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Biomedical subjects

J Schirmer

Publications and source records attributed to J Schirmer.

At least 19 recordsLinked to original sources
PubMed2006

Validating self reported home safety practices in a culturally diverse non-inner city population.

OBJECTIVE: To determine the validity of face to face, self reported responses to questions about the presence of safety devices and use of safety practices in the home aimed at preventing unintended injuries to preschool aged children. METHODS: The authors invited families with children enrolling in a medium sized Midwestern US community Head Start program to participate in a randomized study of home safety practices. Participation involved consenting parents (n = 452) completing an initial questionnaire during Head Start enrollment or in their home. Project staff conducted home inspections to confirm parental responses to 16 questions. Only inspections conducted within 34 days of questionnaire completion (n = 259) were included in the validation study. Parents were told that the home visit would assess the need for safety devices, but were not informed of the validation aspect of the study. RESULTS: Sensitivities were generally high for all 16 safety practices, whereas negative predictive value and specificity varied considerably. Positive predictive value was also high for most practices, and did not vary by ethnicity. Answers provided by parents in their home were different and more reliable than those provided by parents interviewed at school (p = 0.001). CONCLUSIONS: Use of safety devices and practices by parents of preschool aged children reported in a face to face interview are generally reliable. Reliability increases if the interview is conducted in the home. Parents may also be more willing to report potential problems if they perceive they may receive corrective assistance.

Accident Prevention↗
PubMed2005

Molecular ionization energies and ground- and ionic-state properties using a non-Dyson electron propagator approach.

An earlier proposed propagator method for the treatment of molecular ionization is tested in first applications. The method referred to as the non-Dyson third-order algebraic-diagrammatic construction [nD-ADC(3)] approximation for the electron propagator represents a computationally promising alternative to the existing Dyson ADC(3) method. The advantage of the nD-ADC(3) scheme is that the (N+/-1)-electronic parts of the one-particle Green's function are decoupled from each other and the corresponding equations can be solved separately. For a test of the method the nD-ADC(3) results for the vertical ionization transitions in C(2)H(4), CO, CS, F(2), H(2)CO, H(2)O, HF, N(2), and Ne are compared with available experimental and theoretical data including results of full configuration interaction (FCI) and coupled cluster computations. The mean error of the nD-ADC(3) ionization energies relative to the experimental and FCI results is about 0.2 eV. The nD-ADC(3) method, scaling as n(5) with the number of orbitals, requires the solution of a relatively simple Hermitian eigenvalue problem. The method renders access to ground-state properties such as dipole moments. Moreover, also one-electron properties of (N+/-1) electron states can now be studied as a consequence of a specific intermediate-state representation (ISR) formulation of the nD-ADC approach. Corresponding second-order ISR equations are presented.

Journal Article↗
PubMed2004

Theoretical study of excitations in furan: spectra and molecular dynamics.

The excitation spectra and molecular dynamics of furan associated with its low-lying excited singlet states 1A2(3s), 1B2(V), 1A1(V'), and 1B1(3p) are investigated using an ab initio quantum-dynamical approach. The ab initio results of our previous work [J. Chem. Phys. 119, 737 (2003)] on the potential energy surfaces (PES) of these states indicate that they are vibronically coupled with each other and subject to conical intersections. This should give rise to complex nonadiabatic nuclear dynamics. In the present work the dynamical problem is treated using adequate vibronic coupling models accounting for up to four coupled PES and thirteen vibrational degrees of freedom. The calculations were performed using the multiconfiguration time-dependent Hartree method for wave-packet propagation. It is found that in the low-energy region the nuclear dynamics of furan is governed mainly by vibronic coupling of the 1A2(3s) and 1B2(V) states, involving also the 1A1(V') state. These interactions are responsible for the ultrafast internal conversion from the 1B2(V) state, characterized by a transfer of the electronic population to the 1A2(3s) state on a time scale of approximately 25 fs. The calculated photoabsorption spectrum of furan is in good qualitative agreement with experimental data. Some assignments of the measured spectrum are proposed.

Journal Article↗
PubMed2004

Intermediate state representation approach to physical properties of electronically excited molecules.

