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PubMed1998

Recycling isoelectric focusing and isotachophoresis.

Of all electrophoretic methods, isoelectric focusing offers the highest resolution and is best suited for preparative applications. Over the years, several instruments were developed for this purpose, all operating in free fluids, in the absence of gels or other supporting matrices. In such systems, the avoidance of gravity or electrically driven convections is essential. Successful stratagems for fluid control included rapid recycling or rotation, in combination with either fine porosity screens or narrow gaps between parallel plates. The most successful apparatus so far is the Rotofor, in which fluid is stabilized by combining horizontal rotation with fine porosity screen partitioning. Recycling isotachophoresis offers the potential of separating proteins at high concentration. A new concept of tangential electrophoresis is described. To optimize the use of these devices for protein separation, low molecular weight, biologically acceptable buffers of known composition are essential. The buffering system developed for this purpose comprises a series of binary buffers that cover the pH range in steps of 1 pH unit or less. The pH gradient can be custom-designed and is of remarkable stability in operation.

Buffers↗
PubMed1989

Insects as test systems for assessing the potential role of microgravity in biological development and evolution.

Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into account in the planning and evaluation of experiments designed to test the potential role of microgravity on biological developmental and evolution.

Animals↗
PubMed1977

A new type of cytocentrifuge, the valve-centrifuge.

A new type of cytocentrifuge has been developed in which the sedimentation process of the cells onto the slides is separated from the draining of the sedimentation fluid. This is realised by electrically controlled valves which can be closed and opened while the centrifuge is running. Sedimentation is carried out with closed valves, draining of adhering medium with open valves. The preparations, freed of adhering medium by the centrifugal force can be taken out and the cells can be fixed. Alternatively the valves can be closed again and fixative can be introduced through a central well, the cells still being under the influence of the centrifugal force. With subsequent draining of the fixative and introduction of washing and staining solutions through the central well, the whole process from sedimentation to staining can be carried out in the running centrifuge. The process seems well suited for complete automation. Using dilution series from a suspension of human buffy coat cells counted in a Buerker chamber, the cell counts in the centrifuge preparations showed virtually total recovery of cells, with no apparent selection or specific distribution of cell types. Draining of the sedimentation and fixative fluids at a slow rate was found to be vital for optimal recovery of cells. The morphology of different cell types sedimented on the slide was excellent. The flattening of nuclei thorugh gravity was studied by cytophotometry of Feulgen-stained leucocytes. The nuclear area of these cells was found to be approximately double that from cells in identically stained classical smears. With this type of valve-centrifuge a quantitative and unbiased recovery of uniformly spread and flattened cells on coverslips or slides may be obtained, thus making the procedure well suited to automated analysis based on cytophotometric principles and morphometric pattern recognition.

Animals↗
PubMed1994

[Pathological body sensations (sensopathies) in the structure of somatization disorders within the scope of minor psychiatry].

Pathological somatization sensations (sensopathies) in a random samples of 40 patients were lined according to their increasing gravity: paresthesias--psychalgias--hysteroalgias--senesthoalgias+ ++ --senesthopathies--senesthesias--tactile and visceral hallucinations. The more distant is sensopathy from the beginning of the line, the more limited are its syndrome characteristics and higher therapeutic tolerance. Nosological distribution also suits the line: neurotic reactions and neuroses stand first followed by psychogenic depressions, psychopathies, cyclothymias with hypochondriac conditions and schizophrenias in the end. Sensopathies, combinations and dynamics thereof are of importance for diagnosis, some of them may correspond to certain nosological entities. Chemotherapy of most tolerant sensopathies is detailed.

Adolescent↗
PubMed2006

Lessons learned from LNG safety research.

