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Biomedical subjects

J Fabian

Publications and source records attributed to J Fabian.

At least 55 records · Page 3Linked to original sources
PubMed1996

Interventional cardiology in Europe 1993. Working Group on Coronary Circulation of the European Society of Cardiology.

An annual survey on cardiac interventions in Europe is performed by the working group on Coronary Circulation of the European Society of Cardiology with the help of the national societies of cardiology. A questionnaire about cardiac interventions in 1993 was mailed to a representative of the national societies of 35 members of the European Society of Cardiology. The data collection of coronary interventions was delayed by slow backreporting and from 10 of the 35 national members data were missing or grossly incomplete. They were excluded from the analysis. CORONARY ANGIOGRAPHY: A total of 756,822 coronary angiograms were reported resulting in an incidence of 1146 +/- 1024 per 10(6) inhabitants, ranging from 24 (Romania) to 3499 (Germany). This represents an increase of 12% compared to 1992. Germany (279,882 cases), France (157,237), the United Kingdom (77,000), Italy (44,934) and Spain (37,591) registered 79% of all the coronary angiograms performed. PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY: A total of 183,728 percutaneous transluminal coronary angioplasty cases were reported in 1993, 24% more than in 1992. On average, they accounted for 18 +/- 7% (range 8 (Romania) to 35% (Sweden) of the coronary angiograms. Most of these percutaneous transluminal coronary angioplasties (82%) were confined to a single vessel. In 13% only, percutaneous transluminal coronary angioplasty took place immediately after the diagnostic study. Adjusted per capita. Germany ranks first with 873 percutaneous transluminal coronary angioplasties per 10(6) inhabitants, followed by France (737), Holland (725), Belgium (713), and Switzerland (665). The European mean of percutaneous transluminal coronary angioplasties per 10(6) inhabitants was 270 +/- 279, representing an increase of 14% compared with 1992. A major in-hospital complication was reported in 3.8% of the patients undergoing percutaneous transluminal coronary angioplasty: 0.6% hospital deaths, 1.5% emergency coronary artery bypass grafting, and 1.7% myocardial infarctions. NEW DEVICES: In 1993 stents were implanted in 6444 patients (3.5% of all percutaneous transluminal coronary angioplasty patients), equally distributed between bail-out situations (53%) and elective procedures. The 14 stent implanting countries showed a mean increase in incidence of coronary stenting of 53% compared with 1992. Other interventional devices were applied in 7045 cases, 3.8% of all percutaneous transluminal coronary angioplasty cases. Coronary ultrasound (2194 cases) and coronary angioscopy (380 cases) were performed infrequently. NON-CORONARY INTERVENTIONS: Valvuloplasties were most frequently performed non-coronary interventions European countries performed more than 300 valvuloplasties each in 1993. Most of them were mitral valvuloplasties in southern countries. CONCLUSIONS: Although partial backreporting might conclusions, several findings of this survey are noteworthy for the participating countries: The number of percutaneous taneous transluminal coronary angioplasties is universally increasing. There is an extremely wide range of coronary angiography and percutaneous translumina, coronary angioplasties performed per population. The most common additional procedure is a stent implantation while other new devices are only rarely applied. Mitral valvuloplasty is the most frequently performed non-coronary intervention.

Angioplasty, Balloon, Coronary↗
PubMed1996

Restoring forces assessed with left atrial pressure clamps.

A negative pressure (P) in the fully relaxed left ventricle (LV) indicates the presence of restoring forces generated during contraction. To assess restoring forces in the intact LV under physiological filling conditions, a servomotor system was used in anesthetized open-chest dogs (n = 8) to produce nonfilling diastoles by left atrial pressure (LAP) clamping during systole such that LAP was less than left ventricular pressure (LVP) during the subsequent diastole. Steady-state LV end-diastolic pressure (EDP) was varied by volume infusion from 4.0 +/- 1.5 (+/-SD) to 12.8 +/- 2.1 mmHg. The corresponding fully relaxed LVPs increased from -2.1 +/- 1.9 to 1.1 +/- 3.2 mmHg, P < 0.001. LAP clamping increased the rate of LVP fall by 34 +/- 28% (P < 0.001) during 10 ms after the LVP dropped below the level of the LVP-LAP crossover of the preceding normal beat. During clamped beats, two-dimensional echo revealed substantial downward displacement of the mitral valve (MV) leaflets despite the reversed LA-LV gradient and absence of filling. Thus 1) restoring forces are present at low physiological EDP but absent at high physiological EDP; 2) filling retards the rate of fall of LVP; 3) even in the absence of filling, the process of LV relaxation facilitates MV opening.

