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Biomedical subjects

A Kania

Publications and source records attributed to A Kania.

At least 19 recordsLinked to original sources
PubMed2005

IMRT for breast. a planning study.

BACKGROUND AND PURPOSE: To evaluate the performance of ten different treatment-planning systems when intensity modulated (IMRT) plans are designed for breast treatments that include the irradiation of the internal mammary chain. PATIENTS AND METHODS: A dataset of five patients (CT images and volumes of interest) was distributed to design IMRT plans on the ten systems. To minimise biases, the same geometry and clinical planning aims were imposed on the individual plans. Results were analysed in terms of dose distributions and dose volume histograms. RESULTS AND CONCLUSIONS: For target coverage, the volume receiving more than 95% of the prescribed dose ranged from 77% (OTP) to 91% (Eclipse and Pinnacle), the volume receiving more than 107% ranged from 3.3% (Hyperion) to 23.2% (OTP). The mean dose to ipsilateral lung ranged from 13 Gy (Eclipse) to 18 Gy (OTP). The volume of the contralateral breast receiving more than 10 Gy ranged from 3% (Pinnacle) to 26% (Precise). The volume of heart receiving more than 20 Gy ranged from 7% (Eclipse) to 47% (Precise), the maximum significant dose to heart ranged from approximately 27 Gy (XiO) to approximately 49 Gy (Precise). The maximum significant dose to healthy tissue ranged from approximately 51 Gy (Eclipse) to approximately 62 Gy (OTP). It was also possible to show that the treatment geometry proposed here enables to minimise contralateral breast irradiation while keeping minimal ipsilateral lung (or heart) involvement and satisfactory target coverage.

Breast Neoplasms↗
PubMed2001

Basic concepts of CORVUS dose model.

Basic concepts of the dose model utilized in the CORVUS treatment planning system are reviewed. Following the Peacock delivery tool (MIMiC) by NOMOS Corporation, CORVUS "delivers" radiation to a patient by means of narrow x-ray beams (pencil beams), which are subject to lateral electronic disequilibrium. Dose data for such beams are difficult to obtain experimentally. Therefore, the CORVUS dose model uses analytically calculated (rather than experimentally measured) narrow-beam dose data. The model is based on the idea that physical parameters necessary to calculate absorbed dose in narrow x-ray beams can be derived from measured broad-beam dose data. Calculation of central-axis and off-axis absorbed dose in narrow beams as well as a method of generating beam profiles are described.

Humans↗
PubMed2001

New analogues of bradykinin containing a conformationally restricted dipeptide fragment in their molecules.

The present paper describes the synthesis and some pharmacological properties of two new bradykinin analogues containing the ethylene-bridged dipeptide Phe-Phe in their molecules. In a further two peptides this modification was combined with acylation of the N-terminus with 1-adamantaneacetic acid. Finally, we synthesized four analogues by removing the Ser6 residue from the four peptides mentioned above. The activity of the new analogues was assayed on isolated rat uterus (RUT) and in rat blood pressure tests (BPT). The results clearly indicate that the proposed modification, alone or in combination with other changes, resulted in either a drop in antiuterotonic activity or even in conversion to an agonism. Although this tendency is not so distinct in blood pressure assays, the antagonistic potency of the new analogues is also diminished. Nevertheless, it was demonstrated that the D-amino acid in position 7 which, until recently, was considered necessary for antagonism, may be replaced, together with the amino acid occupying position 8, by a suitable, sterically restricted L,L-dipeptide unit.

Acetic Acid↗
PubMed2001

[Pulmonary lymphangioleiomyomatosis as a very rare interstitial lung disease].

