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At least 667 records · Page 37Linked to original sources
PubMed2000

Freely movable armrest for microneurosurgery: technical note.

OBJECTIVE: To introduce an armrest that can move freely and can promptly be fixed at any desired position during surgery. METHODS: We developed a surgical armrest system that incorporates a mechanical arm, equipped with a ball joint, which can be fixed by frictional resistance. The mechanical arm moves freely as compressed air is applied. As the button switch below the armrest is pressed while the armrest is being held (grip switch), the mechanical arm can move freely to the desired position. The mechanical arm is locked in position as soon as the button is released. RESULTS: The stability of the surgeon's hands was markedly increased, and fatigue was markedly decreased, during surgery conducted using this armrest system. The system was used for 60 operations in 6 months without any problems. CONCLUSION: The freely movable armrest is useful for neurosurgical procedures that require agility and fine movements of the hand.

Arm↗
PubMed2001

Diving: what to tell the patient with asthma and why?

Until a decade ago, divers with asthma were uniformly barred from diving with compressed air. This prohibition was based more on theoretical concerns for barotrauma than on actual data. Follow-up studies, although retrospective, do not support a ban on recreational or commercial diving for divers with stable asthma. These studies have noted that, despite the prohibition on diving, many divers with asthma have logged multiple dives without negative consequences. When those who have suffered diving-related barotrauma have undergone physiologic testing, measurements of small airways dysfunction (maximal mid-expiratory flow rates) have been lower than measurements for comparable divers who have never suffered diving accidents. Follow-up studies with long-term commercial divers have shown that a small percentage of individuals who have sufferred diving-related barotrauma also develop abnormal maximal mid-expiratory flow rates and even some airway hyperreactivity. These latter findings correlate with the changes that occur in chronic asthmatic patients, especially those who are not well treated. The decision as to whether an asthmatic patient should be allowed to dive rests on the individual's physiologic function, maturity, and insight into the consequences of poorly managed airway inflammation and bronchospasm.

Asthma↗
PubMed1999

Thermotolerance of leaf discs from four isoprene-emitting species is not enhanced by exposure to exogenous isoprene

The effects of exogenously supplied isoprene on chlorophyll fluorescence characteristics were examined in leaf discs of four isoprene-emitting plant species, kudzu (Pueraria lobata [Willd.] Ohwi.), velvet bean (Mucuna sp.), quaking aspen (Populus tremuloides Michx.), and pussy willow (Salix discolor Muhl). Isoprene, supplied to the leaves at either 18 &mgr;L L-1 in compressed air or 21 &mgr;L L-1 in N2, had no effect on the temperature at which minimal fluorescence exhibited an upward inflection during controlled increases in leaf-disc temperature. During exposure to 1008 &mgr;mol photons m-2 s-1 in an N2 atmosphere, 21 &mgr;L L-1 isoprene had no effect on the thermally induced inflection of steady-state fluorescence. The maximum quantum efficiency of photosystem II photochemistry decreased sharply as leaf-disc temperature was increased; however, this decrease was unaffected by exposure of leaf discs to 21 &mgr;L L-1 isoprene. Therefore, there were no discernible effects of isoprene on the occurrence of symptoms of high-temperature damage to thylakoid membranes. Our data do not support the hypothesis that isoprene enhances leaf thermotolerance.

Journal Article↗
PubMed1990

Transient gene expression in maize, rice, and wheat cells using an airgun apparatus.