During the period from 1977 to 1989, the Lawrence Livermore National Laboratory (LLNL) conducted a liquefied gaseous fuels spill effects program under the sponsorship of the US Department of Energy, Department of Transportation, Gas Research Institute and others. The goal of this program was to develop and validate tools that could be used to predict the effects of a large liquefied gas spill through the execution of large scale field experiments and the development of computer models to make predictions for conditions under which tests could not be performed. Over the course of the program, three series of LNG spill experiments were performed to study cloud formation, dispersion, combustion and rapid phase transition (RPT) explosions. The purpose of this paper is to provide an overview of this program, the lessons learned from 12 years of research as well as some recommendations for the future. The general conclusion from this program is that cold, dense gas related phenomena can dominate the dispersion of a large volume, high release rate spill of LNG especially under low ambient wind speed and stable atmospheric conditions, and therefore, it is necessary to include a detailed and validated description of these phenomena in computer models to adequately predict the consequences of a release. Specific conclusions include: * LNG vapor clouds are lower and wider than trace gas clouds and tend to follow the downhill slope of terrain due to dampened vertical turbulence and gravity flow within the cloud. Under low wind speed, stable atmospheric conditions, a bifurcated, two lobed structure develops. * Navier-Stokes models provide the most complete description of LNG dispersion, while more highly parameterized Lagrangian models were found to be well suited to emergency response applications. * The measured heat flux from LNG vapor cloud burns exceeded levels necessary for third degree burns and were large enough to ignite most flammable materials. * RPTs are of two types, source generated and enrichment generated, and were observed to increase the burn area by a factor of two and to extend the downwind burn distance by 65%. Additional large scale experiments and model development are recommended.

Accidents↗
PubMed1998

[The influence of space loading suits on interhemispheric asymmetry of the brain in infantile spastic cerebral palsy].

The paper presents the study concerning influence of somatosensory stimulation (single wearing of either space loading costume "PENGUIN" or its modification--"ADELY" costume) on the individual profile of interhemispheral cerebral assymmetry (IPIHCA) in patients with spastic form of infantile cerebral paralysis (ICP). The computer stabilograph analyzed motor arms' asymmetry, sensory asymmetry of visual hemiareas, asymmetry of the position of centre of gravity. It is shown that peculiarities of the realization of the standing position either with visual control or without it both in healthy individuals and in patients depended on initial IPIHCA. Initial stability was higher in healthy individuals than in patients, besides in healthy persons it was higher in right-handers while in patients--in left-handers. There was possibility of changes of both IPIHCA and stability during keeping up vertical position even during single somatosensory stimulation. For elaboration of new criteria of the estimation of the efficiency of treatment in patients with CNS damages, including ICP, it is necessary to take into consideration different influence of somatosensory stimulation on IPIHC in right-handers and left-handers.

Adolescent↗
PubMed1998

[Skin gangrene of the external genitalia. Report of 44 cases].

STUDY AIM: The aim of this study is to report 44 cases of male external genitalia cutaneous gangrene which have been observed at the Principal Hospital of Dakar (Senegal) during a 4-year period. PATIENTS AND METHODS: The patients all belonged to a black and poor population (mean age: 60 years). Diabetes was present in 11% of the patients. In ten patients, no aetiology was found. The other 34 cases were secondary mainly to urogenital pathology (50%). In 50% of the cases, the lesions were localised on the external genitalia, in the other 50%, the lesions had spread to the hypogastrium and/or the perineum. Medical treatment included intensive care and triple antibiotic therapy, penicillin, gentamycin and metronidazole. A hyperbaric oxygen therapy was associated in 25% of the cases. The surgical treatment in the acute period included incising, debridement, paring, draining, urinary derivation (n = 36), and colostomy (n = 5). Thirteen patients had the benefit of sequential and prospective bacteriological tests. RESULTS: Spontaneous healing was obtained in 48% of the patients within 2 to 3 months. Secondary reconstructive surgery consisted mainly in cutaneous grafts. Global mortality rate was 34%, mortality rate was 30% in the secondary gangrenes, 40% in the primitive gangrenes. Mean hospitalisation duration was 6 weeks. Main sequelae were cheiloïd scars. CONCLUSIONS: The authors try to clarify the nosological imprecisions of this pathology by distinguishing between the secondary types and the primitive types corresponding to Fournier's gangrene, which still inspires many questions concerning its etio-pathogenesis. The surgical treatment must eradicate all necrosis by suited iterative procedures, associated with local care. Hyperbaric oxygen therapy was not efficient in this series. This pathology, although rare, needs to be better known, because only an early and efficient surgical and medical treatment will be able to decrease the exceptional gravity of the prognosis.

