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Biomedical subjects

A Becker

Publications and source records attributed to A Becker.

At least 73 records · Page 4Linked to original sources
PubMed2002

Third-harmonic generation and self-channeling in air using high-power femtosecond laser pulses.

It is shown, both theoretically and experimentally, that during laser pulse filamentation in air an intense ultrashort third-harmonic pulse is generated forming a two-colored filament. The third-harmonic pulse maintains both its peak intensity and energy over distances much longer than the characteristic coherence length. We argue that this is due to a nonlinear phase-locking mechanism between the two pulses in the filament and is independent of the initial material wave-vector mismatch. A rich spatiotemporal propagation dynamics of the third-harmonic pulse is predicted. Potential applications of this phenomenon to other parametric processes are discussed.

Journal Article↗
PubMed2002

Prospective evaluation of a model of prediction of invasive bacterial infection risk among children with cancer, fever, and neutropenia.

A risk prediction model for invasive bacterial infection (IBI) was prospectively evaluated among children presenting with cancer, fever, and neutropenia. The model incorporated assessment of 5 previously identified risk factors: serum level of C-reactive protein (CRP) >/=90 mg/L, hypotension, identification of relapse of leukemia as the cancer type, platelet count of </=50,000 platelets/mm(3), and recent receipt of chemotherapy [16]. Children were uniformly evaluated at enrollment and were classified as having high or low risk for IBI according to a model that considers the number and type of variables present. Of the 263 febrile episodes evaluated during a 17-month period, 140 (53%) were in IBI-positive children. The sensitivity, specificity, and positive and negative predictive values of the model were 92%, 76%, 82%, and 90%, respectively. Identification of these 5 risk factors during the first 24 h of hospitalization was helpful in discriminating between children with a high or low risk for IBI.

Adolescent↗
PubMed2002

Monitoring free flaps using laser-induced fluorescence of indocyanine green: a preliminary experience.

In a prospective, clinical study, the clinical utility of indocyanine green for intraoperative monitoring of free tissue transfer was evaluated. The study comprised 20 surgical patients undergoing elective microsurgical procedures. Indocyanine green angiography was performed intraoperatively, immediately after flap inset, and the operating team was blind to the fluoremetric findings. Thereafter, postoperative monitoring was done exclusively by clinical examination (color, temperature, time for recapillarization, and bleeding after puncture). Final outcome was compared with results of perioperative indocyanine (ICG)-imaging, and classified either as total flap loss, partial flap loss, or successful tissue transplantation. A total of 2 (10%) complications was recorded, and included one partial and one total flap loss. Both complications were detected by intraoperative ICG imaging. Another case of intraoperative subclinical arterial spasm at the place of microvascular anastomosis was revealed by dynamic ICG-videography. This flap did not develop postoperative complications. In conclusion, evaluation of perfusion by ICG imaging is feasible in all kinds of microsurgical flaps, irrespective of the type of tissue. Even though not meeting all the criteria of an ideal monitoring device, significant additional information can be obtained. In this study, cases with arterial spasm, venous congestion, and regional hypoperfusion were revealed by intraoperative ICG-videography. There was a strong correlation between intraoperative findings and clinical outcome.

Angiography↗
PubMed2002

[Triclosan, a topical dermatologic agent. In vitro- and in vivo studies on the effectiveness of a new preparation in the New German Formulary].

BACKGROUND AND OBJECTIVE: Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is an antiseptic suitable for formulation as a W/O emulsion. The objective of the present study was to explore its potential utility in atopic dermatitis and prophylactic skin care following leg eczema and leg ulcer treatment. SUBJECTS AND METHODS: We performed in vitro susceptibility testing using the agar diffusion test on 602 isolates from swabs of our institution's Division of Dermatology. Additionally in an in vivo study with 15 healthy volunteers, the occlusion test and the expanded flora test were performed following the application of Hydrophobic Triclosan Cream 2% NRF (New German Formulary) 11.122. (TC) versus untreated, triclosan-free vehicle, 1% chlorhexidine digluconate solution, and ethanol 70%. RESULTS: In vitro susceptibility testing showed excellent activity against Staphylococcus aureus, Klebsiella species, and Proteus species. TC had little or no effect on Pseudomonas, beta-hemolytic streptococci, enterococci, and Candida species. In the in vivo study, TC produced a highly significant, quantitatively substantial reduction in aerobic bacterial counts versus untreated and versus vehicle. The 1% chlorhexidine digluconate solution was significantly more effective than TC in the expanded flora test. CONCLUSIONS: As S. aureus is a relevant pathogen in atopic dermatitis, and gram-negative organisms, including Klebsiella and Proteus species, as well as S. aureus play a major role in the prophylactic skin care after leg eczema and leg ulcer treatment, TC appears to be suitable for maintenance therapy in these indications.

