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Biomedical subjects

A Becker

Publications and source records attributed to A Becker.

At least 127 records · Page 7Linked to original sources
PubMed2001

Prediction of shock in febrile medical patients with a clinical infection.

OBJECTIVE: Shock in the course of fever is likely caused by septic shock. Because septic shock carries a high mortality rate, early recognition could benefit the patient. We tried to predict the development of shock in medical patients with fever and a clinical infection, on the basis of clinical and microbiological information, and to evaluate the role therein of systemic inflammatory response syndrome (SIRS) criteria: abnormal body temperature, tachycardia, tachypnea, and abnormal white blood cell counts. DESIGN: Prospective observational study. SETTING: Department of Internal Medicine at a university hospital. PATIENTS: Patients were 212 consecutive medical patients with newly onset fever (temperature, >38.0 degrees C axillary or >38.3 degrees C rectally) and a clinical source of infection. MEASUREMENTS AND MAIN RESULTS: Of the 212 patients enrolled, 14 developed shock (i.e., a decrease in systolic arterial blood pressure of >40 mm Hg) during a maximum follow-up period of 7 days after inclusion. In univariate analyses, advanced age, prior urogenital disease, an abdominal source, nosocomial infections, and bacteremia predisposed patients to shock (p < .05). For clinical variables, obtained daily for 2 days after inclusion, a low performance (p < .001), the peak respiratory rate (p < .05), the peak heart rate (p < .05), the nadir score on the Glasgow Coma Scale (p < .005), the peak and nadir white blood cell counts (p < .005), and the nadir albumin (p < .01) and peak creatinine concentrations in blood (p < .001) predicted shock development. In multivariate analysis, the presence of bacteremia, the peak respiratory rate, the nadir Glasgow Coma Scale score, and the peak white blood cell count positively and the peak erythrocyte sedimentation rate negatively contributed to prediction of shock development. In contrast, SIRS had less predictive value, mainly because of lack of predictive value of peak heart rate and temperature in multivariate models. CONCLUSION: In febrile medical patients with a clinical infection, the development of shock involves an interaction between circulating microbial products and the host response, which can be recognized clinically by variables easily obtained at the bedside and partly different from the set used to define SIRS.

Adolescent↗
PubMed2001

Near-infrared fluorescent dyes for enhanced contrast in optical mammography: phantom experiments.

Optical mammography with near-infrared (NIR) light using time-domain, frequency-domain, or continuous-wave techniques is a novel imaging modality to locate human breast tumors. By investigating excised specimens of normal and diseased mamma tissue we were able to demonstrate that differences in their scattering properties are a poor predictive parameter for normal and diseased mamma tissue. This paper describes the application of a NIR dye to improve the differentiation between breast tumors and normal tissue in a rat model. The NIR dye furnished a high tumor-to-tissue contrast ratio (6:1) in fluorescence images. Furthermore, this dye was used to develop liquid scattering phantoms with absorbing and fluorescent inhomogeneities. Using frequency-domain and time-domain instrumentation these inhomogeneities were localized at sufficient contrast by their increased absorption and fluorescence. Contrast between inhomogeneities and surrounding medium could be improved by combining fluorescence and transmittance images.

Breast Neoplasms↗
PubMed2001

The molecular weight distribution of succinoglycan produced by Sinorhizobium meliloti is influenced by specific tyrosine phosphorylation and ATPase activity of the cytoplasmic domain of the ExoP protein.

It is thought that in the gram-negative soil bacterium Sinorhizobium meliloti the protein ExoP is involved in biosynthesis of the acidic exopolysaccharide succinoglycan (EPS I). The amounts and compositions of EPS I produced by mutants expressing ExoP proteins characterized by specific amino acid substitutions in the C-terminal cytoplasmic domain were analyzed. The cytoplasmic domain of the ExoP protein was shown to have ATPase activity. Mutations in the highly conserved Walker A ATP-binding motif prevented ATPase activity of the ExoP protein. Phenotypically, these mutations resulted in much lower levels of succinoglycan which consisted only of monomers of the octasaccharide repeating unit. The ExoP protein has similarities to proteins with autophosphorylating protein tyrosine kinase activity. We found that ExoP was phosphorylated on tyrosine and that site-directed mutagenesis of specific tyrosine residues in the cytoplasmic domain of ExoP resulted in an altered ratio of low-molecular-weight succinoglycan to high-molecular-weight succinoglycan.

