Molecular genetic studies of early breast cancer evolution

Summary In the past few years there has been an explosion in the number of patients diagnosed with hyperplastic breast disease andin situ breast cancer. Based on epidemiological data, these morphologically defined lesions may be categorized as those with little malignant potential (e.g. typical hyperplasia or proliferative disease without atypia [PDWA]), those with significant malignant potential which may already be initiated (e.g. atypical ductal hyperplasia [ADH]), and early transformed lesions which are malignant but not yet invasive (e.g. ductal carcinomain situ [DCIS]). They may represent sequential evolutionary stages in the ontogeny of invasive breast cancer, with each morphologically defined stage resulting from accumulating genetic changes culminating in a transformed clonal lineage capable of invasion and metastasis. Using loss-of-heterozygosity (LOH) analysis, we are studying the genetic changes associated with these lesions in archival tissue samples. 50% (6/12) of the proliferative lesions (PDWA and ADH) and 80% of the DCIS shared their LOH patterns with more advanced lesions from the same breast, strongly supporting a precursor/product relationship between these lesions and the cancers they accompany.     

A genetic study of idiopathic focal dystonias

The inheritance of focal dystonias was investigated in 43 families containing 43 index cases with torticollis (n = 21), blepharospasm (n = 18) and writer's cramp (n = 4). They generated a potential population of 235 first-degree relatives, and 168 out of 179 living first-degree relatives were examined. Ten relatives with dystonia were identified in ten families. Another two parents from two of the same group of ten families were affected according to the family history. The majority of the secondary cases (six patients, five siblings, and one child) were not aware of any dystonia. The tendency for affected relatives to have the same type of dystonia as index patients was observed only for torticollis. Overall, 23% of index patients had relatives with dystonia. Segregation analysis suggested the presence of an autosomal dominant gene or genes with reduced penetrante underlying focal dystonia.     

Photorefractive keratectomy with the erbium: YAG laser

BACKGROUND: Ablation experiments and preclinical studies have shown increased thermal damage and surface roughness after photorefractive keratectomy (PRK) with the erbium: YAG laser. MATERIALS AND METHODS: In this study, the thermal damage was investigated on enucleated pig corneas for various laser pulse durations (80 ns to 1 ms) and radiant exposures (0.2-5 J/cm2). The "scanning-spot" method and the fundamental mode photo-ablation were used for spherical corrections. SEM pictures and surface roughness measurements enabled comparison with the morphology after ArF-excimer laser treatment. The surface roughness is one order of magnitude higher compared to the ArF-excimer laser ablation. The surface of the tissue after ablation looks melted. RESULTS: The thermal damage reduces with increased intensity, and at high intensities the thermal damage results in a constant thickness of > 5 microns. CONCLUSIONS: Laser-induced melting processes might be the main reason for the high thermal damage and the increased surface roughness after erbium: YAG laser treatment. This leads to the conclusion that the erbium: YAG laser is not a real alternative to the ArF-excimer laser in PRK.     

Ultrastructural organization of proteoglycans and fibrillar matrix of the tectorial membrane

The molecular and supramolecular structure of the tectorial membrane (TM) was studied by transmission electron microscopy (TEM). Collagen (type A) fibrils in the TM were found associated with proteoglycans (PGs) and type B fibrils. Most PGs were orthogonally oriented and attached D-periodically to collagen fibrils. Computer averaged projections of PG particles and linear aggregates of PGs in crystalline arrays, stained with Cuprolinic blue, showed an elongated, electron-dense structure 50–65 nm in length and 10 nm in width. Image analysis of type B fibrils showed that they are constructed of globular domains arranged with a periodicity of 12–14 nm. Each globular domain contains two thin ‘arms', extended in opposite directions, which contact the ‘arms' of adjacent fibrils. Numerous type B fibrils were found between collagen fibrils. They are attached to adjacent collagen fibrils by the ‘arms' of their globular domains. An association of type B fibrils and PGs with collagen seems to result in the local ordered arrangement of the TM matrix. A hypothetical model of the TM matrix supramolecular structure is presented.     

