A Dynamic Water Channel Affects O2 Stability in [FeFe]-Hydrogenases

[FeFe]-hydrogenases are capable of reducing protons at a high rate. However, molecular oxygen (O2 ) induces the degradation of their catalytic cofactor, the H-cluster, which consists of a cubane [4Fe4S] subcluster (4FeH ) and a unique diiron moiety (2FeH ). Previous attempts to prevent O2 -induced damage have focused on enhancing the protein's sieving effect for O2 by blocking the hydrophobic gas channels that connect the protein surface and the 2FeH . In this study, we aimed to block an O2 diffusion pathway and shield 4FeH instead. Molecular dynamics (MD) simulations identified a novel water channel (WH ) surrounding the H-cluster. As this hydrophilic path may be accessible for O2 molecules we applied site-directed mutagenesis targeting amino acids along WH in proximity to 4FeH to block O2 diffusion. Protein film electrochemistry experiments demonstrate increased O2 stabilities for variants G302S and S357T, and MD simulations based on high-resolution crystal structures confirmed an enhanced local sieving effect for O2 in the environment of the 4FeH in both cases. The results strongly suggest that, in wild type proteins, O2 diffuses from the 4FeH to the 2FeH . These results reveal new strategies for improving the O2 stability of [FeFe]-hydrogenases by focusing on the O2 diffusion network near the active site.

[Infraorbital lesion after scuba diving with chronic sinusitis: diagnosis and treatment of reverse block]

A 32-year-old diver repeatedly reported pain in the right side of the face after diving. He felt strong pain on pressure over the right face combined with hypaesthesia of the infraorbital nerve. In addition, he reported nasal breathing obstruction and problems regulating pressure in the middle ear. ENT consultation revealed a septal deviation to the right side of the nasal cavity. CT diagnosis showed the typical picture of chronic pansinusitis with total transfer of the right frontal sinus, subtotal transfer of the right ethmoid and subtotal transfer of the right maxillary sinus. Following successful functional sinus surgery (FESS), combined with septal surgery, the patient was able to dive again symptom-free.

[Brachytherapy in combination with function-preserving surgery of cancer of the paranasal sinus]

BACKGROUND

Prognosis of patients with advanced/recurrent cancer of paranasal sinuses and orbit with infiltration of the skull base is very bad. Radical surgery does not improve prognosis. A disadvantage of the radical surgery is the functional loss and the residual cosmetic defect. We present the results of a function-preserving surgery in combination with interstitial, image adapted brachytherapy (IABT) for the treatment of these cancers.

METHODS AND PATIENTS

Ten patients with paranasal sinus cancer and 16 patients with sarcomas (n=26) were retrospectively analysed. After a maximum tumor resection (mostly R1-R2 resections), 2-12 flexible afterloading plastic tubes were implanted. The postoperative IABT total dose was 10-25 Gy in 2.5 Gy fractions twice daily fractions for 5 days.

RESULTS

In all cases the eye was obtained without functional damage. The IABT was well tolerated. The visual and cosmetic results were satisfactory. Postoperative complications occurred in 7 out of 26 cases without a serious long-term adverse event. Significant radiation-induced complications were found in patients with orbital or skull base involvement. The three years overall survival was 60% for rhabdomyosarcoma, and 33% for the paranasal sinus cancers.

CONCLUSIONS

These results show that a combined treatment of function-preserving surgery and a IABT is a feasible, successful and well-tolerated option for curative, salvage and palliative therapy for selected patients with advanced or recurrent carcinoma of the paranasal sinuses and orbit.

[Jugular vein thrombosis caused by a neuroendocrine non-small cell lung cancer]

A 65-year-old patient presented with extensive swelling of the lateral neck. B-mode ultrasound showed an oval, well defined, hypoechoic formation consisting of multiple circular layers extending from the base of the skull to the subclavian vein. On subsequent computed tomography the size of the lesion was confirmed and the cause, a mediastinal mass compressing the superior caval vein, was identified. Histological examination of the mass revealed a neuroendocrine active non-small-cell-cancer of the lung. Treatment with high-dose heparin and antibiotics was started immediately, combined with palliative chemotherapy.The differential diagnosis of neck masses includes congenital, infectious, neoplastic and secondary causes due to disease in other regions of the body. Etiologies for jugular vein thrombosis include prolonged central venous catheterization, trauma, obstruction, infection as well as hypercoagulation. In order to diagnose masses in the head and neck region, other parts of the body need to be successively included if no local cause can be identified.

[A rare cause of facial asymmetry: nasoalveolar cyst: a clinical report]

Nasoalveolar cysts are rare nonodontogenic cysts that develop from the soft tissue in the mucobuccal area of the nasal ala. Their origin is a residuum of the nasolacrimal canal.

CLINICAL CASE

A 45-year-old woman had been aware of a painless tumor at the base of the nose and in the region of the left nasal ala for several months. We diagnosed a nasolabial cyst, which was extirpated in toto through a combined transvestibular-transnasal approach.

