General model of nonradiative excitation energy migration on a spherical nanoparticle with attached chromophores.

Theory of multistep excitation energy migration within the set of chemically identical chromophores distributed on the surface of a spherical nanoparticle is presented. The Green function solution to the master equation is expanded as a diagrammatic series. Topological reduction of the series leads to the expression for emission anisotropy decay. The solution obtained behaves very well over the whole time range and it remains accurate even for a high number of the attached chromophores. Emission anisotropy decay depends strongly not only on the number of fluorophores linked to the spherical nanoparticle but also on the ratio of critical radius to spherical nanoparticle radius, which may be crucial for optimal design of antenna-like fluorescent nanostructures. The results for mean squared excitation displacement are provided as well. Excellent quantitative agreement between the theoretical model and Monte-Carlo simulation results was found. The current model shows clear advantage over previously elaborated approach based on the Padé approximant.

Transition moment directions and selected spectroscopic properties of Ivabradine.

Based on the Kawski-Gryczynski method the value of angle ß=38° between absorption and fluorescence transition moments of Ivabradine was determined. Such a high value of ß is responsible for low emission anisotropy of Ivabradine in a rigid polyvinyl alcohol matrix and in anhydrous glycerol despite the elongated shape of the fluorophore. Selected steady-state and time-resolved spectroscopic results support the analysis.

Förster resonance energy transfer and trapping in selected systems: analysis by Monte-Carlo simulation.

Monte-Carlo simulation method is described and applied as an efficient tool to analyze experimental data in the presence of energy transfer in selected systems, where the use of analytical approaches is limited or even impossible. Several numerical and physical problems accompanying Monte-Carlo simulation are addressed. It is shown that the Monte-Carlo simulation enables to obtain orientation factor in partly ordered systems and other important energy transfer parameters unavailable directly from experiments. It is shown how Monte-Carlo simulation can predict some important features of energy transport like its directional character in ordered media.

Comments on the determination of excited state dipole moment of molecules using the method of solvatochromism.

The present note comments on several publications which appeared in different journals containing many inaccurate statements and lacking honest citations of basic papers dealing with the application of solvatochromism to determine excited state dipole moments.

Necrotic rhabdoid meningiomas with aggressive clinical behavior.

Rhabdoid meningioma (RM) is a rare, aggressive variant of meningioma classified as a WHO Grade III malignancy. RM exhibits a striking histological resemblance to other rhabdoid tumors and strong tendency towards local recurrences, CSF dissemination, and/or remote metastasis. The majority of reported cases are of secondary rhabdoid transformation in recurrent meningiomas. We present two unusual cases of rhabdoid meningiomas diagnosed as a primary intracranial lesion in adults that were associated with extensive necrosis and an aggressive clinical course. On histological examination, the majority of the tumor mass was composed of necrotic tissue with focal clusters of neoplastic cells, often localized around blood vessels. Most tumor cells exhibited typical rhabdoid morphology with large, vesicular, often eccentrically located nuclei with distinct nucleoli and abundant cytoplasm containing eosinophilic hyaline inclusions. Classical meningothelial features with focal whorl formation were scarce and seen only in one case; in the second case the tumor was entirely rhabdoid. The differential diagnosis with atypical teratoid/rhabdoid tumors (AT/RTs) and other neoplasms, particularly metastatic carcinoma, was considered. Immunohistochemical and electron microscopic study were critical for the accurate diagnosis of the rhabdoid subtype of meningiomas. Rhabdoid cells stained diffusely positive for vimentin and S-100 protein and showed focal but strong expression of epithelial membrane antigen and cytokeratins. The rhabdoid areas of the tumors exhibited high mitotic activity with a MIB-1 labeling index of 80 - 90%. The diagnosis of rhabdoid meningioma was supported by evidence of SNF5 (INI1) protein expression. Ultrastructural examination demonstrated the presence of interdigitating cell processes joined by numerous desmosomes and paranuclear whorls of intermediate filaments typical of the rhabdoid phenotype. Our two cases of rhabdoid meningiomas were associated with lethal outcome within a few months of initial diagnosis. Extensive necrosis in rhabdoid meningioma might be considered an additional predictor of aggressive clinical behavior.

Heavily lipidized, calcified giant cell glioblastoma in an 8-year-old patient, associated with neurofibromatosis type 1 (NF1): report of a case with long-term survival.