Administration, Topical↗
PubMed2002

[Detection of coronary calcinosis with multislice spiral computerized tomography: an alternative to electron beam tomography].

Electron-beam CT (EBT) has been used for years as the gold standard to quantify coronary artery calcification as a marker of coronary atherosclerosis. With the introduction of Multi-Slice Spiral CT (MSCT) technology in 1999, EBT is now challenged in the determination of coronary calcium. The aim of this study was to determine the diagnostic accuracy of MSCT for the assessment of coronary calcium, comparing this new technique to EBT. The study population consisted of 54 male patients, aged 58 +/- 11 years with suspected coronary artery disease. For EBT, 40 axial slices (scan time = 100 ms, slice thickness = 3 mm) were acquired in one breath-hold (35 +/- 5 s) using an ECG-trigger at 80% of the RR interval. For MSCT, simultaneous acquisition of four axial slices (scan time = 250 ms, slice thickness = 2.5 mm) allowed the entire heart (40 slices) to be covered in one breath-hold (25 +/- 5 s) using a prospective ECG-trigger (R--450 ms). For quantification of coronary calcium the Agatston and the Volumetric calcium score (VCS) were applied. Mean Agatston score of the study group was calculated as 88 +/- 111 (median = 45), which is between the 25th and 75th age-corrected percentile of asymptomatic patients. For the Volumetric calcium score, number of lesions, calcium mass and density, no statistical difference was found between both imaging modalities. Agatston and Volumetric calcium score were statistically different between and within both scans. Mean variability of VCS of the two methods was calculated as 24% and was in the range of repeated EBT studies (14-44.9%). The Multi-Slice Spiral CT scanner is equivalent to EBT for the determination of coronary calcium and can, therefore, be used for calcium screening. Using a prospective ECG-trigger technique, the application of the Agatston method delivers statistically different results in comparison to EBT. With the application of the spiral mode technique, retrospective ECG-trigger and thinner slice thickness, further improvement in variability can be expected, thus allowing for follow-up studies to determine progression or regression of atherosclerosis with high accuracy.

Aged↗
PubMed2002

[Sensitivity and significance of nuclear magnetic tomography findings of finger joints in rheumatoid arthritis].

Evaluation of the sensitivity and value of magnetic resonance imaging (MRI) findings and miniarthroscopic investigations (mini-/needle-arthroscopy = MA) of metacarpophalangeal (MCP) joints in patients with rheumatoid arthritis (RA). 30 patients with RA (21 female, 9 male), disease duration 2 months to 22 years and mean disease activity score (DAS) of 3.90 (range: 2.00-7.67) were examined by MRI of the hand (MCP region) and following MA of the MCP-II joints. MRI parameters for arthritis (synovial enhancement, synovial extension, cortical alterations, joint gap width) and corresponding macroscopic items (synovial extension, synovial hyperemia and vascularity, cortical alterations) by MA, scored semiquantitatively for synovitis (graduated from 0-III degree), were correlated. Additionally, normal radiographs of the hands were performed and compared with MRI findings concerning the detection of bony lesions. Evaluation of the 30 MRI and MA examination revealed highly significant correlations (p < 0.0001) for the parameters of synovial extension (MRI/MA), cortical alterations (MRI/MA) and synovial enhancement (MRI) compared to synovial hyperemia and vascularity (MA). We found significant correlations for parameters of activity and chronicity of RA pathology as assessed by MRI and MA. The detection rate of cortical lesions by MRI was two and a half times higher than by X-ray. MRI findings of MCP-II joints compared to those of MCP III-V showed that the MCP-II joint was more strongly involved.

Adult↗
PubMed2002

Oxygen saturation in healthy newborn infants immediately after birth measured by pulse oximetry.

