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Biomedical subjects

C Becker

Publications and source records attributed to C Becker.

At least 271 records · Page 15Linked to original sources
PubMed1996

Quantitative assessment of MRI lesion load in multiple sclerosis. A comparison of conventional spin-echo with fast fluid-attenuated inversion recovery.

In this study, we compared a fast fluid-attenuated inversion recovery (fast-FLAIR) sequence to conventional spin-echo (CSE) in the evaluation of brain MRI lesion loads of seven patients with clinically definite multiple sclerosis. Interleaved CSE (3000/20, 5 mm contiguous axial slices) and fast-FLAIR (9000/150/2200, 5 mm contiguous axial slices) sequences were performed on a 1.0 T machine. Lesions were counted consensually by two observers and then segmented independently by two other observers using a local thresholding technique, with subsequent manual editing in the case of poorly defined lesions. Four hundred and two lesions were detected in at least one of the two sequences: 128 were seen only on fast-FLAIR, 17 only on CSE. Forty-one lesions were larger on fast-FLAIR, while no lesion was considered larger on CSE. The numbers of periventricular (P = 0.05), cortical/subcortical (P = 0.02) and discrete (P = 0.05) lesions detected using fast-FLAIR were higher than those detected using CSE. The median lesion load was 7185 mm3 on CSE and 8418 mm3 on the fast-FLAIR, the average being 18% (range = 11.6-29%) higher on the fast-FLAIR images. Lesion contrast ratio was higher for lesions on the fast-FLAIR than on the CSE sequence (P < 0.0001). The percentages of poorly defined lesions which needed manual editing after the local thresholding technique was applied and the total time needed for the measurements were lower (P < 0.001) when fast-FLAIR images were used compared with CSE. This resulted in a reduced inter-rater coefficient of variation in measuring lesion volumes. Our data indicate that fast-FLAIR sequences are more sensitive than CSE in detecting multiple sclerosis lesion burden and that fast-FLAIR is a promising technique for natural history studies and clinical trials in multiple sclerosis.

Adult↗
PubMed1996

The full-scale PACS archive. A prerequisite for the filmless hospital.

PURPOSE: Increasing percentages of digital modalities in radiology, in particular of digital image acquisition in conventional radiography, call for digital reporting, communication, and archiving techniques. These techniques are prerequisites for the "filmless" hospital. The first 2 have been covered extensively in the literature and by vendors. However, as regards online digital image archives there are still no satisfactory concepts available in the medical field. The present paper puts forward some suggestions as to how this situation could be improved. MATERIAL AND METHODS: Analyses of radiology operations consider the prevailing PACS (picture archiving and communication system) archive concepts that use optical discs to be too small, too slow and too cumbersome to manage and therefore unable to function as comprehensive image archives for filmless hospitals. We suggest borrowing and adapting the well tested archive technologies from space research and the oil and broadcasting industries which have much higher capacities and speeds and better software interfacing possibilities. With such technologies the needs of filmless hospital operations can be met. RESULTS: A feasible concept for a transition strategy from conventional analog to digital archives is presented. Model calculations of the necessary investments and potential savings, including generous placement of viewing stations in the entire hospital, indicate amortization periods of 3.8-4.8 years. CONCLUSION: Alternative technologies for digital image archives already today make full-scale PACS for filmless hospitals technologically and conceptually feasible and financially mandatory.

Computer Systems↗
PubMed1996

Risk of traffic accidents in patients with sleep-disordered breathing: reduction with nasal CPAP.

Sleepiness whilst driving constitutes a road safety risk. Sleep-related breathing disorders are the most frequent medical cause of daytime sleepiness, and untreated patients with this condition have been shown to be at a higher risk of having accidents while driving. This study addressed the question of the extent to which treatment of sleep-disordered breathing by nasal continuous positive airway pressure (nCPAP) is related to changes in patient's accident risk. Seventy eight male patients requiring treatment of sleep-related breathing disorders with nCPAP were enrolled in the study. The protocol included a questionnaire dealing with alertness-related problems while driving, an 80 min vigilance test, and the Multiple Sleep Latency Test. These baseline evaluations were repeated after 1 year of treatment with nCPAP. Fifty nine patients completed the study. The accident rate was significantly decreased from 0.8 per 100,000 km (untreated) to 0.15 per 100,000 km with nCPAP treatment. Variables that were considered to be likely to increase accident risk (sleeping spells, fatigue, vigilance test reaction time, daytime sleep latency) also improved with treatment. We conclude that treatment of sleep-disordered breathing by nasal continuous positive airway pressure is related to reduction in patient motor vehicle accident rates, probably due to the reversal of excessive daytime sleepiness.