Giant cell glioblastoma (GCG-BM) with predominance of bizarre, multinucleated giant cells is a rare subtype of glioblastoma, however, its clinical behavior and histological features are still not fully understood. We report an unusual case of a heavily lipidized form of giant cell glioma corresponding mostly to GCGBM in a young patient with neurofibromatosis 1 (NF1). Histologically, the tumor revealed numerous characteristic histopathological features of giant cell glioblastoma including cellular pleomorphism with numerous giant tumor cells, pseudopalisades around necrotic foci and mitotic activity, accompanied by additional unique morphological elements such as massive lipidization of the neoplastic cells, abundant microcalcifications and angiomatous pattern of vascularization. Such aberrant morphology might be associated with the unusually long survival period of 12 years without clinical evidence of tumor recurrence. The coexistence of intracerebral heavily lipidized, calcified giant cell glioblastoma with NF1 has not been previously reported in literature.

Excitation energy transport and trapping in concentrated solid solutions of flavomononucleotide.

Excitation energy transport and trapping is studied for monomer-fluorescent dimer system of flavomononucleotide (FMN) in polyvinyl alcohol films (PVA). It is shown that the theory neglecting reverse energy transfer (RET) from dimers to monomers does not allow for the explanation of concentration quenching and concentration depolarization results presented herein. Much better agreement has been obtained using generalized energy transport theory in which fluorescent dimers are treated as imperfect traps for excitation energy. Such parameters like the dimer quantum yield and its emission anisotropy are estimated.

Pedunculated subependymomas of lateral ventricle.

The authors describe two cases of extremely rare, pedunculated subependymomas of lateral ventricle. One patient presented with symptoms of intracranial hypertension (case 2); CT scan revealed evidence of intraventricular mass, but in second patient (case 1) coexisting symptomatic anaplastic astrocytoma masked on CT-scan the presence of asymptomatic intraventricular tumour, which was found no earlier than at autopsy. The cellular origin of this rare intracranial neoplasm is discussed.

Tamoxifen perturbs lipid bilayer order and permeability: comparison of DSC, fluorescence anisotropy, laurdan generalized polarization and carboxyfluorescein leakage studies.

The perturbation of the lipid bilayer structure by tamoxifen may contribute to its multiple mechanisms of anticancer action not related to estrogen receptors. This study evaluates the effect of tamoxifen on structural characteristics of model membranes using differential scanning calorimetry (DSC), fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-[trimethylammonium)phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), as well as 6-dodecanoyl-2-dimethylaminonaphthalene (Laurdan) generalized polarization. The comparative measurements in multilammelar vesicles (MLV) prepared from dipalmitoylphosphatidylcholine (DPPC) revealed that tamoxifen decreases the phase transition temperature (Tm) paralleled by a broadening of the phase transition profile. In large unilamellar vesicles (LUV) prepared from egg yolk phosphatidylcholine (EPC), tamoxifen increased the lipid bilayer order predominantly in the outer bilayer region. From membrane permeability measurements, we conclude that the tamoxifen-induced release of entrapped carboxyfluorescein (CF) results from a permanent bilayer disruption and the formation of transient holes in the lipid bilayer.

[Light microscopic and ultrastructural features of nerve fibres in glomus tumor in two patients with long-term pain]. / Mikroskopowy i ultrastrukturalny obraz wlókien nerwowych w klebczaku u 2 pacjentów z wieloletnimi bólami.

Morphologic features of nerve fibres in two cases of glomus tumour, localized in thigh skin of 57- and 72-year-old men are reported. In the patients, the paroxysms of severe pain occurred 10 and over 11 years respectively. Histological, immunohistochemical and ultrastructural examination revealed tumour cells with features resembling that of epithelioid smooth muscle cells of normal glomus body. In addition, NF-immunopositive nerve fibres were identified in connective stroma of the tumour. Ultrastructural examination revealed bundles of thin, nonmyelinated axons, surrounded by Schwann cell cytoplasm. The majority of axons were under 0.5 micron in diameter and contained densely packed neurofilaments, whereas only few axons of larger diameter exhibited electron-lucent axoplasm with granular and clear vesicles. The bundles of nonmyelinated nerves were observed always within spaces filled by collagen fibrils and did not show any special relationship to glomus cells.

Primary intraspinal cervical melanoma.

A case of primary intraspinal melanoma is presented. This is a very rarely observed lesion, as only 37 cases have been described up to now. Patient presenting with signs and symptoms of spinal cord compression after MRI and spinal angiography was operated upon. Total removal of an intraspinal cervical tumour was performed. Histopathological investigation confirmed melanoma. Subsequent radiotherapy was given. Follow up of 4 years duration showed no signs of recurrence in MRI and full motor and sensory recovery.