Pre- and postductal arterial oxygen saturation (SpO2) rates were measured in 50 healthy vaginally delivered newborn infants to establish reference values of SpO2 rates immediately after birth. We compared the SpO2 values in the pre- and postductal areas and assessed the influence of oxitocin and analgetics applied during delivery. Fifty neonates were examined by the 2nd minute (min) of life using Nellcor N-3000 pulse oximeters on the right hand and foot. Measurements were carried out until a SpO2 of 95% was achieved. Heart rates were registered simultaneously. Two min after birth the mean preductal SpO2 was 73% (44-95%) and 67% (34-93%) in the postductal region. SpO2 rates of > 95% were reached after 12 min (2-55 min) preductally and after 14 min (3-55 min) postductally. Our results demonstrate that it takes 12-14 min for healthy neonates to reach an oxygen saturation of 95% prerespectively postductal, in some cases even 55 min. All neonates were in good clinical condition and didn't require any supplemental oxygen. Additionally, we were able to show that epidural anaesthesia (PDA) during delivery increases the heart rate of the newborn infant.

Adjuvants, Anesthesia↗
PubMed2002

Duodenal necrosis as the presenting manifestation of polyarteritis nodosa.

Polyarteritis nodosa involves necrotising vasculitis of small and medium-sized arteries. Multiple organ systems are involved. A non-specific and slow course of disease is common. Gastrointestinal involvement is characterised by abdominal pain, nausea and vomiting. Bowel infarction and perforation, cholecystitis and hepatic infarction are well known complications. However, bowel infarction as the presenting symptom of the disease is rare. The case of a 20-year-old male with necrosis of the duodenum heralding polyarteritis nodosa is reported. The patient made a slow recovery after extensive abdominal surgery and a stormy course. The postoperative management and treatment of polyarteritis nodosa are discussed. A high index of suspicion and prompt multidisciplinary approach are needed in order to improve survival in these rare but potentially fatal conditions.

Adult↗
PubMed2002

[Normal values and evaluation of the German parents' version of Strengths and DIfficulties Questionnaire (SDQ): Results of a representative field study].

OBJECTIVE: The (SDQ) is a short questionnaire which addresses positive and negative behavioural attributes of children or adolescents. Being rated by parents or teachers, or as an equivalent self-report version, the 25 SDQ items were designed to include both strengths and difficulties. Although several reports have demonstrated the validity of the German SDQ, normative data have not yet been established. METHODS: In a nationwide representative field study, parent ratings were completed for 930 children and adolescents aged between 6 and 16 years. Following verification of the scale structure by factor analysis, the observed distributions of scores were used to define normal, borderline, and abnormal score ranges. Possible effects of gender, age, and social class were also investigated. RESULTS: Factor analysis yielded an exact replication of the original scales. Several associations with gender, age, and social status attained statistical significance, but cut-off scores for the five subscales remained stable in different subgroups. Age- and sex-specific bandings for the total problem score reflected small differences between homogeneous subgroups. CONCLUSIONS: After replication and confirming the original scale factors, the availability of normative data further enhances the diagnostic value of the SDQ and facilitates future validation studies. Present evidence suggests that the SDQ may serve as a useful and economical screening measure, and in many other clinical and research settings.

Adolescent↗
PubMed2002

A link between parotid salivary Ig level and recurrent respiratory infections in young Down's syndrome patients.

The purpose of the present investigation was to assess the correlation between recurrent respiratory infections and the levels of salivary Ig in a group of young Down's syndrome (DS) individuals. Twenty-three DS and 10 age- and sex-matched healthy individuals were included. DS individuals who had experienced three or more upper respiratory tract infections (n = 10) in the previous 12 months were compared to DS individuals who had not experienced recurrent respiratory infections (n = 13) and to healthy controls (n = 10). A statistically significant reduction in the Ig salivary secretion rate was recorded in the subgroup with recurrent respiratory infections. No significant differences were seen between the subgroup without recurrent respiratory infections and controls. It is suggested that the secretory immune system provides local immune protection against pathogens in the respiratory tract. Detection of salivary Ig levels may serve as a predictor of the susceptibility of DS individuals to recurrent respiratory tract infections.

Adolescent↗
PubMed2002

Why is soluble intercellular adhesion molecule-1 related to cardiovascular mortality?

