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Biomedical subjects

X Q Sun

Publications and source records attributed to X Q Sun.

13 recordsLinked to original sources
PubMed2001

Effect of repeated +Gz exposures on energy metabolism and some ion contents in brain tissues of rats.

BACKGROUND: It has been demonstrated that during +Gz exposure cerebral blood flow is significantly reduced, resulting in brain ischemia. In pilots, such conditions could recur several times during centrifuge training and combat maneuvers and could possibly cause reversible change in brain energy metabolism. HYPOTHESIS: In rats there is an association between +10 Gz exposure and the decreased brain metabolism, as indicated by decreased adenosine triphosphate (ATP) and ATPase activity, and increased adenosine diphosphate (ADP) and lactate, etc. The aim of the present study was to examine the time course and recovery of brain energy metabolism, lactate, ATPase activity, Na+, K+, Ca2+ and water contents after three +10 Gz exposures in rats. METHODS: There were 64 male Sprague-Dawley rats that were restrained and placed on an animal centrifuge. They were divided into groups of 16. Control rats were exposed to +1 Gz and experimental rats were exposed to +10 Gz three times each for 3 min at 30-min intervals. After being euthanized, rat brains were removed 0 h, 1 h, or 6 h after the last centrifuge run. Brain samples were analyzed for energy metabolism, lactate, Na+-K+-ATPase activity, water and electrolytes contents. RESULTS: The cortical ATP content, Na+-K+-ATPase and lactate dehydrogenase (LDH) activities decreased significantly, whereas the cortical ADP, adenosine monophosphate (AMP) and lactate contents increased significantly 0 h after three +10 Gz exposures, as compared with those of control. The ATP, ADP, and AMP contents returned to their control levels 1 h after the +10 Gz exposures, however, lactate content, Na+-K+-ATPase and LDH activities delayed recovery 6 h after +10 Gz exposures. The cortical K+ content increased significantly 0 h and 1 h after +10 Gz exposures, and returned to the control level 6 h after +Gz exposures. Na+ and water contents increased significantly 1 h and 6 h after the +10 Gz exposures. There was no significant change in Ca2+ content after +Gz exposures. CONCLUSIONS: Three +10 Gz (3 min each) exposures were associated with transient depression of brain metabolism as indicated by a decrease in ATP, Na+-K+-ATPase activity, and an accumulation of lactate, and disturbance of ion homeostasis. It is suggested that a causal relationship might exist between repeated high +Gz exposures and brain metabolism.

Acceleration↗
PubMed1998

A vibrating trachea.

A case of relapsing polychondritis presenting as tracheomalacia is reported in which an unusual low pitched sound was heard at the mouth and over the chest wall during expiration. The sound was associated with expiratory airflow limitation and oscillation on the flow trace of approximately 50 Hz. Spectral analysis of the sound showed it to have the characteristics of sounds produced by flutter in flow limited flexible tubes. These observations suggest that the sound was produced by airflow induced flutter in the trachea and main airways and is further evidence in support of the dynamic flutter theory of wheeze production.

Airway Obstruction↗
PubMed1998

Inverse filtering applied to upper airway sounds.

Inverse filtering is a digital signal processing technique which may be applied to speech-like sounds to remove resonances introduced by upper airway cavities to leave a residual signal which is, in principle, spectrally flat and strongly related to the excitation source. The filter parameters, normally computed by a form of linear prediction analysis, are indicative of the frequencies and bandwidths of the resonances. This paper briefly outlines the principle of inverse filtering and describes two applications in the study of upper airway sounds for diagnostic purposes. The first application is concerned with the non-invasive measurement of variations in upper airway dimensions which occur with changes in posture. Results show that differences in the resonance frequencies caused by changes in posture can be measured, these being of the order of about 10% in normals. The measurement of such changes is known to be useful in the assessment of patients with sleep apnoea. The second application concerns the evaluation of vocal tract abnormalities resulting from infection in the larynx. Parameters derived from the residual are believed to be indicative of the existence and severity of a hoarse voice. Results have been obtained which support this theory.

Acute Disease↗
PubMed1998

Estimation of analogue pre-filtering characteristics for CORSA standardisation.

