PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “SPACE MAINTENANCE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMedDate not supplied

Ridge augmentation with guided bone regeneration and GTAM case illustrations.

The principle of Guided Bone Regeneration (GBR) can be used for Ridge Augmentation. These case illustrations describe the technique using Autogenous Cortico-Cancellous Bone Grafts and stabilization with Miniscrews and placement of a GTAM Barrier Membrane. Nyman et al (1990) published the first report of enlargement of a reduced alveolar ridge. Becker & Becker, Jovanovic, Buser et al have documented successful regeneration of such ridges. A study by Lang et al established that: 1. An undisturbed healing period of at least six months is required for optimal bone regeneration. 2. Smaller defects (less than 70 mm.3) regenerate almost completely. 3. Larger defects (greater than 90 mm.3) regenerate 90-93 percent and bone grafts may enhance success in larger defects. 4. Premature membrane removal will result in incomplete regeneration. Buser et al have described the technique of GBR in detail. They found the creation and maintenance of a secluded space is essential for successful outcome with GBR procedures. This space allows for the in growth of osteogenic cells so that bone regeneration is undisturbed by competing non-osteogenic soft tissue cells. Space-making defects such as extraction sockets are simple to treat, but localized ridge augmentation may be difficult because the membrane is not supported by bony walls. E-PTFE membranes have been reinforced with titanium struts and mini screws have been developed as a way of dealing with membrane collapse. Buser et al began to utilize autogenous bone grafts to support the membrane and to act as an osseoinductive scaffold for bone regeneration. They utilized a cortico-cancellous block graft in the centre of the augmentative area with smaller chips to fill in the periphery. The cortical portion of the graft re-establishes the buccal cortex and the cancellous portion is placed against the host bone. The host bone is perforated to open the marrow spaces. Placement of membrane protects the bone graft (up to 50 percent of grafted bone is lost through resorption in augmentation procedures where membrane is not used).

Alveolar Ridge Augmentation↗
PubMed1975

Alleopathy and spatial competition among coral reef invertebrates.

Species of ectoprocts and solitary encrusting animals were subjected in aquaria to homogenates of 11 sympatric species of sponges and colonial ascidians. Five of the nine sponge species and one of the two ascidian species exhibited species-specific allelochemical effects. Evidence suggests that alleochemical provide a wide-spread, specific, and complex mechanism for interference competition for space among natural populations of coral reef organisms. The existence of such species-specific mechanisms may provide a basis for maintenance of diversity in space-limited systems in the absence of high levels of predation and physical disturbance.

Journal Article↗
PubMed1986

The structure and function of the outpatient endoscopy unit.

The authors present an analysis of the requirements for space, equipment, and personnel for an outpatient unit. These studies were derived from personnel and procedure time studies, evaluation of equipment and maintenance costs, and utilization of space studies and should be applicable to any outpatient endoscopy unit performing more than 1000 procedures per year.

Ambulatory Care↗
PubMed1994

Plasticity in the superior collicular auditory space map of adult guinea-pigs.

In the guinea-pig the development and maintenance of the superior collicular (SC) auditory space map requires both auditory and visual experience. This paper reports the results of experiments in which adult animals (of different ages) were dark-reared for 4 weeks to define the extent of the period of susceptibility to visual deprivation of the SC auditory map. Dark-rearing for 4 weeks from 100, 150 or 200 days after birth caused degradation of spatial tuning and topography of multi-unit auditory responses in the SC. In contrast, animals reared in the dark from 250 days after birth showed spatially tuned auditory responses similar to those seen in normal animals. These data suggest that the SC auditory space map in the adult guinea-pig remains susceptible to visual deprivation up to 200 days after birth.

Aging↗
PubMed2000

Structural macromolecules and supramolecular organisation of the vitreous gel.