An airgun apparatus has been constructed for transient gene expression studies of monocots. This device utilizes compressed air from a commercial airgun to propel macroprojectile and DNA-coated tungsten particles. The beta-glucuronidase (GUS) reporter gene was used to monitor transient expression in three distinct cell types of maize (Zea mays), rice (Oryza sativa), and wheat (Triticum aestivum). The highest level of GUS activity in cultured maize cells was observed when distance between stopping plate and target cells was adjusted to 4.3 centimeters. Efficiency of transformation was estimated to be 4.4 x 10(-3). In a partial vacuum of 700 millimeters Hg, velocity of macroprojectile was measured at 520 meters per second with a 6% reduction in velocity at atmospheric pressure. A polyethylene film placed in the breech before firing contributed to a 12% increase in muzzle velocity. A 700 millimeters Hg level of vacuum was necessary for maximum number of transfornants. GUS expression was also detected in wheat leaf base tissue of microdissected shoot apices. High levels of transient gene expression were also observed in hard, compact embryogenic callus of rice. These results show that the airgun apparatus is a convenient, safe, and low-cost device for rapid transient gene expression studies in cereals.

Journal Article↗
PubMed1990

Does water deficit stress promote ethylene synthesis by intact plants?

The effect of plant water deficit on ethylene production by intact plants was tested in three species, beans (Phaseolus vulgaris L.), cotton (Gossypium hirsutum L.) and miniature rose (Rosa hybrida L., cv Bluesette). Compressed air was passed through glass, plant-containing cuvettes, ethylene collected on chilled columns, and subsequently assayed by gas chromatography. The usual result was that low water potential did not promote ethylene production. When plants were subjected to cessation of irrigation, ethylene production decreased on a per plant or dry weight basis of calculation. No significant promotion of ethylene production above control levels was detected when water deficit-treated bean or cotton plants were rewatered. The one exception to this was for cotton subjected to a range of water deficits, plants subjected to deficits of -1.4 to -1.6 MPa exhibited a transient increase of ethylene production of 40 to 50% above control levels at 24 or 48 hours. Ethylene was collected from intact leaves while plants developed a water deficit stress of -2.9 megapascals after rewatering, and no significant promotion of ethylene production was detected. The shoots of fruited, flowering cotton plants produced less ethylene when subjected to cessation of irrigation. In contrast, the ability of bench drying of detached leaves to increase ethylene production several-fold was verified for both beans and cotton. The data indicate that detached leaves react differently to rapid drying than intact plants react to drying of the soil with regard to ethylene production. This result suggests the need for additional attention to ethylene as a complicating factor in experiments employing excised plant parts and the need to verify the relevance of shock stresses in model systems.

Journal Article↗
PubMed1991

The Alton Dean pressure infusor: an evaluation.

An automatically pressurised infusor system, the Alton Dean infusor, has been compared with two types (cloth and plastic) of commonly used pneumatically pressurised bags. All the infusors had reasonably accurate pressure gauges but pressure could only be consistently maintained with the cloth infusors or with the Alton Dean infusors when connected to a compressed air supply. Sequential fast infusions were possible with all infusors, but simultaneous infusions could be limited in number when the pressure infusor was connected directly to pipeline gas. One of the Alton Dean pressure infusors tested had a leak in the pressurisation system, and the pressure adjustment valves were difficult to manipulate. These may require modification.

Evaluation Studies as Topic↗
PubMed1997

Integrity, maintenance and caries susceptibility of sealed surfaces in adolescents receiving regular care from general dental practitioners in Scotland.

Pit and fissure sealants (sealants) are recognized as an effective caries preventive measure. The aim of this study was to assess the fate of occlusal surface sealants in a sample of 'regularly' attending adolescent patients (mean age 12.5 years at baseline) of 41 general dental practitioners, participating in a 3-year prospective clinical trial. A subsidiary aim was to compare the caries status of completely sealed surfaces with that of inadequately sealed surfaces over the same period. Baseline and three annual follow-up examinations were conducted by one trained and calibrated examiner under optimal conditions (dental chair, operating light, and compressed air). Sealed occlusal surfaces were evaluated for sealant type, sealant coverage, and caries status of the surface. Data for the initial and final year examinations were available for 402 subjects, who had 1377 sealants at baseline. Surfaces with optimal sealant coverage at baseline (n = 592) were significantly less likely to have become decayed (dentinal caries) or to have been restored by year 4 than surfaces with less than complete coverage (P < 0.001). Considering sealant maintenance during the study, 484 of the sealants were of optimal coverage (covered the fissure system) at the final examination. However, only 135 surfaces demonstrated evidence of maintenance by attaining optimal coverage. It is concluded that the fissure sealants in this sample may not have received the regular maintenance required to ensure full surface coverage and thus provide maximal caries protection, as inadequately sealed surfaces were more likely to decay than completely sealed surfaces.