Accidents, Traffic↗
PubMed1996

Predictors of carbon monoxide and hydrogen cyanide exposure in smoke inhalation patients.

OBJECTIVE: A prospective study of civilian (nonfirefighter) smoke inhalation patients was carried out to test the hypotheses that: 1) absorption of carbon monoxide and hydrogen cyanide from smoke can be predicted by clinical examination and historical data; and, more specifically 2) a history of exposure to burning synthetic polymers is an important predictor of systemic cyanide levels. METHODS: The study was conducted over a three-year period at six urban hospitals. Patients with or without burns who were exposed to smoke within five hours of hospital arrival were sampled for carboxyhemoglobin, whole blood cyanide, urine cotinine and urine creatinine. Controls consisted of a smaller group of smoking status-matched, nonsmoke-exposed burn patients. ANALYSIS: Historical information was obtained on SMOKING status, FIRETYPE (structural vs other), MATERIAL burned (natural vs synthetic) and LAGTIME (from exposure to sampling). A smoke inhalation SCORE (0-10) was assigned to each case, based on physical examination findings and changes on chest X ray, and carboxyhemoglobin and cyanide levels were entered into various multivariate linear regression models. RESULTS: A total of 40 cases and 9 controls were recruited, ranging in age from 15 to 92 years. Thirty-four cases were discharged alive and six expired in-hospital. Observed carboxyhemoglobin levels ranged from 1.2% to 41.6% in cases (mean 8.6%), and from 0.5 to 7.3% in controls (mean 2.9%). Observed cyanide levels ranged from nondetectable (< 0.05 micrograms/mL) to 2.79 micrograms/mL in cases (mean 0.25 micrograms/mL), and from nondetectable to 0.11 micrograms/mL in controls (mean 0.03 micrograms/mL). Among cases, linear regression models explained up to 35% of the observed variance in carboxyhemoglobin levels (p < 0.001) and up to 48% of the variance in cyanide levels (p = 0.0001). CONCLUSIONS: SCORE was the strongest predictor of both carboxyhemoglobin and cyanide levels; LAGTIME also explained significant variance for [log-transformed] carboxyhemoglobin. Historical factors, such as FIRETYPE, MATERIAL, and SMOKING status, did not explain significant variance in most of the statistical models employed.

Adolescent↗
PubMed1995

cDNA cloning for a putative cysteine proteinase from developing seeds of soybean.

cDNA clones for a putative cysteine proteinase were isolated from developing cotyledons of soybean (Glycine max.) using PCR-based techniques. The full-length clone of 1441 bp encodes a proteinase pre-propolypeptide of 380 amino acids. It belongs to the commonly known papain family and shows the highest sequence homology (up to 53% identity) to the protein 15A, a turgor-responsive cysteine proteinase of pea, as well as to several other stress inducible proteinases. Biosynthesis of the corresponding transcripts was shown to be developmentally controlled during embryogenesis. Southern analyses revealed occurrence of one to two genes in the soybean genome.

Amino Acid Sequence↗
PubMed1995

Purification, cDNA cloning and characterization of proteinase B, an asparagine-specific endopeptidase from germinating vetch (Vicia sativa L.) seeds.