Increased plasma levels of soluble adhesion molecules are associated with an increased risk of atherothrombosis. The pathophysiological mechanisms responsible for these associations are not known. The aim of the present study was to investigate the association of soluble intercellular adhesion molecule-1 (sICAM-1) concentration and risk of cardiovascular and all-cause mortality among individuals with and without type 2 diabetes. In addition, we assessed potential pathophysiological mechanisms by which sICAM-1 may promote mortality. Six hundred and thirty-one subjects taken from a general population of the middle-aged and elderly participated in this prospective cohort study. Baseline data collection was performed from 1989 to 1992; subjects were followed until 1 January 2000. Subjects who died had higher levels of sICAM-1 than those who survived (506(164) vs. 477(162) ng mL(-1), respectively). After adjustment for age, gender and glucose tolerance status, subjects with sICAM-1 levels in the upper quartile (> or =550 ng mL(-1)) had a relative risk of cardiovascular mortality of 2.05 (95% confidence interval, 1.10-3.81) compared to subjects with sICAM-1 levels in the other quartiles. Further adjustment for classical cardiovascular risk factors or indicators of (sub)clinical atherosclerosis, endothelial dysfunction, inflammation and renal function did not materially alter this relative risk. A high sICAM-1 level was more frequent in subjects with type 2 diabetes than in subjects with a normal glucose tolerance (33.3 vs. 17.8%). Individuals with a plasma concentration of sICAM-1 higher than 550 ng mL(-1) had a cardiovascular mortality risk that was twice that of individuals with a lower concentration. Classical cardiovascular risk factors (sub)clinical atherosclerosis, endothelial dysfunction and inflammation do not explain this excess risk.

Aged↗
PubMed2002

Intraoperative evaluation of skin-flap viability using laser-induced fluorescence of indocyanine green.

Laser-induced fluorescence of indocyanine green (ICG) is a new method for evaluating skin perfusion, which is superior to conventional fluorescein angiography. In a prospective clinical study ICG fluorescence video-angiography was used for the intraoperative evaluation of skin-flap perfusion. The results of ICG imaging were compared with clinical outcome 1 week postoperatively. Intraoperative ICG filling defects were always associated with delayed wound healing. In 50% of the patients, the regions of sloughing and epitheliolysis corresponded accurately to the regions of dye-filling deficits. All of the flaps without ICG filling defects healed primarily. These results suggest that ICG fluorescence is a sensitive tool for assessing nutritive blood flow in pedicled skin flaps with and without an axial vessel. Future clinical studies are required to establish critical threshold fluorescence indices that correlate with skin viability in the postoperative course.

Adult↗
PubMed2002

Inhibition of lipase activity in antibiotic-resistant propionibacterium acnes strains.

BACKGROUND AND OBJECTIVE: Erythromycin-sensitive and/or clindamycin-sensitive strains of Propionibacterium acnes show a reduced lipase production at levels below the minimal growth-inhibitory concentration (MIC). The objective of this study was to determine whether erythromycin and clindamycin concentrations far below the MIC inhibit lipase production in P. acnes strains resistant to these antibiotics. METHODS: Of 42 P. acnes strains, 10 showed an MIC >256 micro g/ml for erythromycin. Two strains showed MICs of 0.19 and 0.25 micro g/ml, while the MIC of the remaining strains was 256 micro g/ml were also tested for lipase inhibition by clindamycin. While this method fails to differentiate between inhibition of lipase production and inhibition of lipase activity, the absence of inhibition of lipase activity rules out inhibition of lipase production. RESULTS: Inhibition of lipolysis by sub-MIC concentrations was demonstrated only for clindamycin in 3 P. acnes strains. However, lipase inhibition was seen only at the dilution level immediately below the MIC. CONCLUSIONS: Resistant P. acnes strains with high erythromycin and/or clindamycin MICs can be ruled out to show in vitro inhibition of lipase production at antibiotic concentrations far below the MIC.

Acne Vulgaris↗
PubMed2002

Severe impairment of secretory Ig production in parotid saliva of Down Syndrome individuals.

Infections associated with Down Syndrome (DS) are prevalent in the mucosal-gastrointestinal and respiratory systems, for reasons that are uncertain. The purpose of the present study was to assess the levels of parotid salivary immunoglobulins (Ig) in a group of DS individuals as a possible factor in the susceptibility of mucosal surfaces to infections. Twenty-nine DS and 10 age- and sex-matched healthy individuals were included. Salivary flow rate and IgA, IgG, and IgM concentrations were recorded. The secretion rates of IgA and IgG were diminished by 83% (p < 0.001) and 75% (p = 0.05), respectively, whereas the secretion rate of IgM was not statistically significantly lower. Analysis of the data suggests that DS individuals are immunodeficient in the humoral mucosal immune response. This may explain, in part, the high incidence of recurrent infections in target organs of the secretory immune system in DS subjects.