The vitreous gel is a transparent extracellular matrix that fills the cavity behind the lens of the eye and is surrounded by and attached to the retina. This gel liquefies during ageing and in 25-30% of the oppulation the residual gel structure eventually collapses away from the posterior retina in a process called posterior retina in a process called posterior vitreous detachment. This process plays a pivotal role in a number of common blinding conditions including rhegmatogenous retinal detachment, proliferative diabetic retinopathy and macular hole formation. In order to understand the molecular events underlying vitreous liquefaction and posterior vitreous detachment and to develop new therapies it is important to understand the molecular basis of normal vitreous gel structure and how this is altered during ageing. It has previously been established that a dilute dispersion of thin (heterotypic) collagen fibrils is essential to the gel structure and that age-related vitreous liquefaction is intimately related to a process whereby these collagen fibrils aggregate. Collagen fibrils have a natural tendency to aggregate so a key question that has to be addressed is: what normally maintains the spacing of the collagen fibrils? In mammalian vitreous a network of hyaluronan normally fills the spaces between these collagen fibrils. This hyaluronan network can be removed without destroying the gel structure, so the hyaluronan is not essential for maintaining the spacing of the collagen fibrils although it probably does increase the mechanical resilience of the gel. The thin heterotypic collagen fibrils have a coating of non-covalently bound macromolecules which, along with the surface features of the collagen fibrils themselves, probably play a fundamental role in maintaining gel stability. They are likely to both maintain the short-range spacing of vitreous collagen fibrils and to link the fibrils together to form a contiguous network. A collagen fibril-associated macromolecule that may contribute to the maintenance of short-range spacing is opticin, a newly discovered extracellular matrix leucine-rich repeat protein. In addition, surface features of the collagen fibrils such as the chondroitin sulphate glycosaminoglycan chains of type IX collagen proteoglycan may also play an important role in maintaining fibril spacing. Furthering our knowledge of these and other components related to the surface of the heterotypic collagen fibrils will allow us to make important strides in understanding the macromolecular organisation of this unique and fascinating tissue. In addition, it will open up new therapeutic opportunities as it will allow the development of therapeutic reagents that can be used to modulate vitreous gel structure and thus treat a number of common, potentially blinding, ocular conditions.

Aging↗
PubMed1962

Laboratory breeding and testing of Australorbis glabratus for molluscicidal screening.

The authors describe a technique for laboratory breeding of Australorbis glabratus, the intermediate host of Schistosoma mansoni in South America. This technique is suitable for obtaining large numbers of snails in a small space with the minimum of maintenance time and under carefully controlled conditions.Techniques are also outlined for testing molluscicides against eggs and young snails as well as against adults. It is considered that, in view of the saving in breeding time and space effected, testing against young snails has several advantages for primary screening. With no compounds tested have anomalous results been obtained.Finally, the authors report on the results obtained with a new class of molluscicidal compounds-the organo-tins-which cause snail mortality in concentrations as low as those of any of the other molluscicides tested.

Animals↗
PubMed1991

Microgravity testing a surgical isolation containment system for space station use.

Anticipated hazards for crewmembers in future long term space flights may result in a variety of injuries including trauma and burns. Management of these injuries will require special techniques because of the lack of gravity, limitations of space and environmental restrictions. A small surgical isolation containment system was developed and tested in microgravity. The chamber provided both protection of the injury and of the cabin environment and is felt to be the most effective means of trauma and burn care in future Health Maintenance Facilities planned for prolonged space exposure.

Operating Rooms↗
PubMed1985

Changes in body compartments on different types of haemodialysis.

Changes in plasma volume (PV), extracellular volume (ECV) and intracellular volume (ICV) were studied in seven patients on conventional haemodialysis (HD) and in six patients on stable hypertonic HD. Weight loss and ultrafiltration were similar in both groups. Before HD the spaces of 125RISA (PV), 35SO4Na2 (ECV) and 3H2) (total body water, TBW) were simultaneously determined ICV = TBW - ECV. At the end of HD the space of 35SO4Na2 was again tested. PV and ECV diminished more on conventional HD than on hypertonic HD, whereas ICV increased on conventional HD and decreased on hypertonic HD. The handling of plasma osmolality during HD is an effective method for modifying transcompartmental body fluid shifts in HD by distributing weight loss between intracellular and extracellular spaces allowing for a better maintenance of plasma volume.

Adult↗
PubMed1994

Adaptive plasticity of the auditory space map in the optic tectum of adult and baby barn owls in response to external ear modification.

1. This study demonstrates the influence of experience on the establishment and maintenance of the auditory map of space in the optic tectum of the barn owl. Auditory experience was altered either by preventing the structures of the external ears (the facial ruff and preaural flaps) from appearing in baby barn owls (baby ruff-cut owls) or by removing these structures in adults (adult ruff-cut owls). These structures shape the binaural cues used for localizing sounds in both the horizontal and vertical dimensions. 2. The acoustic effects of removing the external ear structures were measured using probe tube microphones placed in the ear canals. In both baby and adult ruff-cut owls, the spatial pattern of binaural localization cues was dramatically different from normal: interaural level difference (ILD) changed with azimuth instead of with elevation, the rate of change of ILD across space was decreased relative to normal, and the rate of change of interaural time difference (ITD) across frontal space was increased relative to normal. 3. The neurophysiological representations of ITD and ILD in the optic tectum were measured before and > or = 3 mo after ruff removal in adults and beginning at 4.5 months of age in baby ruff-cut owls. Multiunit tuning to ITD and to ILD was measured using dichotic stimulation in ketamine-anesthetized owls. The tectal maps of ITD and ILD were reconstructed using visual receptive field location as a marker for recording site location in the optic tectum. 4. Adjustment of the tectal map of ITD to the altered spatial pattern of acoustic ITD was essentially complete in adults as well as in baby ruff-cut owls. This adjustment changed the magnification of ITD across the tectum, with resultant changes in ITD tuning at individual tectal sites of up to approximately 25 microseconds (approximately 5% of the physiological range) relative to normal values. 5. Adaptation of the tectal ILD map to the ruff-cut spatial pattern of acoustic ILD was substantial but clearly incomplete in both adult and baby ruff-cut owls. Although changes of up to approximately 15 dB (approximately 47% of the physiological range) relative to normal tuning were observed at certain tectal sites, the topography of the ILD map was always intermediate between normal and that predicted by the ruff-cut spatial pattern of acoustic ILD.(ABSTRACT TRUNCATED AT 400 WORDS)