[Intracranial complication of sinusitis in a 18-year old patient]. / Zatokopochodne powiklanie wewnatrzczaszkowe u 18-letniej chorej.

We have described a case of intracranial complications, which were caused by acute inflammation of maxillary sinus. In our patient we observed the development of multilocular intracranial abscesses located in left temporal lobe. However intracranial complications of sinusitis are rare, but they are still a serious problem that results in high mortality. The dominant features were: nighttime headache, fever, amnestic aphasia. The patient was treated surgically--utilizing traditional operation Caldwell-Luce'a. A conservative treatment was administrated during a long period including high-doses of i.v. antibiotics. This kind of patients require an interdisciplinary approach--radiological, neurosurgical and otolaryngological. The diagnosis was made with the aid of X-ray, CT-scan and cerebrospinal fluid examination. In spite of very intensive treatment the patient was unconscious one week. Her condition improved in the third week of her admission. CT-scanning carried out in first week showed brain infection. Repetition of Ct-scans of the head evidenced progression of disease by forming multiple abscesses in left temporal lobe excluding any neurosurgical treatment. Finally the patient's condition improved in the third week of her admission. She was discharged after six weeks of treatment without cranial nerve palsies. Amnestic aphasia lasted next six months.

Spectroscopic manifestations of flavomononucleotide dimers in polyvinyl alcohol films.

Absorption and fluorescence spectra of flavomononucleotide (FMN) in polyvinyl alcohol films (PVA) over a very wide concentration range are investigated. The dimerization constant as well as the pure monomer and dimer spectra are calculated and the structural parameters of FMN dimer are established. Excitation wavelength and temperature dependencies of FMN/PVA fluorescence spectra for different FMN concentrations were carried out. These measurements together with those of absorption reveal that dimers are imperfect traps for excitation energy and that the energy transfer can occur both in forward and in reverse direction. Moreover, it was shown that the observed temperature changes in fluorescence spectra may be qualitatively explained by the effect of inhomogeneous broadening of FMN energy levels and by the presence of fluorescent dimers.

Protein-dependent reduction of the pyrene excimer formation in membranes.

The presence of proteins in lipid bilayers always decreases the excimer formation rate of pyrene and pyrene lipid analogues in a way that is related to the protein-to-lipid ratio. Energy transfer measurements from intrinsic tryptophans to pyrene have shown (Engelke et al., 1994), that in microsomal membranes, the excimer formation rate of pyrene and pyrene fatty acids is heterogeneous within the membrane plane, because a lipid layer of reduced fluidity surrounds the microsomal proteins. This study investigates whether of not liposomes prepared from egg yolk phosphatidylcholine with incorporated gramicidin A give results comparable to those from microsomal membranes. The results indicate that the influence of proteins on the lipid bilayer cannot be described by one unique mechanism: Small proteins such as gramicidin A obviously reduce the excimer formation rate by occupying neighboring positions of the fluorescent probe and thus decrease the pyrene collision frequency homogeneously in the whole membrane plane, while larger proteins are surrounded by a lipid boundary layer of lower fluidity than the bulk lipid. The analysis of the time-resolved tryptophan fluorescence of gramicidin A incorporated liposomes reveals, that the tryptophan quenching by pyrene is stronger for tryptophans located closely below the phospholipid headgroup region because of the pyrene enrichment in this area of the lipid bilayer.

[Surgical treatment of brain tumors and intracarnial aneurysms in patients over 70 years]. / Operacje guzów mózgu i tetniaków u chorych powyzej 70 roku zycia.

Problem of surgical treatment in the elderly is still discussed in the literature. This group of patients needs especially clear criteria of qualification for extensive intracranial procedures. The authors present their own experience with 35 patients over 70 years old with intracranial tumours and intracranial aneurysms treated in Department of Neurosurgery, Warsaw Medical School between 1992-1993. Among 11 patients treated conservatively, only 3 patients were in poor physical state with functional limitation which was a contraindication for surgery. Postoperative mortality was 4.2%. On the basis of our experience we think that patients over 70 years can be safely operated on intracranial lesions and the age is not a contraindication for neurosurgical procedures.

Nonradiative excitation energy transport in one-component disordered systems.