Animals↗
PubMed1996

Estimating local-area needs for psychiatric care: a case study.

BACKGROUND: Different approaches to estimating local catchment-area needs for psychiatric services are illustrated and compared. METHOD: Data from an epidemiological morbidity survey of a random sample of 496 adults were available, as were actual service utilisation rates. Four types of utilisation were modelled (i.e. overall, out-patient, in-patient, emergency clinic) using social indicators available from Statistics Canada census-tract data. Finally, a case-control study compared out-patients from a deprived and an affluent catchment area, matched case by case for primary diagnosis, age, sex and residential status (n = 52). RESULTS: Modelling proved highly predictive of utilisation, the overall-use model accounting for 73% of the variance. The case-control study indicated a higher rate of Axis II traits, substance abuse and needs for social care in the deprived catchment area. CONCLUSIONS: Resource allocation based on the social indicators modelling method was more consistent with sensible distribution of human resources. None of the methods, however, appear to reflect adequately the severity of caseloads evidenced in the case-control study.

Adolescent↗
PubMed1995

The chemotactic response of blood neutrophils and monocytes to strains of Escherichia coli with different virulence characteristics.

Chemotactic responses of blood neutrophils and monocytes to media conditioned by eight strains of Escherichia coli with different virulence characteristics were measured in modified Boyden assay chambers to determine if these characteristics were associated with differences in leucocyte mobility. Responding neutrophils and monocytes were prepared on conventional density gradients, and in three instances, the chemotaxis of eosinophils isolated on metrizamide gradients was also studied. Media conditioned by enteroinvasive and nonenteroinvasive E. coli strains were tested as chemo-attractants and compared to the formylated peptide standard attractant. Chemotactic activity of neutrophils was greater than that of monocytes and eosinophils, and migration by all populations was significantly greater to conditioned media than to the control medium. Chemotactic responses to media conditioned by non-enteroinvasive E. coli and strains lacking virulence factors was greater than to media conditioned by plasmid- and Sereny-positive enteroinvasive organisms. The results suggest that virulence factors of E. coli that determine invasiveness did not augment the chemotactic responses of the leucocyte populations tested in vitro, and give no support to the hypothesis that they induce mucosal inflammation by directly increasing chemotaxis in vivo.

Chemotaxis, Leukocyte↗
PubMed1995

Raf-1 N-terminal sequences necessary for Ras-Raf interaction and signal transduction.

Raf-1 is a serine/threonine protein kinase that transduces signals from cell surface receptors to the nucleus. Interaction of Ras with a regulatory domain in the N-terminal half of Raf-1 is postulated to regulate Raf-1 protein kinase and signaling activities. To better understand molecular interactions of Ras with Raf-1 and regulation of the Raf-1 kinase, a panel of Raf-1 N-terminal mutants expressed in the baculovirus-insect cell system was used for mapping the precise region necessary for Ras interaction in the context of full-length, functional Raf-1 kinase. An 80-amino-acid sequence in Raf-1 between positions 53 and 132 was found to confer the ability to bind Ras protein in vitro and in infected insect cells. Deletion of residues 53 to 132 abolished Raf-1 kinase activation by Ras in insect cells, indicating that activation of the Raf-1 kinase by Ras requires the capacity to physically interact with Ras. By contrast, deletion of this Ras-binding site did not diminish activation of Raf-1 kinase by Src, implying that Src and Ras can activate Raf-1 through independent mechanisms. Significantly, Raf-1 mutants lacking the entire zinc finger motif or containing substitutions of two critical cysteine residues in the zinc finger retained the ability to bind Ras and to be activated by this interaction. Consistent with results obtained in the baculovirus-insect cell system, deletion of residues 53 to 132 but not mutations in the zinc finger motif abrogated the ability of kinase-inactive, dominant negative Raf-1 to block Ras-mediated signaling in Xenopus oocytes. Together, these results provide evidence that the direct physical interaction of Ras with Raf-1 amino acids 53 to 132 is required for activation of the Raf-1 kinase and signaling activities by Ras but not by Src. Furthermore, the adjacent zinc finger motif in Raf-1 is not essential either for interaction with Ras or for activation of the Raf-1 kinase.