Lymphangioleiomyomatosis (LAM) is a rare lung disease affecting premenopausal women characterized by an abnormal proliferation of smooth muscle cells that leads to the obstruction of airways, lymph and blood vessels. We present a case of a 46-year-old woman who was admitted to our department with dyspnoea and dry cough. The patient had a history of spontaneous pneumothorax 2 years prior to admission. Physical examination revealed dull percussion note on the lower right side of the chest. The chest X-ray film showed diffuse interstitial parenchymal infiltration and flattened costodiaphragmatic angle on the right side. The high resolution computerized tomography (HRCT) scan showed the numerous air filled cysts, about 25 mm in diameter with thin regular walls and liquid in the right pleural cavity. The effusion in a pleural cavity was chylous. Airway obstruction (FEV1/FVC 57% of predicted), markedly elevated residual volume (140%), and decreased DLCO were observed in functional pulmonary tests, and she underwent diagnostic videothoracoscopy. Pulmonary biopsy specimens confirmed diagnosis of LAM. The patient has been under careful observation, no treatment was instituted. The patient remains clinically stabile. During the last six months of observation she has normal sex hormone levels, therefore there exists a possibility of postmenopausal remission of symptoms.

Female↗
PubMed2000

Coordinate roles for LIM homeobox genes in directing the dorsoventral trajectory of motor axons in the vertebrate limb.

Motor neurons extend axons along specific trajectories, but the molecules that control their pathfinding remain poorly defined. We show that two LIM homeodomain transcription factors, Lim1 and Lmx1b, control the initial trajectory of motor axons in the developing mammalian limb. The expression of Lim1 by a lateral set of lateral motor column (LMC) neurons ensures that their axons select a dorsal trajectory in the limb. In a complementary manner, the expression of Lmx1b by dorsal limb mesenchymal cells controls the dorsal and ventral axonal trajectories of medial and lateral LMC neurons. In the absence of these two proteins, motor axons appear to select dorsal and ventral trajectories at random. Thus, LIM homeodomain proteins act within motor neurons and cells that guide motor axons to establish the fidelity of a binary choice in axonal trajectory.

Animals↗
PubMed2000

Lim1 activity is required for intermediate mesoderm differentiation in the mouse embryo.

During gastrulation and early organogenesis, Lim1 is expressed in the visceral endoderm, the anterior mesendoderm, and the lateral mesoderm that comprises the lateral plate and intermediate mesoderm. A previous study has reported that kidneys and gonads are missing in the Lim1 null mutants (W. Shawlot and R. R. Behringer, 1995, Nature 374, 425-430). Results of the present study show that in the early organogenesis stage mutant embryo, the intermediate mesoderm that contains the urogenital precursor tissues is disorganized and displays diminished expression of PAX2 and the Hoxb6-lacZ transgene. When posterior epiblast cells of the Lim1 null mutant embryo were transplanted to the primitive streak of wild-type host embryos, they were able to colonize the lateral plate and intermediate mesoderm of the host, suggesting that Lim1 activity is not essential for the allocation of epiblast cells to these mesodermal lineages. However, most of the mutant cells that colonized the lateral and intermediate mesoderm of the host embryo did not express the Hoxb6-lacZ transgene, except for some cells that were derived from the distal part of the posterior epiblast. Lim1 activity may therefore be required for the full expression of this transgene that normally marks the differentiation of the lateral plate and intermediate mesoderm.

Animals↗
PubMed2000

New bradykinin analogs in contraction of rat uterus.

In this study, we evaluated 20 of our previously synthesized peptides on isolated rat uterus by Holton's procedure with minor modifications, and compared their activity with that assessed previously by their ability to inhibit vasodepressor response to exogenous bradykinin (BK) in conscious rats. We used [D-Arg(0), Hyp(3), Thi(5, 8), (D-Phe)(7)]BK, the B(2) antagonist of Vavrek and Stewart as a model when designing our analogs. We observed that, in the case of the rat uterus test, the activity of peptides modified by acylation of the N-terminus with various bulky groups depends substantially on the chemical character of the substituent. We also learned that, contrary to previous examples, acylation of the N-terminus of antagonists, which contain a sterically restricted fragment in the C-terminal part, may not improve their antagonistic potencies. Besides an improved characterization of a series BK analogs, our studies have provided new information on the structure-activity relationship, which in turn may be of value in the design of more potent and selective bradykinin antagonists. The results of our studies appear to support the hypothesis of others about the presence of different subtypes of B(2) receptors in rat uterus and blood vessels.