This paper is concerned with devising a standard procedure for determining the gain and phase responses of the analogue filters used to pre-process pulmonary signals prior to their digitisation. The customary high-pass filtering, in particular, will strongly affect the time-domain wave-shapes of digitised signals and this must be taken into account when analysing the signals. Several means of determining the effect of the high-pass filtering are investigated and a measurement procedure is proposed which may be easily carried out using simple laboratory equipment.

Humans↗
PubMed1994

[Argon laser photocoagulation for traumatic goniocyclodialysis].

8 cases of ocular hypotony due to traumatic goniocyclodialysis were successfully treated by argonlaser photocoagulation with few complications during a follow-up of 6-68 months. The authors emphasized early application of the therapy as an effective and safe procedure to recover almost normal anatomic and physiologic structures of the chamber angle.

Adolescent↗
PubMed1993

[Argon green laser photocoagulation for solitary choroidal hemangioma].

Eight (8) cases of solitary choroidal hemangioma associated with macular serous retinal detachment were treated with Argon green laser photocoagulation. The neoplasms were essentially eliminated and the retinas reattached. The visual acuity was improved unless the hemangioma involved the foveal region. No relapse occurred during a follow-up of 6 to 32 months. The laser parameters adopted were: spot size 300-400 microns, exposure 0.2-1.0 sec, and output 0.3-0.5 W.

Adult↗
PubMed1992

Estimation of respiratory mechanics in dogs with acute lung injury.

In mechanically ventilated anesthetized dogs with acute lung injury induced by intravenous infusion of oleic acid (OA), changes in airflow, lung volume, and tracheal (Pao), transpulmonary (Ptp) pressures were measured. Changes in lung mechanics were studied before and after OA infusion at intervals, during an observation period lasting 4-5 hours, by using the interrupter technique and identification technique, and by measuring the pressure-volume (PV) characteristics. The main results are listed as follows: (1) compliance and FRC showed a marked decrease, Pao and Ptp showed a marked increase within 2 hours after OA. (2) airflow resistance estimated by the identification technique showed a marked increase after OA. (3) static PV characteristics of both the lungs and total respiratory system showed similar changes 4 hours after OA, characterized by the presence of an inflexion on the inflation limb, increased hysteresis and a rightward and downward shift of the loop. (4) the trend of changes of dynamic PV characteristics obtained by changing the PEEP value in a stepwise manner, with the ventilation uninterrupted, was similar to that of the static PV curve. It is suggested that an on-line identification technique with one-compartment model to track the slow changes in combination with serial measurements of the dynamic PV characteristics of the total respiratory system would be more appropriate for monitoring lung mechanics of ventilated patients with ARDS.

Animals↗
PubMed1992

[Comparative analysis of amino acids of metacercaria and larvae of diploid and triploid of Paragonimus westermani].

The diploid type of Paragonimus westermani in Heilongjiang Province and triploid type of P. westermani in Liaoning Province were examined for amino acids by high performance liquid chromatography (HPLC). Eleven kinds of amino-acids of diploid type and 15 kinds of triploid type were found in metacercaria; 15 kinds amino acids of diploid type and 16 kinds of triploid type were detected in larvae. The amino acids were more abundant in larvae than in metacercaria and more in the triploid than in the diploid type. The predominant amino acids were cystine and glutamic acid.

Amino Acids↗
PubMed1991

[Analysis of 52 cases of retinal vein occlusion treated with laser photocoagulation].

41 of 52 cases of retinal vein occlusion (RVO) treated with laser photocoagulation were followed up for 3-30 months. Visual prognosis was good for patients of branch RVO, while visual improvement was not much for central RVO; however, the treatment could prevent or combat neovascularization and in turn neovascular glaucoma. Laser photocoagulation therapy of RVO was effective and few complications occurred if performed at an opportune time with an optimal wavelength or combination of wavelengths, and periodical follow-up and fluorescein angiography were useful in promoting the rate of successful operations.

Adult↗
PubMed1989

[Treatment of macular choroidal neovascular membrane with krypton red laser photocoagulation].

Ten (10) cases of macular choroidal neovascular membrane were treated successfully with krypton red laser (KRL) photocoagulation. The patients were followed up 3-15 months with no recurrence. Choroidal neovascular membranes outside the foveal region carried good visual prognosis, while poor visual outcome accompanied foveal involvement. The authors were encouraged by the efficacy of KRL photocoagulation in the treatment of macular choroidal neovascular membranes. Complications were few; however, the laser parameters, especially the output power, were key points to success.

Adult↗