Adenosine Triphosphatases↗
PubMed2001

Osteoporosis screening in systemic lupus erythematosus: impact of disease duration and organ damage.

The aim of the present study was to assess the effects of disease severity and demonstrable organ damage as risk factors for the development of osteoporosis in systemic lupus erythematosus (SLE). Sixty-four SLE patients were included. Mean disease duration was 7.7 +/- 5.7 y. Thirty-two patients had persistent organ damage, defined as SLICC-ACR damage score > or = 1. Disease activity measured by SLAM-2 ranged from 3 to 27. Bone mineral density (BMD) measurements were performed with dual X-ray absorptiometry. In addition, biochemical markers of bone metabolism were studied. BMD was inversely correlated with disease duration, damage score and cumulative glucocorticoid intake, but no correlation was found for current glucocortioid use or with markers of bone metabolism. In a multivariate analysis, body weight, disease duration and damage index fitted best for the prediction of BMD at both lumbar spine and femoral neck. Seven out of 64 patients had osteoporosis according to WHO criteria. In conclusion, severe osteoporosis is uncommon in lupus patients. Disease activity and severity were no major risk factors for loss of BMD in this study, but persistent non-bone-related organ damage was significantly linked to the presence of osteoporosis measured as decreased BMD. Our data suggest that, in addition to patients receiving glucocorticoids, patients with an SLICC-ACR > or = 1 or a disease duration > or = 7 y might benefit from regular monitoring of BMD as secondary prevention of damage.

Adult↗
PubMed2001

[Association between elevated serum VEGF and polarographically measured tumor hypoxia in head and neck carcinomas].

PURPOSE: Clinical investigation of a potential relationship between VEGF concentration in serum (sVEGF) and polarographically measured tumor oxygenation in patients with squamous cell carcinoma of the head and neck (SCCHN). PATIENTS AND METHODS: In 56 patients with SCCHN we estimated the classical tumor parameters, the sVEGF concentration (immunoassay) and the tumor oxygenation (Eppendorf pO2 histograph). The platelet count and the tumor volume were evaluated simultaneously. RESULTS: In a unifactorial analysis the total volume (132 cm3 vs. 38 cm3), the hypoxic subvolume (HSV = total volume multiplied with the relative frequency of values < or = 5 mm Hg/63 cm3 vs. 10 cm3) and the platelet count (380 10(9)/l vs. 271 10(9)/l) were significantly higher in the patient group with a sVEGF level > 707 pg/ml compared to the group with a sVEGF below this threshold. The multifactorial analysis confirmed significant effects for the hypoxic subvolume and the platelet count. Regarding hypoxic subvolume and sVEGF as continuous parameters a significantly positive correlation was found. This correlation remained somewhat weaker but significant after inclusion of the platelet count as covariate. CONCLUSION: On base of our data a clinical association between elevated sVEGF and polarographically measured tumor hypoxia could be confirmed. This was possible considering not only the relative grade of hypoxia but also the absolute amount of hypoxic regions. The VEGF released from platelets during blood clotting influences the sVEGF level essentially, however, the hypoxia effect was not completely deleted. Due to the platelet effect an estimation of sVEGF is not able to substitute polarographical measurement of tumor pO2. Therefore in an ongoing study we investigate whether VEGF values estimated in plasma are better correlated with the polarographically measured tumor pO2 than serum VEGF levels.

Adult↗
PubMed2001

Controversies and challenges of exercise-induced bronchoconstriction and their implications for children.

The association of exercise with hyperresponsiveness and bronchoconstriction of the airways has been well-recognized. Exercise may be the sole trigger or one of many triggers in patients with asthma. Although it is clear that asthma and the symptoms brought about by exercise are closely intertwined, the pathophysiology underlying this process is not well-understood. Recent studies on the epidemiology of the disease have provided insights into the processes leading to exercise-induced bronchoconstriction, with particular significance for children with asthma.

Adolescent↗
PubMed2001

[The orthodontic treatment of children with disabilities].