Proteinase B, an asparagine-specific endopeptidase, has been purified from germinating vetch (Vicia sativa L.) seeds. The final preparation consists of two enzymically active proteins with molecular masses of approximately 39 kDa and 37 kDa. Synthetic substrates were used to confirm cleavage specificity of the proteinase B preparation. As expected, the enzyme cleaves the substrates at the C-terminal side of Asn residues. The octapeptide ETRNGVEE was digested most efficiently. When Gly was replaced by Ile or Glu, cleavage took place with lower efficiency. Polyclonal antibodies displayed both proteins in cotyledon extracts of germinated vetch seeds. In addition, a strong cross-reacting protein band was found in cotyledon extracts of developing seeds, indicating the presence of a very similar enzyme during seed development. cDNA clones encoding proteinase B precursor have been obtained on the basis of the N-terminal amino acid sequence DDDFEGTRWAILLAGS, by means of the polymerase chain reaction. The cDNA clones contain an open reading frame of 1479 bp encoding a polypeptide of 493 amino acids. The precursor displayed 59% sequence identity to the cDNA-derived amino acid sequence of a vacuolar Asn-specific enzyme from the developing castor beam endosperm which is thought to catalyze the post-translational processing of pro-proteins into the mature forms. Proteinase B is synthesized de novo during seed germination. The results of Southern-blot analyses suggested that there are at least two genes for proteinase B.

Amino Acid Sequence↗
PubMed1995

Neurobehavioral effects of low-level methanol vapor exposure in healthy human volunteers.

Methanol-powered vehicles are being introduced in the United States as a solution to air pollution. This study assessed whether acute exposure to methanol vapor at the current industrial threshold limit value of 200 ppm for 4 hr has adverse effects on human neurobehavioral performance. Twenty-six healthy subjects (15 men, 11 women; ages 26-51 years) were exposed to methanol or water vapor for 4 hr while seated in a chamber. The subjects served as their own controls in a randomized, double-blind study design. The variables assessed were serum and urine methanol and formate levels; visual performance (color discrimination and contrast sensitivity); and neurophysiological (auditory evoked potentials) and neurobehavioral performances. Exposure to methanol increased serum concentrations and urinary excretions of methanol, but did not affect formate levels. Overall visual, neurophysiological, and neurobehavioral test outcomes were not significantly affected, unless certain between-subject variables are considered. Slight effects on P-300 amplitude and Symbol Digit testing were noted. We conclude that acute exposure of healthy people to low concentrations of methanol had little effect on these measures of neurobehavioral performance.

Administration, Inhalation↗
PubMed1995

Seroprevalence of hantavirus antibodies in Germany as determined by a new recombinant enzyme immunoassay.

In order to elucidate the epidemiological importance of hemorrhagic fever with renal syndrome in Germany, the prevalence of antibodies against hantaviruses was determined in 13,358 sera from residents of various geographic regions, 1,284 sera from occupational risk groups and 287 sera from chronic hemodialysis patients. Serological investigations were performed using a highly specific transferable solid phase enzyme immunoassay based on the recombinant nucleocapsid proteins of a Hantaan and a Puumala serotype strain. The overall antibody prevalence was found to be 1.68%. In the serum panels from western and southern Germany, it was determined to be 1.83% on average in contrast to only 0.8% in the panel from eastern Germany. An endemic focus revealing an antibody prevalence of 3.12% was detected in a low-mountain area called Suebian Alb, which is located in the federal state of Baden-Württemberg. Occupational risk groups and a group of chronic hemodialysis patients showed a significantly elevated antibody prevalence ranging from 3.3% to 10%. The Puumala serotype was found to be the prevailing virus, but the percentage of sera predominantly recognizing the Hantaan nucleocapsid protein increased towards the south and the east and was significantly elevated in dialysis patients.

Antibodies, Viral↗
PubMed1995

The precision of practice analysis results in the professions.

A practice analysis, in which an appropriate sample of professionals is asked to describe what they do in their practices, is considered an essential part of the content-related validity evidence for licensure and certification tests. This article examines the precision of estimates of the mean frequencies for categories of activities in an activity inventory administered on two occasions about 6 weeks apart. In particular, it explores the variability in estimates of the mean frequencies for categories due to the sampling of respondents, activity statements, and occasions. The results suggest that samples of 200 respondents, about 10 to 20 activity statements per category, and one occasion are adequate for estimating the mean frequency for each category.

Analysis of Variance↗
PubMed1995

[Improvement in the primary stability of the dynamic hip screw osteosynthesis in unstable, pertrochanteric femoral fractures of osteoporotic bones by a new glass ionomer cement].