Propagator methods provide a direct approach to energies and transition moments for (generalized) electronic excitations from the ground state, but they do not usually allow one to determine excited state wave functions and properties. Using a specific intermediate state representation (ISR) concept, we here show how this restriction can be overcome in the case of the algebraic-diagrammatic construction (ADC) propagator approach. In the ISR reformulation of the theory the basic ADC secular matrix is written as a representation of the Hamiltonian (or the shifted Hamiltonian) in terms of explicitly constructable states, referred to as intermediate (or ADC) states. Similar intermediate state representations can be derived for operators other than the Hamiltonian. Together with the ADC eigenvectors, the intermediate states give rise to an explicit formulation of the excited wave functions and allow one to calculate physical properties of excited states as well as transition moments for transitions between different excited states. As for the ground-state excitation energies and transition moments, the ADC excited state properties are size consistent so that the theory is suitable for applications to large systems. The established hierarchy of higher-order [ADC(n)] approximations, corresponding to systematic truncations of the IS configuration space and the perturbation-theoretical expansions of the ISR matrix elements, can readily be extended to the excited state properties. Explicit ISR matrix elements for arbitrary one-particle operators have been derived and coded at the second-order [ADC(2)] level of theory. As a first computational test of the method we have carried out ADC(2) calculations for singlet and triplet excited state dipole moments in H(2)O and HF, where comparison to full CI results can be made. The potential of the ADC(2) method is further demonstrated in an exploratory study of the excitation energies and dipole moments of the low-lying excited states of paranitroaniline. We find that four triplet states, T1-T4, and two singlet states, S1 and S2, lie (vertically) below the prominent charge transfer (CT) excitation, S3. The dipole moment of the S3 state (17.0D) is distinctly larger than that of the corresponding T3 triplet state (11.7D).

Journal Article↗
PubMed2004

Organ donation and transplantation in Brazil: university students' awareness and opinions.

This study was aimed at assessing university students' awareness and opinions about aspects of the law no. 10.221/01. This exploratory study was performed among students at the São Paulo Federal University-UNIFESP, from 2001 to July 2002, including 1284 undergraduates in the following courses: nursing, medicine, speech and language therapy, biomedicine, and ophthalmic technology. That data show that 47.7% (333) of undergraduates are aware of the kind of donation established by the new law. Among the adolescents of first and second grades, and courses, there was a difference on the awareness about the kind of donation (P =.000). Most undergraduates (57.6%, 402) agree with consented donation. However, the high percentage--35.1% (245)--that chose the alternative "I don't know" is remarkable. Results show that many undergraduates are unaware of the specifications of the technical files for transplants; only 48.3% (337) of them chose the correct answer, and 79.4% (554) do not believe that the order in the waiting list for transplants is respected. The conclusion is that it is worth emphasizing is that there are different opinions and levels of awareness among students, considering age, religion and religious practice, and course and level at school. In spite of unawareness and lack of belief in the principles of distribution of organs and tissue, most students are willing to be donors (68.2%).

Adult↗
PubMed2001

Consistent lowering of clotting factors for the treatment of acute cardiovascular syndromes and hypercoagulability: a different pathophysiological approach.

Hypercoagulability is a key contributor to acute cardiovascular syndromes and to various microcirculatory disorders. The use of heparin-mediated extracorporeal low-density lipoprotein/fibrinogen precipitation (HELP) apheresis makes a controlled, immediately effective reduction of clotting factors possible, and induces subsequent positive effects on plasma viscosity, erythrocyte aggregation, and microcirculation. Oxygen supply to an ischemic artery can thus be increased without hemodilution, qualifying the HELP system as a possible therapeutic tool in the treatment of acute cardiovascular syndromes and microcirculatory disorders.

Aged↗
PubMed2001

Lysine and polyamines are substrates for transglutamination of Rho by the Bordetella dermonecrotic toxin.

Bordetella dermonecrotic toxin (DNT) catalyzes the transglutamination of glutamine-63/61 of Rho GTPases, thereby constitutively activating Rho proteins. Here we identified second substrates for transglutamination of RhoA by DNT. The enzymatically active fragment of DNT (residues 1136 to 1451, DeltaDNT) induced the incorporation of L-[(14)C]lysine in RhoA in a concentration-dependent manner. Also, Rac and Cdc42, but not Ras, were transglutaminated with lysine by DeltaDNT. Transglutamination of the GTPase with L-lysine inhibited intrinsic and Rho-GAP-stimulated GTP hydrolysis of RhoA. In contrast to lysine, treatment of RhoA with alanine, arginine, and glutamine were not able to substitute for lysine in the transglutamination reaction. DNT increased the incorporation of L-[(14)C]lysine into embryonic bovine lung cells. Microinjection of GST-RhoA together with the enzymatically active DNT fragment into Xenopus oocytes, subsequent affinity purification of modified GST-RhoA, and mass spectrometry identified attachment of putrescine or spermidine at glutamine-63 of RhoA. A comparison of putrescine, spermidine, and lysine as substrates for DNT-induced transglutamination of RhoA revealed that lysine is a preferred second substrate at least in vitro.