Due to the medical progress in the past decades, the life expectancy and quality of the physically and/or mentally disabled children have been much improved. While this has facilitated their entry into society, it has also created greater demands on our profession, from those who care for them. A displeasing dental appearance may have a significant emotional impact on an individual's well being and can bias judgments of social acceptability, ability and personality. Gross misplacement of the teeth occurs more often and with much greater severity in the disabled child than in the general population. The increased concern for facial appearance and oral functions has generated an increased demand for orthodontic treatment, but the difficulties imposed by the handicapping conditions have made many practitioners believe that these patients are not amenable to treatment. At the Center for the Treatment of Craniofacial Anomalies in the Orthodontic Department of the Hadassah School of Dental Medicine, Jerusalem we have been treating children with disabilities for several years. An investigation of the referral patterns of our patients has revealed ignorance of dentists, physicians and social workers of what can and may be done to improve the dental and facial appearance of these children. This finding was the principle reason for this article, in which we will show how successful delivery of treatment is possible for many of the disabled.

Child↗
PubMed2001

MADS-box genes are involved in floral development and evolution.

MADS-box genes encode transcription factors in all eukaryotic organisms thus far studied. Plant MADS-box proteins contain a DNA-binding (M), an intervening (I), a Keratin-like (K) and a C-terminal C-domain, thus plant MADS-box proteins are of the MIKC type. In higher plants most of the well-characterized genes are involved in floral development. They control the transition from vegetative to generative growth and determine inflorescence meristem identity. They specify floral organ identity as outlined in the ABC model of floral development. Moreover, in Antirrhinum majus the MADS-box gene products DEF/GLO and PLE control cell proliferation in the developing flower bud. In this species the DEF/GLO and the SQUA proteins form a ternary complex which determines the overall "Bauplan" of the flower. Phylogenetic reconstructions of MADS-box sequences obtained from ferns, gymnosperms and higher eudicots reveal that, although ferns possess already MIKC type genes, these are not orthologous to the well characterized MADS-box genes from gymnosperms or angiosperms. Putative orthologs of floral homeotic B- and C-function genes have been identified in different gymnosperms suggesting that these genes evolved some 300-400 million years ago. Both gymnosperms and angiosperms also contain a hitherto unknown sister clade of the B-genes, which we termed Bsister. A novel hypothesis will be described suggesting that B and Bsister might be involved in sex determination of male and female reproductive organs, respectively.

Evolution, Molecular↗
PubMed2000

Reverse methionine biosynthesis from S-adenosylmethionine in eukaryotic cells.

The intracellular ratio between methionine and its activated form S-adenosylmethionine (AdoMet) is of crucial importance for the one-carbon metabolism. AdoMet recycling into methionine was believed to be largely achieved through the methyl and the thiomethyladenosine cycles. We show here that in yeast, AdoMet recycling actually occurs mainly through the direct AdoMet-dependent remethylation of homocysteine. Compelling evidences supporting this result were obtained owing to the identification and functional characterization of two new genes, SAM4 and MHT1, that encode the yeast AdoMet-homocysteine methyltransferase and S-methylmethionine-homocysteine methyltransferase, respectively. Homologs of the Sam4 and Mht1 proteins exist in other eucaryotes, indicating that such enzymes would be universal and not restricted to the bacterial or fungal kingdoms. New pathways for AdoMet or S-methylmethionine-dependent methionine synthesis are presented.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2000

Suppressed molecular ionization for a class of diatomics in intense femtosecond laser fields

It is shown that the puzzling experimental observation of suppressed molecular ionization, in intense laser fields, of O2, and its absence in N2, is a symmetry induced dynamical effect. More generally, it is predicted that the ionization signal of the class of homonuclear diatomic molecules having valence orbitals with an antibonding symmetry (e.g., sigma(u), pi(g)) would be suppressed, but not those with a bonding symmetry (e.g., sigma(g), pi(u)). The suppression effect can be visualized as due to an effective destructive interference between the two subwaves of the ionizing electron emerging from the two atomic centers.

Journal Article↗
PubMed2000

Preconditioning-induced neuroprotection is mediated by reactive oxygen species.

