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Biomedical subjects

E Mazur

Publications and source records attributed to E Mazur.

At least 19 recordsLinked to original sources
PubMed2005

Pulse energy dependence of subcellular dissection by femtosecond laser pulses.

Precise dissection of cells with ultrashort laser pulses requires a clear understanding of how the onset and extent of ablation (i.e., the removal of material) depends on pulse energy. We carried out a systematic study of the energy dependence of the plasma-mediated ablation of fluorescently-labeled subcellular structures in the cytoskeleton and nuclei of fixed endothelial cells using femtosecond, near-infrared laser pulses focused through a high-numerical aperture objective lens (1.4 NA). We find that the energy threshold for photobleaching lies between 0.9 and 1.7 nJ. By comparing the changes in fluorescence with the actual material loss determined by electron microscopy, we find that the threshold for true material ablation is about 20% higher than the photobleaching threshold. This information makes it possible to use the fluorescence to determine the onset of true material ablation without resorting to electron microscopy. We confirm the precision of this technique by severing a single microtubule without disrupting the neighboring microtubules, less than 1 micrometer away.

Actins↗
PubMed2002

Inducing and probing non-thermal transitions in semiconductors using femtosecond laser pulses.

Soon after it was discovered that intense laser pulses of nanosecond duration from a ruby laser could anneal the lattice of silicon, it was established that this so-called pulsed laser annealing is a thermal process. Although the radiation energy is transferred to the electrons, the electrons transfer their energy to the lattice on the timescale of the excitation. The electrons and the lattice remain in equilibrium and the laser simply 'heats' the solid to the melting temperature within the duration of the laser pulse. For ultrashort laser pulses in the femtosecond regime, however, thermal processes (which take several picoseconds) and equilibrium thermodynamics cannot account for the experimental data. On excitation with femtosecond laser pulses, the electrons and the lattice are driven far out of equilibrium and disordering of the lattice can occur because the interatomic forces are modified due to the excitation of a large (10% or more) fraction of the valence electrons to the conduction band. This review focuses on the nature of the non-thermal transitions in semiconductors under femtosecond laser excitation.

Electrons↗
PubMed2001

Ultrafast laser-induced phase transitions in amorphous GeSb films.

Time-resolved measurements of the spectral dielectric function reveal new information about ultrafast phase transitions induced by femtosecond laser pulses in Sb-rich amorphous GeSb films. The excitation generates a nonthermal phase within 200 fs. The dielectric function of this phase differs from that of the crystalline phase, contrary to previous suggestions of a disorder-to-order transition. The observed dielectric function is close to that of the liquid phase, indicating an ultrafast transition from the amorphous phase to a different disordered state.

Journal Article↗
PubMed2001

[The relation between Chlamydia pneumoniae infection and abdominal aortic aneurysm].

The aim of our study was to evaluate the frequency of C. pneumoniae infection in abdominal aortic aneurysm (AAA) patients by measuring C. pneumoniae specific serum IgG, IgM and IgA levels and the activation of their immune system by measuring the concentrations of IL-10, IL-12, IFN-gamma and TNF-alpha in patients' serum. Microimmunofluorescence method was applied to evaluate the level of anti-C. pneumoniae IgG, IgA and IgM. The concentrations of cytokines were evaluated using ELISA method. Serologic markers of persistent C. pneumoniae infection have been detected in 25/28 (89.3%) patients and in 6/20 (30%) healthy controls. In 40% (10/25) of patients with serologic markers of persistent C. pneumoniae infection high titers of specific IgG and IgA indicated active infection--reinfection or exacerbation of chronic infection. Mean concentrations of IL-10, IL-12, IFN-gamma and TNF-alpha indicated lack of protection against intracellular pathogens. Since all patients in this group were diagnosed as having symptomatic AAA, we suggest that active infection can exacerbate inflammation in the AAA wall and accelerate progression of the disease. In our opinion patients with active C. pneumoniae infection may be candidates to the antimicrobial treatment.

Aged↗
PubMed2000

Dorsal thoracic cord compression from a spinal angiolipoma: case report and brief comment.

Angiolipomas are benign tumors usually found in the forearms of young adults. To the best of our knowledge only 63 cases of spinal angiolipomas have been reported in the literature up until 1999 (MEDLINE 1966-1999). We report a case of a spinal angiolipoma causing dorsal cord compression in a 44-year-old woman presenting with subacute lower limb paresthesias, in the absence of sensory or motor findings, which mimicked multiple sclerosis by history. Operative intervention was curative.

Adult↗
PubMed2000

[Chronic Chlamydia pneumoniae infection in patients with asthma].

The aim of our study was to evaluate the frequency of Chlamydia pneumoniae infection (especially chronic infection) in 41 asthma patients. They have been assigned to 3 groups, according to disease severity. Control group consisted of 35 age matched healthy volunteers (without cardiac and pulmonary diseases). The levels of specific IgG, IgA and IgM in patients' serum have been estimated using indirect microimmunofluorescence. According to serologic criteria, 23(56.1%) asthma patients and 4(11.4%) healthy controls have appeared to be chronically infected with Chlamydia pneumoniae (p < 0.001). Acute Chlamydia pneumoniae infection was present in 3(7.3%) asthma patients and in 2(5.7%) healthy controls. Taking in account asthma severity, persistent Chlamydia pneumoniae infection has occurred more frequently in patients with moderate and severe asthma than in ones with mild asthma. Acute Chlamydia pneumoniae infection was present in 9.1% and 12.5% of patients with mild and severe asthma respectively.