Animals↗
PubMed2000

Structure and function of the ion channel ICln.

Normal function of organs and cells is tightly linked to the cytoarchitecture. Control of the cell volume is therefore vital for the organism. A widely established strategy of cells to counteract swelling is the activation of chloride and potassium channels, which leads to a net efflux of salt followed by water - a process termed regulatory volume decrease. Since there is evidence for swelling-dependent chloride channels (IClswell) being activated also during pathological processes, the identification of the molecular entity underlying IClswell is of utmost importance. Several proteins are discussed as the channel forming IClswell, i.e. phospholemman, p-glycoprotein, CLC-3 and ICln. In this review we would like to focus on the properties of ICln, a protein cloned from a Madin Darby canine kidney (MDCK) cell library whose expression in Xenopus laevis oocytes resulted in a nucleotide sensitive outwardly rectifying chloride current closely resembling the biophysical properties of IClswell.

Amino Acid Sequence↗
PubMed1999

Identification of the C-terminal part of Bordetella dermonecrotic toxin as a transglutaminase for rho GTPases.

Bordetella dermonecrotic toxin (DNT) causes the deamidation of glutamine 63 of Rho. Here we identified the region of DNT harboring the enzyme activity and compared the toxin with the cytotoxic necrotizing factor 1, which also deamidates Rho. The DNT fragment (DeltaDNT) covering amino acid residues 1136-1451 caused deamidation of RhoA at glutamine 63 as determined by mass spectrometric analysis and by the release of ammonia. In the presence of dansylcadaverine or ethylenediamine, DeltaDNT caused transglutamination of Rho. Deamidase and transglutaminase activities were blocked in the mutant proteins Cys(1292) --> Ala, His(1307) --> Ala, and Lys(1310) --> Ala of DeltaDNT. Deamidation and transglutamination induced by DeltaDNT blocked intrinsic and Rho- GTPase-activating protein-stimulated GTPase activity of RhoA. DeltaDNT deamidated and transglutaminated Rac and Cdc42 in the absence and presence of ethylenediamine, respectively. Modification of Rho proteins by DeltaDNT was nucleotide-dependent and did not occur with GTPgammaS-loaded GTPases. In contrast to cytotoxic necrotizing factor, which caused the same kinetics of ammonia release in the absence and presence of ethylenediamine, ammonia release by DeltaDNT was largely increased in the presence of ethylenediamine, indicating that DeltaDNT acts primarily as a transglutaminase.

Amino Acid Sequence↗
PubMed1999

Identification of the region of rho involved in substrate recognition by Escherichia coli cytotoxic necrotizing factor 1 (CNF1).

The Escherichia coli cytotoxic necrotizing factor 1 (CNF1) and the Bordetella dermonecrotic toxin (DNT) activate Rho GTPases by deamidation of Gln(63) of RhoA (Gln(61) of Cdc42 and Rac). In addition, both toxins possess in vitro transglutaminase activity in the presence of primary amines. Here we characterized the region of Rho essential for substrate recognition by the toxins using Rho/Ras chimeras as protein substrates. The chimeric protein Ras55Rho was deamidated or transglutaminated by CNF1. Rat pheochromocytoma PC12 cells microinjected with Ras55Rho developed formation of neurite-like structures after treatment with the CNF1 holotoxin indicating activation of the Ha-Ras chimera and Ras-like effects in intact cells. The Ras59Rho78Ras chimera protein contained the minimal Rho sequence allowing deamidation or transglutamination by CNF1. A peptide covering mainly the switch II region and consisting of amino acid residues Asp(59) through Asp(78) of RhoA was substrate for CNF1. Changes of amino acid residues Arg(68) or Leu(72) of RhoA into the corresponding residues of Ras (R68ARhoA and L72QRhoA) inhibited deamidation and transglutamination of the mutants by CNF1. In contrast to CNF1, DNT did not modify Rho/Ras chimeras or the switch II peptide (Asp(59) through Asp(78)). Glucosylation of RhoA at Thr(37) blocked deamidation by DNT but not by CNF. The data indicate that CNF1 recognizes Rho GTPases exclusively in the switch II region, whereas the substrate recognition by DNT is characterized by additional structural requirements.