The current study was performed to determine the role of reactive oxygen species (ROS) in preconditioning against different forms of neuronal damage. Primary cultures of chick embryonic neurons were treated with either FeSO(4) (100 microM; 15 min) to generate hydroxyl radicals or xanthine/xanthinoxidase (10 microM/0.5 mU ml(-1); 15 min; =X/XO (pre)) to produce superoxide radicals. Both stimuli moderately enhanced ROS formation as measured by fluorescence microscopy. This preconditioning significantly protected the neurons against subsequent glutamate (1 mM)-induced excitotoxic damage, staurosporine (200 nM)-induced neuronal apoptosis and oxidative damage caused by exposure to xanthine/xanthinoxidase (500 microM/5 mU ml(-1); 1 h; =X/XO (dam)). The antioxidants vitamin E (10 microM) and 2-OH-estradiol (1 microM), present during the 15-min preconditioning period, completely abolished the protective effect of X/XO (pre). Furthermore, glutamate, staurosporine or X/XO (dam) markedly enhanced oxygen radical formation. Preceding preconditioning by mild ROS stimulation with X/XO (pre) or Fe(2+) reduced this oxygen radical burst. Again, the effect of X/XO (pre) could be blocked by coadministration of vitamin E or 2-OH-estradiol. However, the FeSO(4)-mediated preconditioning was not abolished by the radical scavengers. To address this phenomenon, the effect of vitamin E and 2-OH-estradiol on Fe(2+)- and X/XO (pre)-induced ROS formation kinetics within the 15 min of preconditioning was monitored. The moderate rise of intracellular ROS content during preconditioning was only reduced permanently by the antioxidants, when the neurons were treated with X/XO (pre), but not when Fe(2+) was used. Thus, an immediate and constant radical scavenging seems to be indispensable to abolish the ROS-induced neuronal preconditioning. The current results indicate that preconditioning by moderate ROS-stimulation protects cultured neurons against different damaging agents and prevents against the subsequent massive oxygen radical formation.

Animals↗
PubMed2000

Interpretation of momentum distribution of recoil ions from laser induced nonsequential double ionization

We show that the recently reported momentum distribution of recoil ions from laser induced nonsequential double ionization can be interpreted as a combined effect of interelectron correlation and final state field interaction ("Volkov dressing") of the two outgoing electrons. We also find a cutoff formula for the recoil momentum that gives the maximum momenta observed in the experiments.

Journal Article↗
PubMed2000

Lack of expression of long-term potentiation in the dentate gyrus but not in the CA1 region of the hippocampus of mu-opioid receptor-deficient mice.

The possible involvement of the mu-opioid receptor subtype in mechanisms of long-term potentiation (LTP) of the lateral perforant pathway to the dentate gyrus neurons, as well as of the Schaffer collateral-commissural input of CA1 neurons, was investigated using mu-opioid receptor-deficient mutant mice. In transversal hippocampal slices from mice lacking the mu-opioid receptor (MOR) only a short potentiation in the dentate gyrus after tetanization of the lateral perforant pathway was found. In contrast, the loss of the mu-opioid receptor in the CA1 region did not affect the potentiation of the field potentials induced by tetanization of the Schaffer collaterals. In parallel experiments, the application of 10 microM of the selective MOR-antagonist, funaltrexamine, decreased LTP in the dentate gyrus of wild-type mice but again did not alter the potentiation of the field potentials in the CA1. The loss of MOR-binding in the hippocampus was accompanied by a reduction in D2-binding sites indicating a possible compensatory role of the dopaminergic system. The D1- and glutamate binding was not affected. These observations confirm earlier results with pharmacological blockade of opioid receptors in the dentate gyrus and demonstrate an essential role of MOR activation for the generation of LTP in the dentate gyrus of the mouse but not necessarily in the CA1 region.

Action Potentials↗
PubMed2000

Severe anemia is associated with poor tumor oxygenation in head and neck squamous cell carcinomas.

PURPOSE: To investigate the relationship between tumor oxygenation and the blood hemoglobin (Hb) concentration in patients with squamous cell carcinoma of the head and neck (SCCHN). METHODS AND MATERIALS: A total of 133 patients with SCCHN underwent pretreatment polarographic pO2 measurements of their tumors. In 66 patients measurements were also made in sternocleidomastoid muscles. The patients were divided into three groups according to their Hb concentration-severe anemia (Hb < 11.0 g/dl), mild anemia (female: Hb 11.0-11.9 g/dl; male: Hb 11.0-12.9 g/dl), and normal Hb concentration (female: Hb > or =12.0 g/dl; male: > or =13.0 g/dl). RESULTS: No significant difference in tumor oxygenation could be detected between mildly anemic patients and patients with a normal Hb level. However, the tumor oxygenation in the severely anemic group was significantly below that of each of the other two groups (p < 0.0001). There was no significant difference between the Hb groups in oxygenation of sternocleidomastoid muscles. In a multivariate analysis including Hb group, tumor volume, smoking habits, gender, T-stage, N-stage, and histologic grade a Hb level < 11 g/dl was found to be the strongest predictor for a poor tumor oxygenation. Smoking also had a marginal influence on median pO2. CONCLUSION: Our data suggest that a low Hb concentration and cigarette smoking contribute to inadequate oxygenation of SCCHN and thus for increased radioresistance. Consequently, Hb correction and abstinence from smoking may significantly improve tumor oxygenation.