Animals↗
PubMed2000

Silver niobium trioxide, AgNbO3

The present structure determination of silver niobium trioxide at 291 K was performed on a twinned single crystal with a predominant presence [about 93 (1)%] of one twin domain. The sample contained traces of V (about 1 atomic %). This study confirms that the room-temperature phase of AgNbO(3) is isostructural with the room-temperature phase of NaNbO(3), i.e. it is a tilted perovskite. Structural deviation in AgNbO(3) from centrosymmetry was not detected in this study and its structure was refined in Pbcm, though a previous study indicated ferroelectricity below 350 K, in contrast with NaNbO(3).

Journal Article↗
PubMed2000

[Seroprevalence of viral hepatitis A, B and C in intravenous drug users].

Markers of viral hepatitis A-C of 99 intravenous drug users predominantly (in 96%) from the Karviná district were examined from March 1998 to February 1999. Pervitin (methamphetamine) was the basic drug in all subjects. Anti-HAV was detected in 6.4% of VHA non-vaccinated individuals, anti-HAV/IgM was not found in any case, HBsAg was detected in 4.0% (acute VHB was diagnosed in all these cases), anti-HBc in 9.2% and anti-HCV in 25.0% of the investigated cases. Our results confirmed the importance of drug use by injection, esp. needle sharing, for the spread VHB and VHC. In case of VHA the fecal-oral route of transmission in this subpopulation is dominant.

Adolescent↗
PubMed1999

Theoretical considerations of monitor unit calculations for intensity modulated beam treatment planning.

A treatment planning system to compute intensity modulated radiotherapy (IMRT) treatments using inverse planning was investigated. The system was designed to optimize the intensity patterns required to treat a specified target volume with specified normal structure constraints. A beam model that uses the convolution of pencil beams was used to compute the dose distributions. A multileaf collimator leaf-setting sequence intended to produce the intensity pattern was computed along with the monitor units required to deliver each of a number of fixed-gantry modulated fields. Computer calculations are commonly verified using an independent manual procedure. It is difficult to calculate treatment delivery monitor units for this variant of IMRT using manual methods. Since manual calculations are not feasible, it is important both to understand and to verify the calculation of treatment monitor units by the planning system algorithm. A formal analysis was made of the dose calculation model and the monitor unit calculation embedded in the algorithm. Experimental verification of the dose delivered by plans computed with the methodology demonstrated an agreement of better than 4% between the dose model and measurements.

Algorithms↗
PubMed1999

Lim1 is required in both primitive streak-derived tissues and visceral endoderm for head formation in the mouse.

Lim1 is a homeobox gene expressed in the extraembryonic anterior visceral endoderm and in primitive streak-derived tissues of early mouse embryos. Mice homozygous for a targeted mutation of Lim1 lack head structures anterior to rhombomere 3 in the hindbrain. To determine in which tissues Lim1 is required for head formation and its mode of action, we have generated chimeric mouse embryos and performed tissue layer recombination explant assays. In chimeric embryos in which the visceral endoderm was composed of predominantly wild-type cells, we found that Lim1(-)(/)(-) cells were able to contribute to the anterior mesendoderm of embryonic day 7.5 chimeric embryos but that embryonic day 9.5 chimeric embryos displayed a range of head defects. In addition, early somite stage chimeras generated by injecting Lim1(-)(/)(-) embryonic stem cells into wild-type tetraploid blastocysts lacked forebrain and midbrain neural tissue. Furthermore, in explant recombination assays, anterior mesendoderm from Lim1(-)(/)(-) embryos was unable to maintain the expression of the anterior neural marker gene Otx2 in wild-type ectoderm. In complementary experiments, embryonic day 9.5 chimeric embryos in which the visceral endoderm was composed of predominantly Lim1(-)(/)(-) cells and the embryo proper of largely wild-type cells, also phenocopied the Lim1(-)(/)(-) headless phenotype. These results indicate that Lim1 is required in both primitive streak-derived tissues and visceral endoderm for head formation and that its inactivation in these tissues produces cell non-autonomous defects. We discuss a double assurance model in which Lim1 regulates sequential signaling events required for head formation in the mouse.