Adolescent↗
PubMed1980

The ejector flowmeter as air/oxygen mixing device. An apparatus providing gas mixtures with adjustable oxygen content for high-flow humidification systems.

The ejector flowmeter is constructed for continuous removal of excess gas from anaesthetic circuits. This instrument can be used as an air/oxygen mixing device for high-flow humidification systems in wards where compressed air is not available. Pure oxygen is used as driving gas through the ejector. A nomogram has been constructed to show the relationship between oxygen driving pressure, inlet of air to the flowmeter, FIO2 and total outflow.

Air↗
PubMed1995

Home mechanical ventilation in the aftermath of the Hanshin-Awaji earthquake disaster.

Children who were dependent upon home mechanical ventilation (HMV), suffered in various ways from the disastrous Hanshin-Awaji earthquake disaster. The earthquake abruptly cut the supplies of water, gas and electricity, causing intense anxiety for those families. Through loss of the respirator function, some of them experienced an unexpected catastrophe. In the disaster area, there were children who were dependent upon HMV (19 cases) and children who were preparing for HMV in hospitals (nine cases). Information was gathered from questionnaires about the disaster, communication and correspondence with families. None of the 28 cases died or were injured. Nineteen cases had a variety of problems. In eight cases, respiratory support problems were acute. Nevertheless, all of them survived the crisis successfully even in the midst of such a catastrophic situation. An organization of HMV children's families, called the Baku-Baku Club, helped families with HMV problems by supplying water, food, oxygen and compressed air cylinders among other things. Additional outside batteries for portable respirators are essential equipment for HMV, especially for emergencies. A manual for clarifying the system for support in the Baku-Baku Club and a registration system for public medical service should be established in preparation for such a crisis.

Child↗
PubMed2006

Extraction of features from ultrasound acoustic emissions: a tool to assess the hydraulic vulnerability of Norway spruce trunkwood?

The aim of this study was to assess the hydraulic vulnerability of Norway spruce (Picea abies) trunkwood by extraction of selected features of acoustic emissions (AEs) detected during dehydration of standard size samples. The hydraulic method was used as the reference method to assess the hydraulic vulnerability of trunkwood of different cambial ages. Vulnerability curves were constructed by plotting the percentage loss of conductivity vs an overpressure of compressed air. Differences in hydraulic vulnerability were very pronounced between juvenile and mature wood samples; therefore, useful AE features, such as peak amplitude, duration and relative energy, could be filtered out. The AE rates of signals clustered by amplitude and duration ranges and the AE energies differed greatly between juvenile and mature wood at identical relative water losses. Vulnerability curves could be constructed by relating the cumulated amount of relative AE energy to the relative loss of water and to xylem tension. AE testing in combination with feature extraction offers a readily automated and easy to use alternative to the hydraulic method.

Botany↗
PubMed1975

Evaluation of isobaric oxygenation for the aged with cognitive impairment: pilot study.

The effect of isobaric oxygenation on psychogeriatric subjects, with mild cognitive impairment was assessed in a single-blind controlled pilot study. Three of the 7 subjects were treated with a mixture of 97% oxygen plus 3% carbon dioxide, and 4 treated with compressed air. The oxygen or air was administered during two 1.5 hr sessions daily for fifteen consecutive days. Use of a miner's type mask ensured a closed system which permits the maximal partial pressure of oxygen. Psychologic and clinical observations did not indicate any advantage for the oxygenation therapy. Minimal side effects, which arose only in the oxygen group, may have involved some interactions between CO2 sensitivity and anxiety. Careful differential diagnosis and the control of motivational factors are of major importance in any study of the effects of oxygenation upon symptoms in psychogeriatric patients.