Acoustic Stimulation↗
PubMed2002

Maintenance of ATP favours apoptosis over necrosis triggered by benzamide riboside.

A new synthetic drug, benzamide riboside (BR) exhibited strong oncolytic activity against leukemic cells in the 5-10 microM range. Higher BR-concentrations (20 microM) predominantly induced necrosis which correlated with DNA strand breaks and subsequent depletion of ATP- and dATP levels. Replenishment of the ATP pool by addition of adenosine prevented necrosis and favoured apoptosis. This effect was not a pecularity of BR-treatment, but was reproduced with high concentrations of all trans-retinoic acid (120 microM) and cyanide (20 mM). Glucose was also capable to suppress necrosis and to favour apoptosis of HL-60 cells, which had been treated with necrotic doses of BR and cyanide. Apoptosis eliminates unwanted cells without affecting the microenvironment, whereas necrosis causes severe inflammation of surrounding tissues due to spillage of cell fluids into the peri-cellular space. Thus, the monitoring and maintenance of cellular energy pools during therapeutic drug treatment may help to minimize nonspecific side effects and to improve attempted drug effects.

Adenosine↗
PubMed2004

Ontogenesis of mammals and gravity.

The results of the experiments with Wistar rats in microgravity and 2G hypergravity are summarized. Their analysis allows to conclude that adaptive potentials of adult animals in space flights lasting up to 1/50 of their life span are enough for maintenance of adequate reactions to acute and chronic stressors in the postflight period, rapid elimination of space-induced metabolic and structural alterations on return to Earth, maintenance of normal reproductive function after space flight. In embryological experiments it was demonstrated that during space flight it is possible not only to maintain physiological functions of an adult organism, but to form functions of a developing fetus. The animals that spent the portion of their prenatal development in space flight were capable to go through the entire cycle of postnatal development, up to sexual maturity and reproduction. In ground based centrifuge experiments with 2G it was demonstrated the possibility of realizing, under hypergravity, of all the main stages of prenatal and early postnatal development of rats: fertilization, embryon implantation, fetal development, birth and lactation of progeny. Exposure of rats to microgravity did not reduce their life span post flight. Alterations in biological age of animals were small.

Adaptation, Physiological↗
PubMed1977

Optic nerve decompression. A clinical pathologic study.

Decompression of the perioptic meninges for intractable chronic papilledema was done in a patient with a right parietal temporal glioblastoma multiforme. The patient died 39 days postoperatively. Histologic study of the optic nerves indicated fistulas in the dura compatible with cerebrospinal fluid (CSF) egress and maintenance of a normal subarachnoid space around the nerve. Two additional patients with unilateral optic nerve decompression producing bilateral resolution of papilledema were studied. We contend that egress of CSF was the principle mode of action in these three cases. How long the dural fistula remains patent is unknown. Reports in the literature show considerable variation in the effects of optic nerve decompression. Anatomic variation of the intracanalicular subarachnoid space together with differences in underlying pathologic condition, surgical technique, and patient response may explain discrepancies among the results reported.

Adolescent↗
PubMed2003

Regulatory mechanisms of periodontal regeneration.

The periodontal ligament, located between the cementum and the alveolar bone, has a width ranging from 0.15 to 0.38 mm. Regeneration and homeostasis of the periodontal ligament are highly significant functions in relation to periodontal therapy, tooth transplantation or replantation, and orthodontic tooth movement. The purpose of this review is to discuss the regulatory mechanisms of regenerative and homeostatic functions in the periodontal ligament based on currently published studies and also on our own experimental data. We consider the capability of the ligament tissue to promote or to suppress calcification in connection with bone and cementum formation and the maintenance of the periodontal ligament space. Also discussed are the involvement of the periodontal ligament tissue in the regenerative ability, cell proliferation, growth and differentiation factors, extracellular matrix proteins, homeostatic phenomena, function of Malassez epithelial rests, tooth movement, or occlusal loading. Regulatory mechanisms for regeneration and homeostasis of the periodontal ligament are hypothetically proposed.