Adult↗
PubMed2000

[Chronic Chlamydia pneumonia infection in patients with chronic obstructive pulmonary disease].

The aim of our study was to evaluate the frequency of Chlamydia pneumoniae infection (especially chronic infection) in COPD patients. Microimmunofluorescence method has been applied Chlamydia pneumoniae Micro-IF test (Labsystems) has been used. The levels of specific IgG, IgA and IgM have been estimated in patients' serum. According to serologic criteria, 64.1% of COPD patients and 20.5% of healthy controls appeared to be chronically infected with Chlamydia pneumoniae (p < 0.001). Taking in account COPD severity, persistent Chlamydia pneumoniae infection has been present in 68.2%, 57.1%, and 50% of patients with severe, moderate and mild COPD, respectively. Our study has revealed that chronic Chlamydia pneumoniae infection occurs more frequently in COPD patients than in healthy controls and in patients with severe COPD than in ones with mild and moderate disease. It is possible that persistent Chlamydia pneumoniae infection can initiate or amplify inflammatory reactions in the respiratory tract. The results suggest a need to diagnose chronic Chlamydia pneumoniae infection in COPD patients and, if confirmed, to take an attempt of antimicrobial therapy.

Case-Control Studies↗
PubMed1996

Informatics integration in a medical residency program: early experiences.

In 1992, Informatics training was integrated into the medical residency program at Norwalk Hospital. The program objective was to familiarize the residents with clinical applications of information technology that could enhance their productivity in clinical practice. In its first year, the curriculum was theory oriented. Evaluation of the program at the end of the first year led to a significant restructuring of the program format and curriculum. The trainees did not find theory to be of immediate clinical value, in the second year the program emphasis was redirected toward the development of practical skills. Next year, in 1993, 'Informatics Clinics' were initiated to develop practical Informatics skills that would be useful in a clinical setting. This approach was more successful but did not offer a complete solution. The degree to which the concepts and methods learned are clinically utilized by residents will depend upon the degree of reinforcement provided in the clinical residency years. In addition, there is a need for the development of assessment standards for the evaluation of Informatics literacy levels. In the absence of assessment standards the level of Informatics literacy in medical graduates remains undetermined Consequently, it is difficult to determine whether the training received has transformed expectations into reality.

Connecticut↗
PubMed1992

Negative cognitive errors and positive illusions for negative divorce events: predictors of children's psychological adjustment.

This study examined the relations among negative cognitive errors regarding hypothetical negative divorce events, positive illusions about those same events, actual divorce events, and psychological adjustment in 38 8- to 12-year-old children whose parents had divorced within the previous 2 years. Children's scores on a scale of negative cognitive errors (catastrophizing, overgeneralizing, and personalizing) correlated significantly with self-reported symptoms of anxiety and self-esteem, and with maternal reports of behavior problems. Children's scores on a scale measuring positive illusions (high self-regard, illusion of personal control, and optimism for the future) correlated significantly with less self-reported aggression. Both appraisal types accounted for variance in some measures of symptomatology beyond that explained by actual events. There was no significant association between children's negative cognitive errors and positive illusions. The implications of these results for theories of negative cognitive errors and of positive illusions, as well as for future research, are discussed.

Adaptation, Psychological↗
PubMed1992

[Studies of susceptibility to antibiotics in strains of E. coli isolated from urine in the years 1986-1990].

From 1986 to 1990 research was conducted on E. coli strains isolated from patients with clinical symptoms of urinary tract infection. The paper-disk-plate technique was applied to determine their susceptibility to ampicillin, carbenicillin, azlocillin, cefamandole, cefotaxime, ceftriaxone, ceftazidime, cefoperazone, amikacin, netilmicin, gentamycin, vibramycin, and colistin. According to the authors' results the efficacy of ampicillin against the examined strains is as low as 3.4%. Aminoglycosides were traditionally recommended in therapy of urinary tract infections. Our research proves amikacin and netilmicin to be more effective against E. coli than gentamycin. The third-generation cephalosporins are recommended as alternative to aminoglycosides, especially since they are proved to be non-nephrotoxic. According to the results of the authors' research ceftazidime, cefotaxime and particularly ceftriaxone show the highest activity against the used strains of E. coli.

Aminoglycosides↗
PubMed1992

[Susceptibility to nitrofurantoin, biseptol and nalidixic acid of E. coli strains isolated from urine in the years 1983-1990].

The group of microorganisms causing urinary tract infections includes the Enterobacteriaceae family, particularly E. coli, being the most commonly detected etiologic factor of the above infections. Research was conducted from 1983 to 1990 on 1102 E. coli strains isolated from patients with clinical diagnosis of urinary tract infection. Susceptibility of the bacteria to nitrofurantoin, Biseptol and nalidixic acid was determined by application of the paper-disk- plate technique. The percentage of nitrofurantoin susceptible strains during the time period of research remained on the low level of 6-20%. The susceptibility of the strains isolated from 1983 to 1987 to Biseptol was also low, 0-11%, however, in later years (1988-1990) the gradual increase of susceptibility was observed, reaching the level of 35% in 1990. The most active of the used chemotherapeutics turned out to be nalidixic acid proven to be effective against 34.3-56.3% of E. coli strains.

Escherichia coli↗