Aged↗
PubMed1998

Gas exchange and lung mechanics during percutaneous transtracheal ventilation in an unparalyzed canine model.

OBJECTIVE: To compare the efficacy of percutaneous transtracheal ventilation (PTV) in the unparalyzed state with that in the paralyzed state using a sedated nonobstructed canine model. METHODS: Eight mongrel dogs (16.8-32 kg) were anesthetized, instrumented, and placed in a volume plethysmograph. Anesthesia was achieved with pentobarbital sodium (up to 30 mg/kg). The spontaneous respiratory drive was kept intact. PTV was performed using a 13-ga transtracheal catheter and compressed air at 45 psi at an I:E ratio of 1:3 (15 breaths/min). Each dog was sequentially ventilated in both the paralyzed and unparalyzed states. The paralyzed/unparalyzed sequence was alternated among the animals to avoid sequence bias. Paralysis was achieved with succinylcholine (0.1 mg/kg bolus and 0.01 mg/kg/min drip). Reversal of paralysis was achieved by discontinuing the succinylcholine infusion. Key variables, including arterial blood gas, tidal volume, and pulmonary mechanics, were measured and compared for the paralyzed and unparalyzed states. RESULTS: Gas exchanges and lung mechanics were similar between the unparalyzed and paralyzed states. There was no significant difference in mean pH, pCO2, pO2, tidal volume, or peak inspiratory transpulmonary pressure. There was also no significant difference in pulmonary resistance or pulmonary compliance. CONCLUSION: In a sedated nonobstructed canine model, PTV is as efficacious in the unparalyzed state as it is in the paralyzed state. The lung mechanics are also similar in the 2 states. These data suggest that it may be unnecessary to induce paralysis when using PTV for emergency ventilation in the heavily sedated state.

Animals↗
PubMed1980

Assessment of tooth mobility using small loads. I. Technical devices and calculations of tooth mobility in periodontal health and disease.

An apparatus for recording tooth mobility of maxillary anterior teeth using loads below 100 p in a bucco-lingual direction is described. Strain gauges and a differential transformer are used as sensors of force and displacement. The displacement is recorded at the same location on the tooth surface and in the same direction as the loading force. Compressed air is used as the source of force. Documentation of signals is obtained by means of a two-channel potentiometric recorder. Tooth mobility was studied in six subjects with healthy periodontal conditions and in six subjects with moderate periodontal disease. Repeated measurements under standardized conditions demonstrated a satisfactory reproducibility of the measuring method. Tooth mobility curves within the 20-80 p loading range were transformed to lines of regression. Analysis of such lines seems to provide further information of tooth mobility qualities as compared to previous methods of tooth mobility measurements.

Dental Stress Analysis↗
PubMed1983

Effect of IRM on human dental pulp.

IRM has been shown to be superior to conventional ZnOE cements. This study is a biotechnical investigation of IRM's effect on the dental pulp with respect to its sealing capacity. Enamel-dentin test bodies with IRM fillings were used in the in vitro part, where insufficiencies in sealing were detected with compressed air. The in vivo part included 44 buccal cavities in intact premolars. In teeth in which the material effect of IRM was tested, the IRM fillings were sealed off from the saliva by acid etch and composite resin. The observation intervals were 1, 7 and 28 days. Histologic changes such as capillary dilatations and presence of inflammatory cells in the pulp adjacent to the dentinal tubules involved in the cavity preparation were registered. The in vitro test showed no leakage in five cases out of six. After extreme temperature cycling, the leakage was comparable with that of zinc-containing amalgam of traditional alloy. The pulpal changes were mild and mainly ascribed to the material effect of IRM, since no evidence was found of leakage of biologic importance.