High-accuracy Monte Carlo simulations of the time-dependent excitation probabilityG (s) (t) and steady-state emission anisotropyr M /r 0M for one-component three-dimensional systems were performed. It was found that the values ofr M /r 0M obtained for the averaged orientation factor[Formula: see text] only slightly overrate those obtained for the real values of the orientation factor κ ik (2) . This result is essentially different from that previously reported. Simulation results were compared with the probability coursesG (s) (t) andR(t) obtained within the frameworks of diagrammatic and two-particle Huber models, respectively. The results turned out to be in good agreement withR(t) but deviated visibly fromG (s) (t) at long times and/or high concentrations. Emission anisotropy measurements on glycerolic solutions of Na-fluorescein and rhodamine 6G were carried out at different excitation wavelengths. Very good agreement between the experimental data and the theory was found, with λex≈λ0-0 for concentrations not exceeding 3.5·10(-2) and 7.5·10(-3) M in the case of Na-fluorescein and rhodamine 6G, respectively. Up to these concentrations, the solutions investigated can be treated as one-component systems. The discrepancies observed at higher concentrations are caused by the presence of dimers. It was found that forλ ex <λ0-0 (Stokes excitation) the experimental emission anisotropies are lower than predicted by the theory. However, upon anti-Stokes excitation (λex>λ0-0), they lie higher than the respective theoretical values. Such a dispersive character of the energy migration can be explained qualitatively by the presence of fluorescent centers with 0-0 transitions differing from the "mean" at λ0-0.

Modulation of lymphocyte-fibroblast interactions by 2-chloro-2'-deoxyadenosine (2-CdA) in subarachnoid hemorrhage.

The adherence to monolayers of human fibroblasts of chromium-51 labelled peripheral blood mononuclear cells (PBMC) from normal subjects, and from patients after single or multiple subarachnoid hemorrhage (SAH), and the effect of 2-CdA on cell adhesion have been quantified. The fraction of cells adhering to fibroblasts were the lowest for multiple SAH patients and the highest for normal subjects, which can be explained by depletion of activated lymphocytes from peripheral blood of SAH patients. 2-CdA decreased the fraction of adhering cells isolated from normal subjects, did not change the adherence of cells from single SAH patients and increased the fraction of adhering cells isolated from multiple SAH patients. We conclude that the influence of 2-CdA on the adherence of PBMC to fibroblasts is inversely related to the degree of immune system activation.

Intracranial meningiomas following irradiation therapy for brain tumors.

Two cases of radiation-induced meningiomas following therapeutic irradiation given for primary diagnosed malignant brain tumor are presented. The meningiomas, histologically different from the initial brain tumor, appeared 15 and 21 years after high-dose brain irradiation. The possible risk of carcinogenesis within the CNS resulted from therapeutic cranial irradiation is stressed.

[Delayed results of using a new collagen-polyester dural prosthesis]. / Odlegle spostrzezenia uzycia kolagenowo-poliestrowego substytutu opony twardej.

A new dural prosthesis was prepared by bilateral coating of polyester net with radiation-modified collagen. Prosthesis is smooth highly flexible, water resistant and 0.3 mm thick. In the Department of Neurosurgery, Warsaw Medical Academy, Poland, 11 patients had a new dural prosthesis implanted, 1 with posttraumatic CSF-leakage and 10 with intracranial neoplasms. Early observation (2 to 4 weeks) and delayed (7 to 23 months) were performed. Neither allergic nor inflammatory reactions were observed. No CSF-leakage was observed. A new Polish dural substitute seems to be better than other ones because of its similarity to natural dura mater and low price.

A strategy for analyzing multiple parameters with application to aneurysmal SAH patients all of them clipped but treated with and without cyclosporine.

The study evaluated the effectiveness of the combination of nimodipine and cyclosporine A vs nimodipine alone in the prevention of delayed neurologic deficit in 82 (31 plus 51) patients in whom intracranial aneurysms were clipped within 72 h after subarachnoid haemorrhage. The tests performed included examination of the neurological condition before and after operation, angiography of cerebral arteries to visualize vasospasm, and analysis of the distribution and amount of blood in the brain fluids and/or tissue according to Fisher's scale. Inclusion of cyclosporine A in the treatment was clearly beneficial for the neurological condition. While cyclosporine A did not appear to produce a statistically significant improvement as evaluated by the chi-square test, a positive result was obtained following analysis of the correlation coefficients after Pearson in combination with the logistic log-linear regression analysis. The results argue against the utility of the chi-square test for verifying clinical data obtained in a limited number of patients.