon depolarization with 35 mM K⁺ of cells not treated with ouabain. After incubating the cells with ouabain, K⁺ depolarization raised the [Ca²⁺]_c to 398 ± 31 nM, and the recovery of [Ca²⁺]_c to resting levels was significantly slower. Reversal of the Na⁺ gradient caused an −6-fold increase in the release of noradrenaline or adrenaline, whereas K⁺ depolarization induced a 12-fold increase in noradrenaline release but only a 9-fold increase in adrenaline release. The ratio of noradrenaline to adrenaline release was 1.24 ± 0.23 upon reversal of the Na⁺/Ca²⁺ exchange, whereas it was 1.83 ± 0.19 for K⁺ depolarization. Reversal of the Na⁺/Ca²⁺ exchange appeared to be as efficient as membrane depolarization in inducing adrenaline release, in that the relation of [Ca²⁺]_c to adrenaline release was the same in both cases. In contrast, we found that for the same average [Ca²⁺]_c, the Ca²⁺ influx through voltage-gated channels was much more efficient than the Ca²⁺ entering through the Na⁺/Ca²⁺ exchanger in inducing noradrenaline release from chromaffin ceils. This greater effectiveness of membrane depolarization in stimulating noradrenaline release suggests that there is a pool of noradrenaline vesicles which is more accessible to Ca²⁺ entering through voltage-gated Ca²⁺ channels than to Ca²⁺ entering through the Na⁺/Ca²⁺ exchanger, whereas the adrenaline vesicles do not distinguish between the source of Ca²⁺.