Dental Bonding↗
PubMed1995

Implications, prevention and management of subcutaneous emphysema during endodontic treatment.

Subcutaneous emphysema (SCE) is a possible complication of both nonsurgical and surgical endodontic treatment. A review of the literature pertinent to endodontic intervention and SCE is highlighted, while the causes of and recommendations for the prevention of SCE are provided. A review of the pathways whereby compressed air may travel through potential spaces in the head and neck is also illustrated in an attempt to identify the possibility of morbidity and even mortality should operator induced SCE occur in a patient.

Humans↗
PubMed2006

Exercise is the primary factor associated with Hsp70 induction in muscle of treadmill running rats.

AIM: The cytoprotective, inducible stress protein, Hsp70, increases in muscles of rodents subjected to strenuous treadmill running. Most treadmill running protocols employ negative reinforcement to encourage animals to exercise. As these stimuli may themselves activate stress responses, the present investigation was conducted to determine their contribution to the exercise-induced expression of Hsp70. METHODS: Twenty-one male Sprague-Dawley rats were randomly divided into three equal groups including an exercise group (EX), which ran on a treadmill at 30 m min(-1) for 60 min; a stimulation group (STIM), which was not allowed to run, but was stimulated with compressed air and mild electric shock concurrently with their exercising cohort; and a control group (CON), which was housed in the treadmill room during the exercise period. Animals were killed 24 h post-experiment and hearts (H), soleii (SOL) and white gastrocnemii (WG) were harvested and analysed for Hsp70 content (mean% +/- SEM of standard). RESULTS: Significant increases in Hsp70 (as a % of standard) were noted in H and WG (H = 77.4 +/- 8.5; WG = 93.9 +/- 18.4) of EX but not in STIM (H = 32.5 +/- 4.6; WG = 32.0 +/- 3.4) or CON (H = 20.5 +/- 3.7; WG = 32.4 +/- 7.4). In SOL, Hsp70 expression in EX (126.7 +/- 6.2) was different from STIM (98.3 +/- 10.9) only. This occurred, despite the fact that all groups were exposed to a stressful environment and exhibited elevated (P < 0.001) temperatures (EX -41.2 +/- 0.1 degrees C > STIM -40.5 +/- 0.2 degrees C > CON -39.0 +/- 0.1 degrees C) indicative of a general stress response. CONCLUSIONS: These data suggest that exercise per se, rather than environmental conditions or noxious stimuli, are responsible for the induction of Hsp70 in rat muscle during treadmill running.

Animals↗
PubMed2002

Start-up behavior of viscoelastic fluid flow near a capillary entry.

The effect of elasticity on the capillary entry flow development process was investigated by applying a laser doppler velocimeter (LDV) and flow visualization. The fluid filling the test section was kept at rest under a pressure of compressed air or a natural head and then a valve below the capillary was quickly opened to start the flow. Although the development of the capillary entry flow field of a Newtonian fluid is virtually quasi-steady, it takes a considerable time for a viscoelastic PAA-solution to attain its terminal regime. The transient behavior of the flow rate of the PAA-solution is attributed to the gradual development process of the flow field upstream from the entry.

Capillary Action↗
PubMed2003

Natural gas cleanup by means of membranes.

This paper deals with the use of membranes for hydrocarbon dewpointing and dehydration of natural gas. Based on experience gained from membrane applications in separating organic vapors from off-gas and process streams, as well as the dehydration of compressed air, membranes have been developed and tested for use in high pressure applications. Membranes and membrane modules have been modified to withstand the high operating pressure. Calculation programs were developed to understand the separation performance and to provide the necessary information for optimizing membrane design. A real challenge was the introduction of the vacuum mode dehydration operation in order to achieve the highest possible dewpoint reduction with minimum methane loss.

Journal Article↗