Adult↗
PubMed1981

Separation of haemopoietic cells for biochemical investigation. Preparation of erythroid and myeloid cells from human and laboratory-animal bone marrow and the separation of erythroblasts according to their state of maturation.

The separation of haemopoietic bone-marrow cells by centrifugation through discontinuous density gradients of Percoll is described. This method was used to prepare fractions enriched in erythroblasts, myeloid blast cells or reticulocytes from bone marrow of anaemic and non-anaemic rabbits, from the marrow of other anaemic laboratory animals and from human samples. It is a simple, rapid, reproducible and inexpensive technique that can be readily adapted to suit individual requirements. Secondly, a convenient method is presented for the separation of large quantities of bone-marrow cells into fractions enriched in erythroblasts at different stages of maturation, by velocity sedimentation through a linear gradient of 1-2% sucrose at unit gravity. In vitro, erythroblasts adhere together strongly via a mechanism almost certainly involving a beta-galactoside-specific surface lectin termed erythroid developmental agglutinin. Since the efficiency of cell-separation techniques depends heavily on the maintenance of a single cell suspension in which each unit can move independently, the presence of an adhesive molecule at the cell surface is of considerable significance. The effect of washing the marrow with a lactose-containing medium, which has been shown to remove the agglutinin, was therefore investigated in relation to both methods. The separation on Percoll gradients is considerably enhanced by this treatment. In addition, the unit-gravity sedimentation gradient can be loaded with 5-10 times more cells after lactose extraction in comparison with intact marrow. Although enrichment is less, a useful fractionation according to maturation is still obtained.

Anemia↗
PubMed1985

Evaluation of a pump in enteral tube feeding in terms of patient and staff acceptance: a retrospective study.

A retrospective study of 39 patients fed via an enteral tube was carried out using data from patients records. An enteral feeding pump was available for all patients. Its use was evaluated in terms of patient and staff acceptance of the technique. The pump was shown to be particularly suited to patients following gastrointestinal surgery and trauma in whom tube feeding might be expected to produce gastrointestinal side-effects. Patients with lower nutritional requirements and without gastrointestinal trauma do not require such accurate flow control and for non-clinical reasons an alternative technique such as gravity drip feed or bolus feeding may be preferred. The conclusions which can be drawn from a study of this nature are limited but it does draw attention to the importance of considering, in addition to the expected clinical tolerance, the acceptance by patient and staff of the technique for the individual.

Attitude↗
PubMedDate not supplied

A gyroscope deviometer for measurement of strabismus.

We describe a hand-held gyroscope deviometer that an examiner can use to measure strabismic deviations without prisms. The deviometer is ideally suited for use with small children who will not allow prisms to be held near their eyes, and adults with poor fixation in one eye. The device consists of a fixation light attached to a gimbal-mounted single-axis gyroscope. The gyroscope provides the necessary reference for horizontal deviations. Gravity provides the reference for vertical deviations. As the patient observes his or her reflection with the fixing eye in a plane mirror at the end of the room, the examiner positions the corneal light reflex in the pupil of the deviating eye and presses a rocker switch to the "reset" position, zeroing the deviometer. The examiner then aims the deviometer fixation light at a reflection of itself in a plane mirror located on the wall behind the subject and presses the rocker switch to the "read" position. Horizontal and vertical deviations are displayed to the nearest degree. The accuracy of the device is dependent upon the examiner's ability to position the corneal light reflex correctly in the pupil of the deviating eye.

Blinking↗
PubMed1986

A simple method of granulocyte enrichment of crude white cell suspensions labelled with 111In.

A simple method of granulocyte enrichment of a 111In-labelled mixed white cell suspension is described. The method rests on preferential sedimentation by gravity of the granulocytes during labelling. In the 50 studies performed, the granulocytes constituted on average 90% of the 111In-labelled white cells injected for abscess detection. The modest degree of artefactual granulocyte pooling in the lungs and the results of the scintigraphic studies suggest that the method described is well-suited for scintigraphic localization of infectious and inflammatory processes.