Animals↗
PubMed1995

Monocyte chemoattractant activity associated with human colon mucosal cells.

Mucosal epithelial cell preparations from 18 disease-free segments of human colon resections and 7 cell lines were examined for chemoattractant properties. Mucosal cells were dissociated from lamina propria by sequential incubations in ethylenediaminetetraacetic acid, harvested at 1.5 x 10(6) cells/ml, and lysed. Lysates were tested for chemoattractant activity for monocytes and neutrophils. Chemoattractant preparations were further purified by gel filtration chromatography, and amino acid analysis was performed on selected chemoattractant fractions. Mucosa from normal bowel exhibited significant chemoattractant properties for monocytes, up to 15 times greater than for neutrophils. Checkerboard analysis indicated chemotaxis rather than chemokinesis. Neither cell culture nor lamina propria cell lysates exhibited statistically significant chemoattraction, although activity was evident in certain preparations of isolated cell cultures. Chromatography of human mucosal chemoattractant preparations consistently gave peaks of activity in the 2000 dalton range. These yielded consistent amino acid profiles, with aspartic acid, glutamic acid, glycine, alanine, and lysine being dominant in all preparations. This peptide is apparently different from other known chemotactic agents and could play a role in recruitment of mononuclear phagocytes to the mucosa of the human colon.

Amino Acids↗
PubMed1994

Nerve growth factor derived from terminals selectively increases the ratio of p75 to trkA NGF receptors on mature sympathetic neurons.

Exposure of neuronal terminals to target-derived NGF has been hypothesized to regulate cell body responses at a distance. To test this hypothesis and, more specifically, to determine whether NGF distally regulates the synthesis of its two characterized receptors, we developed the following paradigm. Sympathetic neurons of the superior cervical ganglion (SCG) that project either to the eye or to the ear were labeled, in adult animals, with the retrograde tracers Fast Blue and Fluoro-Gold, respectively. NGF was then injected daily into the anterior chamber of one eye, exposing the terminals of the ipsilateral eye neurons to increased NGF. To control for systemic and/or localized injury effects, cytochrome C or PBS were injected into the contralateral eye of the same animals. In situ hybridization and image analysis were then used to determine neuronal levels of p75 NGF receptor, trkA, and T alpha 1 alpha-tubulin mRNAs, with the latter providing a correlative measure of neuronal sprouting. Morphological measurements revealed that exogenous, terminally-derived NGF increased the mean cross-sectional area of eye neurons by 37%. Grain counts for p75 NGF receptor mRNA increased from 2- to 6-fold in the NGF-treated neurons, and grain densities, which accounted for neuronal hypertrophy, also increased significantly. In contrast, grain counts for trkA mRNA were not significantly increased by this treatment, while T alpha 1 alpha-tubulin mRNA levels increased only 1.5- to 2-fold. No increase in grain density was detected for either of these mRNAs. The NGF-induced increased in p75 NGF receptor mRNA levels was accompanied by terminal sprouting and by an increase in the density of p75 NGF receptors on terminal neurites, as indicated by IgG-192 immunostaining of the NGF-treated iris. These data therefore suggest that, in addition to promoting local sprouting, increased target-derived NGF increases the levels of p75 NGF receptor relative to trkA on terminal neurites, by differentially regulating receptor synthesis. Such a direct regulatory feedback loop may well play an integral role in precisely modulating neuronal responses as a function of the amount of available trophic support and/or target tissue.

Animals↗
PubMed1993

The influence of occlusion time on measuring respiratory resistance and compliance in infants with bronchiolitis.