Amino Acid Sequence↗
PubMed1999

Coronary risk factor management for the prevention and treatment of graft vessel disease in heart transplant patients.

There is increasing evidence that atherogenic risk factors largely contribute to the pathogenesis of graft vessel disease (GVD) after heart transplantation. Initial endothelial damage of the transplant heart derives from reperfusion ischemia during operation, repeated infections, and rejection episodes. Immunosuppressive medication considerably increases low density lipoprotein (LDL) cholesterol, lipoprotein(a), and fibrinogen blood levels, which in turn further damage the endothelium of the graft coronaries. Probably, this interplay of immunological and atherogenic factors accounts for the rapid development of GVD and its poor prognosis. The rapidity of the disease process makes it necessary to eliminate important risk factors as early and as efficiently as possible. Therefore, we studied whether heart transplant patients could benefit from a combined treatment of statins and apheresis heparin extracorporeal LDL/fibrinogen precipitation (HELP), which has already been shown to be beneficial for the treatment of advanced coronary artery disease. Such a combined treatment allows simultaneous and drastic reduction of LDL, lipoprotein(a), and fibrinogen blood levels and significantly prevented GVD. Moreover, it did not affect the prevention of rejections and infections, respectively.

Blood Component Removal↗
PubMed1998

Use of nuclear magnetic resonance imaging angiography to follow-up arterial remodeling in an animal model.

Appropriately sized arteries in small animals may be possible models for studying the remodeling process as occurs after arterial balloon injury in humans. Magnetic resonance imaging (MRI) is able to noninvasively image tissue in vivo. To date, small animal angiography models have mostly used research-dedicated instruments and resolution, which are not universally available. Experiments were carried out on a rat aorta model of remodeling in vivo (n=40). Arteries were injured by oversized balloon dilation; control arteries were uninjured. Angiography imaging was performed immediately before sacrifice with an unmodified clinical MRI unit, a 1.5 Tesla MR tomograph with a 20-cm-diameter coil. Longitudinal MRI pictures of the aorta and morphometry of tissue sections to measure luminal and arterial wall areas were analyzed with use of computer-assisted techniques. Comparison of dimensions demonstrated correlation between MRI and histology measurements of the lumen. MRI and morphometry showed a gradual increase in mean luminal area over 6 weeks following injury. The lumen increase correlated with total arterial area and thickness. In this rat aorta model, remodeling documented at histology was followed-up in vivo. The use of such clinical MRI scanners has potential to reduce animal numbers needed to follow-up the remodeling process after therapeutic intervention.

Angioplasty, Balloon↗
PubMed1997

[Work and high-risk pregnancy due to diabetes: two incompatible circumstances].

In 1991 the prevalence of diabetes was 7.6% in women in nine Brazilian state capitals. This disease now ranks among the leading causes of death in the country and is becoming an increasingly alarming public health problem. In spite of advances in the treatment of diabetes and improved obstetric care, gestational diabetes puts a pregnant woman at high risk of spontaneous abortion, ketoacidosis, hypoglycemia, hypertension, and other serious disorders. This study used life histories to investigate the relationship between health, sexuality, and work in five working women who were diabetic and pregnant and who received care at the Prenatal Care Outpatient Clinic of the San Pablo Hospital. All these women had non-insulin-dependent diabetes mellitus, were between 26 and 43 years old, and earned from US$ 150 to 375 per month for working 8-hours days, with one day off each week. Two of the women's male partners were unemployed; all of the women performed household chores during their day off. Quotations taken directly from conversations with the five participants reveal: the difficulty of caring for children and working; the sexual harassment that some of them suffered; the conflict and dissatisfaction associated with work; the myth of the natural joy of motherhood; the sexual control exercised by males; the interference of working conditions and work activities with pregnancy; and the perception that they did not have legal protection owing to employers' lack of respect for workers' rights and for the maternity protection provisions of the Federal Constitutional of Brazil. It is concluded that health policies should pay greater attention to improving the quality of life of working women, especially if they suffer from diabetes and are pregnant.

Adult↗