Anemia↗
PubMed2000

[Prevention of venous thromboembolism in a non-surgical medical ward. Proposed indications for low molecular weight heparin].

OBJECTIVE: The efficiency of venous thromboembolism prophylaxis with low molecular weight heparins (LMWH) has not been established in non surgical patients, so their official preventive use has been limited in France since 1995 to surgery. However, a survey conducted in 5 university hospitals in non surgical patients showed that 21-29% of patients still received a LMWH prescription. It seemed necessary to define the medical conditions for which the practical use of these heparins would be justified. We contacted external experts to obtain a consensus by using the Delphi method. METHODS: The Delphi method, created by the "Rand Corporation" in the USA and used in medicine since the nineteen seventies, is based on a light logistic, with questionnaires been sent by mail with a feed-back report A total of 48 experts were chosen by local staff teams in the 5 hospitals. For the 3 rounds, from March to October 1998, questions were devised by a multicentred staff team. RESULTS: Among the 48 experts contacted, 32 completed the 3 questionnaires, 7 of them did for 2, and 43 did for at least one questionnaire. The experts first defined a list of 12 risk or high risk situations and 11 aggravating factors. For any high risk situation, prescription is justified. For other cases, 2 risk situations are required, or one risk situation with at least 2 aggravating factors, to justify a prescription. If no risk situation is present, prescription is, according to experts, usually not justified. CONCLUSION: The maximal agreement defines the situations in which one use of low molecular weight heparins is proposed to prevent deep venous thrombosis in non surgical inpatients, in most current hospital situations and for more than 24 hours of hospitalization. Clinical trials are needed, to validate their effectiveness and define the optimal dose in these indications. To date, epidemiological studies should be conducted to evaluate the experts proposals by estimating risk factors for deep venous thrombosis.

Double-Blind Method↗
PubMed2000

A randomized controlled study on the effectiveness of a multifaceted intervention program in the primary prevention of asthma in high-risk infants.

BACKGROUND: The prevalence of asthma has increased in developed countries in the past 2 decades. The effectiveness of intervention measures on the primary prevention of asthma has not been well studied. OBJECTIVE: To assess the effectiveness of a multifaceted intervention program in the primary prevention of asthma in high-risk infants (in this study, infants are defined as persons from birth to the age of 1 year). DESIGN: Prospective, prenatally randomized, controlled study with follow-up through the age of 1 year. SETTING: University hospital-based settings at 2 Canadian centers: Vancouver, British Columbia, and Winnipeg, Manitoba. PARTICIPANTS: A total of 545 high-risk infants (at least 1 first-degree relative with asthma or 2 first-degree relatives with other IgE-mediated allergic diseases) identified before birth. INTERVENTIONS: Avoidance of house dust mite and pet allergens and environmental tobacco smoke, encouragement of breastfeeding, and supplementation with a partially hydrolyzed formula. MAIN OUTCOME MEASURES: Probable or possible asthma, rhinitis without apparent colds, and a prick skin test result positive for common inhalant allergens. RESULTS: Thirty-eight (15.1%) of the 251 infants available for assessment in the intervention group and 49 (20.2%) of the 242 infants available for assessment in the control group fulfilled the criteria for possible or probable asthma (adjusted relative risk, 0.66; 90% confidence interval, 0.44-0.98). Also, 16.7% of the infants in the intervention group and 27.3% of the infants in the control group developed rhinitis without colds (adjusted relative risk, 0.51; 90% confidence interval, 0.35-0.74). The incidence of positive skin test results to 1 or more inhalant allergens was similar in both groups (4.4% in the intervention group and 4.6% in the control group). CONCLUSIONS: Our multifaceted intervention program resulted in a modest but significant (P= .04) reduction in the risk of possible or probable asthma and rhinitis without apparent colds at the age of 12 months in high-risk infants. In the absence of a validated definition of asthma at the age of 12 months, follow-up studies are needed to determine the effectiveness of the intervention program in the primary prevention of asthma in high-risk infants.

Asthma↗