Internal fixation of unstable intertrochanteric fractures of osteoporotic femurs often leads to complications, which are primarily caused by the mechanically weak bone. The aim of this study was to test whether a new glass-ionomeric cement could reinforce the weak trabecular bone of the femoral head and thus improve the preliminary stability of dynamic hip screws (DHS) used for internal fixation. As a standardized model, a intertrochanteric osteotomy was performed on eight pairs of human, female, cadaver femora; a bony defect was also created medially to diminish support of the femoral neck. To stabilize the osteotomy a 135 degrees DHS was inserted. In one femur of each pair the glass-ionomer cement was applied to see whether this would enhance stability. The elastic and irreversible deformation of the internal fixation was measured at the osteotomy level under a cyclic load of 1400 N applied to the femoral head. In both the cemented and the uncemented cases, the femoral head shifted irreversibly in the caudal direction and tilted into a varus position. Movements of the femoral head in other directions were mainly reversible and small. The irreversible movement of the femoral head was significantly larger, approximately twice as great, following uncemented DHS fixation than after cemented fixation. Most movement occurred during the first ten load cycles; higher load cycles did not increase the irreversible deformation in the cemented group, but in the uncemented group a further increase in deformation was detected. These results indicate that internal fixation of unstable intertrochanteric femoral fractures can be significantly improved by the use of cement.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

T helper target cell DNA fragmentation through a CD4-positive T suppressor cell clone inducing specific unresponsiveness.

The CD4-positive bovine serum albumin (BSA)-specific Ts cell clone BVI/5 from a CBA/J mouse tolerized to low doses of BSA induces specific unresponsiveness in the T helper (Th) cell population. Tolerance induction can be measured in vitro in proliferation assays using specific Th cell clones or antigen-primed lymph node cells (LNC) and determined in vivo by the failure to produce hapten-specific antibodies. Using the BSA-specific Th cell clone 83/1 as a target one observes in addition 51Cr-release in a 16-hr long-term assay but finds no effect in a typical 6-hr T cell cytotoxicity test. BVI/5 Ts cells do not produce interleukin-2 but otherwise express a Th1 profile. The suppression of proliferation of 83/1 Th cells is partly due to interferon-gamma (IFN-gamma). But lysis of 83/1 Th cells as well as suppression of BSA-specific LNC proliferation needs direct cell contact between BVI/5 Ts cells and their targets. Cell lysis and suppression of LNC cannot be simulated by IFN-gamma, by the combination of IFN-gamma and TNF, or by BVI/5 supernatants. Thus mediators cannot account for specific suppression by BVI/5 Ts cells in polyclonal in vitro responses from LNC and are probably not responsible for the induction of in vivo unresponsiveness. Instead the data show that BVI/5 Ts cells induce apoptosis-like DNA fragmentation in cloned BSA-specific 83/1 Th cells and in LNC from BSA-primed mice. Apoptosis can also be visualized as chromatin condensation in the LNC population. Macrophages have been excluded as targets. It can further be demonstrated that BVI/5 Ts cells express perforin and granzyme A on activation. Thus they are equipped with the effector molecules for target cell destruction. We consider BVI/5 Ts cells to be representative of a regulatory T cell inducing specific unresponsiveness in peripheral lymphoid organs.

Animals↗
PubMed1994

PCR cloning and expression analysis of cDNAs encoding cysteine proteinases from germinating seeds of Vicia sativa L.

cDNA clones encoding cysteine proteinases from cotyledons of germinated seeds of Vicia sativa L. have been obtained by means of PCR. Degenerate oligonucleotide primers were designed according to conserved amino acid regions of known cysteine proteinases. The deduced amino acid sequences of the cDNA clones encoding VSCYSPR1 and VSCYSPR2 display strong homology to cysteine proteinases of the so called papain superfamily. Northern analyses revealed developmentally regulated expression of both the mRNAs in germinating seeds. The transcripts were shown to be products of two distinct single genes, each exhibiting structural polymorphisms as exposed in few nucleotide substitutions.

Amino Acid Sequence↗
PubMed1994

Site-specific transgene insertion: an approach.

Methods to improve the production of transgenic animals are being developed. Conventional transgenesis, involving microinjection of DNA into fertilized eggs, has a number of limitations. These result from the inability to control both the site of transgene insertion and the number of gene copies inserted. The approach described seeks to overcome these problems and to allow single copy insertion of transgenes into a defined site in animal genomes. The method involves the use of embryonic stem cells, gene targeting and the FLP recombinase system.

Animals↗