Time-dependent inhibition and tetrahydrobiopterin depletion of endothelial nitric-oxide synthase caused by cigarettes.

Smoking causes a dysfunction in endothelial nitric-oxide synthase (eNOS), which is ameliorated, in part, by administration of tetrahydrobiopterin (BH(4)). The exact mechanism by which the nitric oxide deficit occurs is unknown. We have previously shown that aqueous extracts of chemicals in cigarettes (CE) cause the suicide inactivation of neuronal NO synthase (nNOS) by interacting at the substrate-binding site. In the current study, we have found that CE directly inactivates eNOS by a process that is not affected by the natural substrate l-arginine and is distinct from the mechanism of inactivation of nNOS. We discovered that CE causes a time-, concentration-, and NADPH-dependent inactivation of eNOS in an in vitro system containing the purified enzyme, indicating a metabolic component to the inactivation. The CE-treated eNOS but not nNOS was nearly fully reactivated upon incubation with excess BH(4), suggesting that BH(4) depletion is a potential mechanism of inactivation. Moreover, in the presence of CE, eNOS catalyzed the oxidation of BH(4) to dihydrobiopterin and biopterin by a process attenuated by high concentrations of superoxide dismutase but not catalase. We speculate that a redox active component in CE, perhaps a quinone compound, causes oxidative uncoupling of eNOS to form superoxide, which in turn oxidizes BH(4). The discovery of a direct inactivation of eNOS by a compound(s) present in tobacco provides a basis not only for further study of the mechanisms responsible for the biological effects of tobacco but also a search for a potentially novel inactivator of eNOS.     

Simulation of Diffusion-Controlled Growth of Interdependent Nuclei under Potentiostatic Conditions

The problem of diffusion-controlled growth following an instantaneous nucleation event was studied within the framework of a new numerical model, considering the spatial distribution of hemispherical nuclei on the electrode surface and the mutual influence of growing nuclei via the collision of 3D diffusion fields. The simulation of the diffusion-controlled growth of hexagonal and random ensembles was performed at the overpotential-dependent number density of nuclei. The diffusion flow to each nucleus within a random ensemble was simulated by the finite difference method using the derived analytical expressions for the surface areas and the volumes formed at the intersection of 3D diffusion fields with the side faces of a virtual right prism with a Voronoi polygon base. The implementation of this approach provides an accurate calculation of concentration profiles, time dependences of the size of nuclei, and current transients. The results, including total current density transients, growth exponents, and nucleus size distribution, were compared with models developed within the concept of planar diffusion zones, the mean-field approximation and the Brownian dynamics simulation method, as well as with experimental data from the literature. The prospects of the model for studying the initial stages of electrocrystallization were discussed.     

A Feasibility Study of High-Entropy Alloy Coating Deposition by Detonation Spraying Combined with Laser Melting

In this work, a new two-stage approach to the deposition of high-entropy alloy coatings is proposed. At the first stage, a composite precursor coating is formed by detonation spraying of the metal powder mixtures. At the second stage, the precursor coating is re-melted by a laser, and the formation of multi-component solid solution phases can be expected upon solidification. The feasibility of the proposed approach was validated using three different mixtures of Fe, Ni, Cu, Co and Al powders. It was shown that detonation spraying allows forming composite coatings with a uniform distribution of the lamellae of different metals. The results of the structural analysis of the laser-treated coatings suggest that complete alloying occurred in the melt and face-centered cubic solid solutions formed in the coatings upon cooling.     

One intrauterine device lost, two found

During a search for a recently inserted, lost intrauterine device (IUD), a pelvic x-ray found two devices. One of the IUDs had been inserted 9 years earlier and was thought expelled.     

Combination of endobronchial bronchoscopic debulking and bronchoplastic segmentectomy of an obstructive neuroendocrine tumour: probably the least invasive approach

We report the case of a female patient with an obstructing well-differentiated neuroendocrine tumour in the apical segment of the completely atelectatic right lower lobe. Bronchoscopic debulking of the tumour lead to re-ventilation of the remaining lobe, allowing to perform a lung-sparing bronchoplastic resection of the affected segment by uniportal video-assisted thoracic surgery.