Animals↗
PubMed1995

Immunocytochemical analysis of axonal outgrowth in synaptotagmin mutations.

Synaptotagmin is a synaptic vesicle specific protein that binds calcium and phospholipids in vitro and is required for calcium-regulated fusion of synaptic vesicles with the presynaptic membrane. We have examined the possible requirement for synaptotagmin in axonal outgrowth by following neuronal development in Drosophila embryos deficient for the synaptotagmin gene. We find that synaptotagmin is expressed abundantly in axons and growth cones before synapse formation in wild-type embryos. Using antibodies to the intravesicular domain of synaptotagmin to label live embryos, we demonstrate that vesicle populations containing synaptotagmin actively undergo exocytosis during axonogenesis. We have used immunocytochemical techniques to examine the distribution of the axonal protein Fasciclin II, the presynaptic membrane protein syntaxin, and the synaptic vesicle protein cysteine string protein, in synaptotagmin null mutations. The distribution of these proteins is similar in wild-type and synaptotagmin mutant embryos, suggesting that synaptotagmin is not required for axonogenesis in the CNS or PNS. Based on these findings, we suggest that the molecular mechanisms underlying vesicular-mediated membrane expansion during axonal outgrowth are distinct from those required for synaptic vesicle fusion during neurotransmitter release.

Animals↗
PubMed1995

P-element mutations affecting embryonic peripheral nervous system development in Drosophila melanogaster.

The Drosophila embryonic peripheral nervous system (PNS) is an excellent model system to study the molecular mechanisms governing neural development. To identify genes controlling PNS development, we screened 2000 lethal P-element insertion strains. The PNS of mutant embryos was examined using the neural specific marker MAb 22C10, and 92 mutant strains were retained for further analysis. Genetic and cytological analysis of these strains shows that 42 mutations affect previously isolated genes that are known to be required for PNS development: longitudinals lacking (19), mastermind (15), numb (4), big brain (2), and spitz (2). The remaining 50 mutations were classified into 29 complementation groups and the P-element insertions were cytologically mapped. The mutants were classified in five major classes on the basis of their phenotype: gain of neurons, loss of neurons, organizational defects, pathfinding defects and morphological defects. Herein we report the preliminary phenotypic characterization of each of these complementation groups as well as the embryonic lacZ expression pattern of each P-element strain. Our analysis indicates that in most of the P-element insertion strains, the lacZ reporter gene is not expressed in the developing PNS.

Animals↗
PubMed1993

Neuromusculin, a Drosophila gene expressed in peripheral neuronal precursors and muscles, encodes a cell adhesion molecule.

To unravel the molecular mechanisms of peripheral nervous system differentiation in Drosophila, we have screened for and identified genes that are expressed in sensory mother cells. Here, we describe a novel gene, neuromusculin (nrm), that is expressed in sensory mother cells and developing muscles. nrm encodes a member of the immunoglobulin superfamily. Immunoblots of Schneider 2 cells transfected with an nrm cDNA indicate that Nrm is present in a membrane-associated form and a secreted form. Cell aggregation assays suggest that Nrm is a homophilic cell adhesion molecule that is secreted or released after proteolysis, a mechanism that to our knowledge has not been described for immunoglobulin-like molecules. Genetic analyses indicate that nrm is an essential gene required for larval viability. We propose that Nrm may play a role as a cell adhesion molecule in clustering cells of the peripheral nervous system, neuronal fasciculation, and/or pathfinding.

Amino Acid Sequence↗