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Biomedical subjects

Z L Lu

Publications and source records attributed to Z L Lu.

12 recordsLinked to original sources
PubMed1992

Behavioral lifetime of human auditory sensory memory predicted by physiological measures.

Noninvasive magnetoencephalography makes it possible to identify the cortical area in the human brain whose activity reflects the decay of passive sensory storage of information about auditory stimuli (echoic memory). The lifetime for decay of the neuronal activation trace in primary auditory cortex was found to predict the psychophysically determined duration of memory for the loudness of a tone. Although memory for the loudness of a specific tone is lost, the remembered loudness decays toward the global mean of all of the loudnesses to which a subject is exposed in a series of trials.

Acoustic Stimulation↗
PubMed1990

Coated amperometric electrode arrays for multicomponent analysis.

This paper describes a sensor array of several amperometric electrodes, each coated with a different permselective film. Coatings with different transport properties, based on size (cellulose acetate), charge (Nafion, poly(vinylpyridine), poly(ester sulfonic acid], and polarity (phospholipid) are employed in connection with a four-electrode thin-layer flow detector. With equipotential operation, the array's response pattern of each analyte provides a unique characterization of the individual components. Multicomponent analysis is obtained by taking advantage of the partial selectivity of the individual sensors and using a pattern recognition (multiple linear regression) method. Additional information is obtained by recording the complete hydrodynamic voltammogram at the individual sensors. The merits of the new array are illustrated for the quantification of neurologically significant catechol compounds.

Electrodes↗
PubMed1990

Highly stable phospholipid/cholesterol electrode coatings for amperometric monitoring of hydrophobic substances in flowing streams.

Composite electrode coatings based on a mixture of phosphatidylcholine and cholesterol offer remarkable mechanical stability under vigorous hydrodynamic conditions. The greatly improved stability (over single-domain phospholipid layers) is attained without compromising the attractive permselective response of lipid electrodes. The enhanced stability is attributed to changes in the fluidity/packing associated with the presence of cholesterol. Due to its high stability, simplicity, and fast and permselective response, the coated electrode seems well-suited for flow measurements of hydrophobic compounds. Parameters affecting the film permeability and the amperometric response are explored in the presence of numerous solutes of biological and pharmaceutical significance. Prevention of surface fouling (in the presence of surfactants) and applicability to selective assays of urine samples are illustrated. Such controlled access to the surface, based on solute polarity, greatly enhances the power of electrochemical flow detectors.

Chemistry, Physical↗
PubMed1989

[Studies on antifertility effect of testosterone undecanoate in combination with danazol in male rats].

Male rats were injected i.m. with 12 mg/kg testosterone undecanoate (TU) twice in the first and once in each of the succeeding 2 months in combination with oral danazol (DZ) of 30 mg/kg/day. Antifertility effects were observed with morphological and functional techniques for half a year. Results showed: reduction of testis weight and seminiferous tubule diameter; decrease of sperm viability and motility in canada epididymidis; and lowering of testosterone levels in testis and phospholipid and protein contents in epididymis. 75 days after treatment spermatogenesis was arrested mainly in the secondary spermatocyte stage with a decrease in sperm count to 0 in the cauda epididymidis. Mating test showed 0% fertility. Testicular testosterone and epididymis phospholipid and protein contents were found to have dropped further. However, all of the above-mentioned changes recovered completely 100 days after cessation of treatment. The authors suggest that TU plus DZ in a suitable dose suppresses spermatogenesis, retards maturation and shortens the survival time of sperm in the epididymis by reducing testosterone levels in the testis.

Animals↗
PubMed1989

[Ectopic ACTH syndrome caused by bronchial carcinoid].

A 35-year male patient with clinical and biochemical manifestations of severe hypercorticism was thought to have Cushing's syndrome of pituitary origin. However, the surgically removed pituitary adenoma was not confirmed by pathological examination. There was no improvement after transsphenoidal microsurgery Chest CT scan showed a small mass located at the upper-lobe of the right lung. This tumor (1.8 x 1.0 x 1.0 cm) was removed and one course of radiotherapy with linear accelerator was given. Remission was achieved clinically and biochemically after these therapies. The diagnosis of bronchial carcinoid was confirmed by pathological findings. Metastasis of a lymph node was also proved. The tumor cells was found to contain ACTH and related peptides with radioimmunoassay, immunocytochemistry and electron microscopy. Gel filtration of the tumor extracts showed molecular heterogeniety of ACTH related peptides and that the big-form were in large percentage.

ACTH Syndrome, Ectopic↗
PubMed1989

[Experimental studies on the role of retinal lipid peroxidation induced by intraocular iron foreign body].

Experimental studies were made to evaluate the role of lipid peroxidation in retinal damage by intraocular iron foreign bodies. It was found that after iron particles were implanted into the vitreous bodies (1) iron concentration in the aqueous humour rose rapidly and significantly (n = 24, P less than 0.01), (2) malondialdehyde (MDA) a degradation metabolite of lipid peroxidation, in the retinas increased significantly (n = 24, P less than 0.05), and (3) superoxide dismutase (SOD) activity decreased (n = 11, P less than 0.05). These findings suggest that lipid peroxidation plays a key role in the retinal damage of siderosis bulbi, and provide a solid basis in studying the pathogenesis and guiding clinical management of the disease.

Animals↗
PubMed1989

[Evaluation of various parameters in the differential diagnosis of Cushing's disease and Cushing's syndrome caused by adrenal adenoma].

Evaluation of the clinical and biochemical parameters for differential diagnosis of two types of Cushing's syndrome, pituitary-dependent Cushing's disease and adrenal adenoma, was studied with analysis of the histories of 79 cases of Cushing's disease and 23 cases of adrenal adenoma. The data show that the symptoms, signs and the routine biochemical analyses were not significantly different between two groups. High-dose dexamethasone suppression test had about 90% coincidence rate in the differential diagnosis with 24-hour urine free cortisol (UFC), which was better than 24-hour urine 17-OHCS. Interestingly, low-dose dexamethasone test was highly valuable and the 24-hour urine 17-KS quite helpful in the differential diagnosis of two types of Cushing's syndrome. Serum N-POMC measurement was the most valuable among the parameters, because there was no overlap between the two groups of Cushing's syndrome.

17-Ketosteroids↗