Adolescent↗
PubMed2001

A novel MADS-box gene subfamily with a sister-group relationship to class B floral homeotic genes.

Class B floral homeotic genes specify the identity of petals and stamens during the development of angiosperm flowers. Recently, putative orthologs of these genes have been identified in different gymnosperms. Together, these genes constitute a clade, termed B genes. Here we report that diverse seed plants also contain members of a hitherto unknown sister clade of the B genes, termed B(sister) (B(s)) genes. We have isolated members of the B(s) clade from the gymnosperm Gnetum gnemon, the monocotyledonous angiosperm Zea mays and the eudicots Arabidopsis thaliana and Antirrhinum majus. In addition, MADS-box genes from the basal angiosperm Asarum europaeum and the eudicot Petunia hybrida were identified as B(s) genes. Comprehensive expression studies revealed that B(s) genes are mainly transcribed in female reproductive organs (ovules and carpel walls). This is in clear contrast to the B genes, which are predominantly expressed in male reproductive organs (and in angiosperm petals). Our data suggest that the B(s) genes played an important role during the evolution of the reproductive structures in seed plants. The establishment of distinct B and B(s) gene lineages after duplication of an ancestral gene may have accompanied the evolution of male microsporophylls and female megasporophylls 400-300 million years ago. During flower evolution, expression of B(s) genes diversified, but the focus of expression remained in female reproductive organs. Our findings imply that a clade of highly conserved close relatives of class B floral homeotic genes has been completely overlooked until recently and awaits further evaluation of its developmental and evolutionary importance. Electronic supplementary material to this paper can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00438-001-0615-8.

Amino Acid Sequence↗
PubMed2001

Functional and molecular analysis of transient voltage-dependent K+ currents in rat hippocampal granule cells.

1. We have investigated voltage-dependent outward K+ currents of dentate granule cells (DGCs) in acute brain slices from young and adult rats using nucleated and outside-out patch recordings. 2. In adult DGCs, the outward current pattern was dominated by a transient K+ current component. One portion of this current (approximately 60%) was blocked by micromolar concentrations of tetraethylammonium (TEA; IC50 42 microM) and BDS-I, a specific blocker of Kv3.4 subunits (2.5 microM). A second component was insensitive to tetraethylammonium (10 mM) and BDS-I. The transient outward current could be completely blocked by 4-aminopyridine (IC50 296 microM). 3. The TEA- and BDS-I-sensitive and the TEA-resistant current components were isolated pharmacologically. The current component that was blocked by BDS-I and TEA showed a depolarized threshold of activation (approximately -30 mV) reminiscent of Kv3.4 subunits, while the current component resistant to TEA activated at more hyperpolarized potentials (approximately -60 mV). 4. In nucleated patches obtained by placing the patch pipette adjacent to the apical dendrite, only small Na+ currents and small BDS-I-sensitive transient currents were detected. Nucleated patches obtained from either the cell soma (see above) or the axon hillock showed significantly larger amplitude Na+ currents as well as larger BDS-I-sensitive currents, indicating that this current was predominantly localized within the axosomatic compartment. This result was in good agreement with the distribution of Kv3.4 protein as determined by immunohistochemistry. 5. Current-clamp as well as mock action potential-clamp experiments revealed that the BDS-sensitive current component contributes to action potential repolarization. 6. A comparison of the two age groups (4-10 days and 60-100 days) revealed a marked developmental up-regulation of the BDS-I-sensitive component. These functional changes are paralleled by a developmental increase in Kv3.4 mRNA expression determined by quantitative real-time RT-PCR, as well as a pronounced up-regulation of Kv3.4 on the protein level determined by immunohistochemistry. 7. These functional and molecular results argue that Kv3.4 channels located predominantly in the axosomatic compartment underlie a transient K+ current in adult DGCs, and that these channels are functionally important for regulating spike repolarization. The marked developmental regulation suggests an important role of Kv3.4 in neuronal maturation.

Animals↗