Abscess↗
PubMed2000

Vertical and horizontal posture during suited immersion: similarity and differences according to some body functions.

The role of axial body orientation was weighed during acute adaptation to suit immersion (SI) in 3 hr vertical (SIv, n=4) exposure series, and 3 d experiments in which six volunteers participated in both SIv and SIh. Various types of SI recruited different hormonal mechanisms to induce similar reactions of the water-electrolyte metabolism (WEM). Changes in the body position relative to the gravity vector modified equally strength and dynamics of the WEM regulation. The experimental data suggest that osmo- and volume-regulation reactions to SIv shown the response to the actual volumetric stimulus against the "distributed" weight-bearing reaction. They are less vigorous as compared to SIh and do not reach maximum within 3 hrs. Physiological reactions to SIh were marked by greater effects of ADH on the kidney when compared with dry immersion, and an additional stimulation of aldosterone secretion by the sympathetic nervous system and/or ACTH. SIh caused rapid and more heavy symptoms of motion sickness that correlated with body mass reduction, negative water balance, degradation of tolerance of classic physical tests executed after SI. Three-days SIv, as opposed to SIh, resulted in more profound hypervolemia in the upper body of the test-subjects.

Adaptation, Physiological↗
PubMedDate not supplied

[Vesico-renal reflux in adults (author's transl)].

This article is based on an analysis of 88 cases of vesico-renal reflux, 43 primary and 45 secundary ones. The author consider successively the clinical, bacteriological, radiological and endoscopical facts and their relations to the different types of reflux. They emphasize the frequency and the gravity of the primary reflux in adults and its probable connection with the genesis of the non-obstructive pyelonephrities and the unilateral renal atrophies. Its noxioness is primarily connected with the infection. The secundary reflux, however, even infected, is relatively well tolerated in adults. In case of primary vesico-renal reflux the therapeutical conduct has to be extremely well suited. A surgical correction should only be considered if the kidney has satisfactorily maintained its fonction and if the tonicity of the excreting ways is still good enough. In case of secundary reflux, the therapeutical conduct depends first of all on the etiology. In the group of primary reflux 11 patients derived benefit from ureteral reimplantation; whereas in the group of secundary reflux only 5 patients were submitted to an operation. The method applied was that of Paquin.

Adolescent↗
PubMed1986

A new tremor balance-transducer.

A new tremor-measuring device has been developed. It is constructed as a beam balance and measures principally in a vertical direction. Both arms of the beam contain a ceramic crystal; one of the arms has an extension that rests on the object to be measured. In this way, problems associated with mounting the transducer to the object are eliminated. The balance-transducer performs a well defined rotational movement in contrast to the frequently used transducers with a single sensor which are mounted to the object. The tremor movement of the limb and/or inadequate mounting causes unknown variation in the influence of the gravity component on the sensor; this can cause substantial errors. This tremor-transducer eliminates this problem. The static load of the balance-transducer on the object can be adjusted to less than 0.5 X 10(-3) kg(0.005 N). Even in the case of finger tremor, the balance-transducer does not influence the tremor phenomenon significantly. The principle of the balance-transducer is suited to measurements of postural, intention and limited action tremor of the finger, hand, forearm and jaw.

Biomechanical Phenomena↗
PubMed1993

Rationale for a hyperbaric treatment capability at a Lunar Station.

Missions to establish a permanent presence on the Moon will include a significant amount of extravehicular activity (EVA), which carries the risk of decompression sickness (DCS). Factors which will influence that risk include: cabin and space suit pressure environments, frequency of an activity level during EVA, and the possibility of a loss-of-pressure mishap. These factors were considered for Space Station Freedom (SSF), resulting in the decision to include a hyperbaric airlock capable of treating DCS. Using concepts from operational medicine, the need for such a capability is determined by its influence on mission risk. In comparison to SSF, a Lunar Station will have gravity, a higher EVA rate, physically more DCS provocative EVA, and little, if any, capacity for medical evacuation. Therefore, unless Lunar mission planners can provide pressure environments that offer near zero risk of DCS for nominal operations, a hyperbaric treatment capability should be included.