The passive, single-breath, flow-volume technique is a simple method for measuring the resistance (Rrs) and the compliance (Crs) of the respiratory system in infants. So far, the potential influence of end inspiratory occlusion time on these measurements has not been investigated. We measured Rrs and Crs in 36 infants and toddlers with bronchiolitis; in each child, a spectrum of nine fixed occlusion times, ranging from 90 to 600 ms, was applied in random sequence. Increasing the duration of occlusions from 90 to 275 ms resulted in marked stepwise changes of measured Rrs and Crs; occlusions longer than 275 ms, however, produced highly reproducible measurements, as expressed 1) by minimal absolute differences between measured values at subsequent occlusion times and 2) by minimal percentage changes of measured values from one occlusion time to the next. There was no influence of age on the results; reproducible measurements were made in children as old as 1.5 y. This suggests that, in infants with bronchiolitis, 1) occlusions between 300 and 450 ms might be ideal for obtaining reliable measurements, and 2) the age range for applying this method can be extended into the 2nd y of life.

Airway Resistance↗
PubMed1991

140-MDa plasmids of Escherichia coli and Shigella flexneri 5 do not influence phagocytosis.

Enteroinvasive Escherichia coli (EIEC) and Shigella flexneri possessing a 140-megadalton (MDa) plasmid are capable of invading intestinal epithelial cells and causing dysentery. To determine if this plasmid affected phagocytosis of the organisms by leukocytes, we studied the in vitro phagocytosis of isogenic pairs of EIEC and S. flexneri 5 which differed only in the presence or absence of the 140-MDa plasmid. In addition five EIEC strains containing 140-MDa plasmids as well as one non-enteroinvasive E. coli strain possessing a 120-MDa plasmid were studied. The 140-MDa plasmid did not affect phagocytosis of these bacteria by normal human blood neutrophils or monocytes.

Escherichia coli↗
PubMed1990

An historical perspective on crew rescue and the role of the Association of Space Explorers.

The Association of Space Explorers (ASE) has actively encouraged the development of an international space rescue capability. Safe operations in space preclude loss of life and the associated suspension of flight operations. Spaceflight has well definable risks that history demonstrates are real. While none of those killed thus far in spaceflight-related accidents could have been saved by an international rescue capability, several non-fatal incidents indicate that a need exists. Space treaties include the principles of rescue on Earth and in space. For nearly 30 years, technical papers have addressed rescue principles, hardware concepts, operations and planning, and international cooperation. However, only the Apollo-Soyuz flight of 1975 represents any movement toward establishing an international rescue capability. Recently, prompted by the U.S. Congress, renewed interest in international rescue studies, as well as Space Station Freedom options, is apparent. International meetings on space safety and rescue have been conducted or are planned for the immediate future. The difficulties of launch readiness, limitations imposed by orbital mechanics, and practical implications of international cooperation have been, and are being addressed. Responsiveness, compatibility, and mutual support are key ingredients to any international rescue plan. The ASE, representing astronauts and cosmonauts from 17 nations, strongly urges the continuation of studies and discussions among the spacefaring nations.

Astronauts↗
PubMed1986

A Drosophila melanogaster mutant resistant to a chemical analog of juvenile hormone.

Methoprene, a chemical analog of juvenile hormone, is toxic when applied to late third-instar larvae of Drosophila melanogaster. Using an ethyl methane sulfonate mutagenesis screen, we have selected two noncomplementing mutants, one of which is nearly 100 times more resistant than wild-type to either methoprene or juvenile hormone III topically applied or incorporated into the diet. The mutation, named methoprene-tolerant (Met), also confers resistance to methoprene-induced pseudotumor formation in larvae as well as to juvenile hormone III- or methoprene-induced vitellogenic oocyte development in adult females. Met adults show little or no cross-resistance to four other insecticides. The mutation was mapped by recombination to a location 35.4 on the X-chromosome and uncovered by chromosomes deficient for the region 10C2-10D4. Complementation was observed between Met and a lethal allele of the RNA polymerase II locus, which is also found in this region. Since the Met mutation also confers resistance to methoprene-induced abnormalities in adult cuticle formation, the autonomy of Met expression could be evaluated in flies mosiac for this mutation. Autonomous expression of Met was found both in abdominal cuticle as well as in external male genitalia. The characteristics of Met are consistent with those expected of a mutant having altered juvenile hormone reception in target tissue.

Age Factors↗