[A dural fistula as a rare cause for a pulse-synchronized tinnitus aurium]

Pulse-synchronized tinnitus aurium is commonly caused by vascular processes within the area of the temporal bone. With a microphone or a stethoscope in the external ear or on the mastoid perceptible noises can be heard by the physician. The most important differential diagnoses of an objective tinnitus are paraganglioma of the glomus jugulare or the glomus tympanicum, vascular stenosis, arteriovenouse malformations, aneurysms and atypic findings of the bulbus venae jugularis interna of the temporal bone. In case of a pulse-synchronized tinnitus purposeful use of neuroradiological diagnostic can lead to a correct diagnosis. The indication for invasive intervention of dural fistulas depends on the number and the hemodynamic relevance of these fistulas and on individual suffering of the patient. Even if it does not succeed, all to embolize AV-short-circuits, it is possible to reduce the intensity of the tinnitus in order to continue with conservative therapy.

[Brachytherapy in combination with function-preserving surgery. An interdisciplinary challenge]

A multimodal, interdisciplinary approach known as intensity-modified brachytherapy is a promising alternative for patients with advanced head and neck cancer infiltrating the orbita and skull base. An 87-year-old man presented with a recurrence of squamous cell carcinoma of the medial corner of the left eye that had been locally resected and irradiated by external beam radiotherapy multiple times. The cancer was resected with preservation of the eye with close margins, implantation of afterloading catheters, and reconstruction of the defect with a median forehead flap. The patient was irradiated with a total radiation dose of 30 Gy IMBT. After 1 year, there was no evidence of locoregional recurrence. The background of this therapeutic process and analysis of the current literature regarding this interdisciplinary treatment of head and neck cancer infiltrating the orbita and skull base are discussed based on this case report.

[Ki-67 antisense therapy in murine renal cell carcinoma models]

PURPOSE

The Ki-67 antigen is only expressed in proliferating cells. Previously, it was shown that Ki-67 derived antisense oligonucleotides (asONs) specifically inhibit the proliferation of tumor cells and tumour growth in vitro and in subcutaneous bladder and prostate tumor models. We intended to evaluate the effects of this therapeutic concept in two renal cell carcinoma (RCC) models.

MATERIAL AND METHODS

Human RCC cells (SK-RC 35) were initially transfected with FITC-labeled ONs and diffferent cationic lipids to analyze the transfection efficacy by flow cytometry (FACS). The potency of 14 different ONs sequences was compared by quantitative RT-PCR in vitro. For in vivo testing, ONs were administered to immunocompetent Balb/c mice bearing orthotopic RENCA tumors as well as to SCID mice bearing subcutaneous RCC SK-RC 35 xenografts. Tumor sizes and final tumor weights were documented. Additionally, several immunohistochemical staining procedures were performed.

RESULTS

FACS analysis showed highly effective transfection conditions in vitro. Systemic administration of asONs significantly decreased the tumour growth in the RENCA model (p < 0.05) and in the SCID mouse model (p = 0.009). Immunohistochemical staining of tumor specimens revealed a marked down-regulation of target protein and a slight increase in apoptotic cells after antisense treatment while the microvessel count was not significantly altered.

CONCLUSION

These results demonstrate that the Ki-67 antigen represents a suitable antiproliferative target and that asONs directed against this target are potent drugs that induce a significant inhibition of renal tumor growth in different mouse models.

Ki-67-directed antisense therapy in an orthotopic renal cell carcinoma model

PURPOSE

The Ki-67 antigen is only present in proliferating cells. We have shown previously that phosphorothioate-modified antisense oligonucleotides (ON) against this antigen are potent antitumoral agents in bladder and prostate cancer-derived cells. Since ON are known to accumulate in vivo in the kidney, high local effectivity may be expected. Here, we evaluated and characterized antitumoral effects in an orthotopic renal cell cancer (RENCA) model.

MATERIAL AND METHODS

RENCA cells were incubated with antisense and control ON in the presence of a cationic lipid. Uptake studies were performed with FITC-labeled ON. Ki-67 protein analysis after ON treatment was performed by immunohistochemical staining. For animal studies, 1 x 10(5) RENCA cells were implanted under the renal capsule of Balb/c mice. Antisense and control ON were injected intraperitoneally daily for 14 days. Tumor weights and status of metastasis were documented after sacrifice. Furthermore, vessel density in tumor tissues was determined by CD31 immunolabeling.

RESULTS

Antisense treatment of RENCA cells resulted in specific reduction of the Ki-67 protein and inhibition of cell growth. A substantial cellular uptake of labeled ON was noted in vitro and in vivo. The growth of orthotopically implantated syngeneic kidney tumors in immunocompetent mice was significantly inhibited in antisense-treated animals (p < 0.05). Furthermore, lung metastases were noted in 10% of antisense-treated animals compared to 30-40% in control groups. Immunohistochemical staining of the vessel density showed no significant difference among treatment groups.

CONCLUSIONS

The results demonstrate that Ki-67-directed antisense oligonucleotides are potent inhibitors of target protein expression and proliferation of tumor cells in vitro, and of tumor growth and lung metastasis formation in murine renal cell carcinoma whereas tumor vascularization is not significantly affected.