Aerospace Medicine↗
PubMed1999

The sitting position in neurosurgery: a critical appraisal.

The potential for serious complications after venous air embolism and successful malpractice liability claims are the principle reasons for the dramatic decline in the use of the sitting position in neurosurgical practice. Although there have been several studies substantiating the relative safety compared with the prone or park bench positions, its use will continue to decline as neurosurgeons abandon its application and trainees in neurosurgery are not exposed to its relative merits. How can individual surgeons continue to use this position? Will individual, difficult surgical access cases be denied the obvious technical advantages of the sitting position? Limited use of the sitting position should remain in the neurosurgeon's armamentarium. However, several caveats must be emphasized. Assessment of the relative risk-benefit, based on the individual patient's physical status and surgical implications for the particular intracranial pathology, is of paramount importance. The patient should be informed of the specific risks of venous air embolism, quadriparesis and peripheral nerve palsies. Appropriate charting of patient information provided and special consent issues are essential. An anaesthetic input into the decision to use the sitting position is a sine qua non. The presence of a patient foramen ovale is an absolute contraindication. Preoperative contrast echocardiography should be used as a screening technique to detect the population at risk of paradoxical air embolism caused by the presence of a patent foramen ovale. The technique involves i.v. injection of saline agitated with air and a Valsalva manoeuvre is applied and released. Use of this position necessitates supplementary monitoring to promptly detect and treat venous air embolism. Doppler ultrasonography is the most sensitive of the generally available monitors to detect intracardiac air. The use of a central venous catheter is recommended, with the tip positioned close to the superior vena cava junction with the right atrium, to aspirate intravascular gas. Measures to minimize hypotension associated with the sitting position include a slow, staged positioning over 5-10 min and use of the 'G suit' inflated with compressed air applied to the lower extremities and pelvis. Use of the sitting or upright position for patients undergoing posterior fossa and cervical spine surgery presents unique challenges for the anaesthetist. With appropriate patient selection and preparation, and using prudent intraoperative monitoring and anaesthetic techniques, selected patients should still benefit from the optimum access to mid-line lesions, improved cerebral venous decompression, lower intracranial pressure and enhanced gravity drainage of blood and CSF associated with the sitting position.

Anesthesia↗
PubMed2004

Sphere-filled organ model for virtual surgery system.

We have been developing a virtual surgery system that is capable of simulating surgical maneuvers on elastic organs. In order to perform such maneuvers, we have created a deformable organ model using a sphere-filled method instead of the finite element method. This model is suited for real-time simulation and quantitative deformation. Furthermore, we have equipped this model with a sense of touch and a sense of force by connecting it to a force feedback device. However, in the initial stage the model became problematic when faced with complicated incisions. Therefore, we modified this model by developing an algorithm for organ deformation that performs various, complicated incisions while taking into account the effect of gravity. As a result, the sphere-filled model allowed our system to respond to various incisions that deform the organ. Thus, various physical manipulations that involve pressing, pinching, or incising an organ's surface can be performed. Furthermore, the deformation of the internal organ structures and changes in organ vasculature can be observed via the internal spheres' behavior.

Animals↗
PubMed1976

A raft technique for chemotaxis: a versatile method suitable for clinical studies.

We describe a raft technique for the study of chemotaxis which possesses a number of advantages over the use of chambers. Membranes are laid on pads soaked in chemotactic agent and cells are contained in plastic cups, which are inverted on to the membrane. This method gives results which are similar to those obtained in conventional vessels. It would seem well suited to comparative measurements of chemotaxis in clinical series, for it avoids the use of special chambers, minimises the number of membranes and their handling and more than one cell suspension can be placed on a membrane. In addition, the method is experimentally versatile: simple manipulations allow work with cells adherent to other surfaces, studies of the effect of substituting a new agent or of reversing the gradient during an experiment, migration against gravity, and of the effect of non-adherent cells on migrating cells.

Animals↗