Animals↗
PubMed1994

Effect of active transport on distribution and concentration gradients of [3H]benzylpenicillin in the cerebrospinal fluid.

After application of [3H]benzylpenicillin ([3H]BP) in lateral brain ventricle in dogs, the distribution of [3H]BP to contralateral ventricle and cisterna magna was much higher when its active transport from cerebrospinal fluid (CSF) was blocked by probenecid than under control conditions. Analysis of [3H]BP concentrations in both lateral ventricles and cisterna magna over time indicates that active transport restricts distribution of substances along CSF spaces and contributes to the maintenance of their concentration gradients between CSF compartments. This suggests that biochemical changes in a part of the brain and the adjacent CSF compartment may not be reflected into remote compartments of CSF such as lumbar CSF if substances in question are removed from CSF by active transport.

Animals↗
PubMed2004

Mechanical ventilation in orbit: emphasis on closed-loop ventilation.

As part of a Crew Health Care Maintenance System onboard the International Space Station, the National Aeronautics and Space Administration has included a Respiratory Support Pack (RSP) to resuscitate or sustain a crew member with an acute impairment in pulmonary function. This article provides a critical appraisal of the RSP and of current strategies for mechanical ventilation in space. Various closed-loop ventilation strategies are reviewed,and their appropriateness for respiratory support in space is explored. Recommendations are made for enhancing and upgrading the current RSP to provide an injured crew member with the best possible chance of survival.

Aerospace Medicine↗
PubMed2002

Tracheotomy versus endotracheal intubation for airway management in deep neck space infections.

PURPOSE: The aim of the present study was to compare costs and outcomes for patients with deep neck infections who were treated with either tracheotomy or endotracheal intubation. MATERIALS AND METHODS: The charts of 85 patients with deep neck space infections were retrospectively studied. Requirements for inclusion in the study were incision and drainage in the operating room, involvement of more than 1 deep anatomic space, impending airway compromise, and maintenance of a postoperative artificial airway. The 85 patients were divided into 2 groups based on the type of airway used for treatment. Group 1 (n = 34) included patients who received a tracheotomy, and group 2 (n = 51) included patients whose airways were maintained with endotracheal intubation until the swelling had resolved sufficiently for extubation. RESULTS: Patients in group 1 had a shorter overall hospital stay (4.8 vs 5.9 days, NS) and spent less time in the intensive care unit (1.1 vs 3.1 days, P <.05). The overall incidence of complications was 6% for group 1 and 10% for group 2. The rate of complications secondary to loss of airway was 3% for group 1 and 6% for group 2. Average costs associated with intensive care resources were 5 times greater and overall hospital stay costs were 60% greater for group 2. CONCLUSIONS: Although both methods of airway control are useful and have a unique set of complications, the use of tracheotomy allowed earlier movement to a noncritical care unit and was associated with fewer intensive care costs and less overall cost of hospitalization. Tracheotomy may therefore provide better utilization of critical care resources in this group of patients.

Adult↗
PubMed1997

Minimally invasive videoscopic parathyroidectomy: a feasibility study in dogs and humans.

BACKGROUND: With increasing experience using preoperative sestamibi nuclear scanning, several reports have shown that selective unilateral neck exploration is sufficient in most patients with primary hyperparathyroidism. The current study was undertaken to determine the feasibility of videoscopic parathyroidectomy as a means to decrease scar size while allowing adequate exposure for the identification of normal parathyroid glands and removal of those glands that are enlarged. STUDY DESIGN: Eight mongrel dogs underwent removal of all parathyroid glands and both lobes of the thyroid using videoscopic techniques. Once the technical aspects of the operation were established, four patients with primary hyperparathyroidism underwent sestamibi-directed unilateral videoscopic neck exploration with attempted parathyroid removal. RESULTS: All thyroid and parathyroid tissues were removed from each dog without complications. Maintenance of an adequate working space proved to be the major difficulty that necessitated placement of a small mechanical retractor. This problem was even more severe in humans, which prevented the identification of one of four adenomas and three of four normal glands. CONCLUSIONS: Although videoscopic surgery is possible within the loose connective tissues of the canine neck, the inability to establish an adequate working space within the neck of humans and the location of parathyroid glands behind the thyroid precludes the use of this technique for patients with hyperparathyroidism.

Adenoma↗