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Biomedical subjects

W Li

Publications and source records attributed to W Li.

At least 1,153 records · Page 64Linked to original sources
PubMed1994

Agonist-induced phosphatidylinositide breakdown and mitogenesis in retinal capillary pericytes.

We have examined the effects of a variety of vasoactive agents and growth factors on phosphatidylinositide turnover and DNA synthesis in cultured retinal capillary pericytes. A complex correlation between phosphatidylinositide turnover and DNA synthesis varied with different agonists. The resulting data indicate that phosphatidylinositide turnover is not the sole signaling pathway, and there must be multiple signaling pathways involved in pericyte mitogenesis.

Animals↗
PubMed1994

Interaction between phosphoinositide-phospholipase C and phosphatidylcholine-phospholipase D in plasma membranes of retinal capillary pericytes.

The existence of phosphatidylcholine-specific phospholipase D (PC-PLD) was demonstrated in the isolated plasma membranes of retinal capillary pericytes. We determined PC-PLD activity, taking advantage of the transphosphatidylation activity of PC-PLD in the presence of ethanol, with phosphatidylethanol (PEt) formation. In the membrane environment, both phosphoinositide-specific phospholipase C (PI-PLC) and PC-PLD were activated by GTP gamma S. Neomycin, an inhibitor of PI-PLC, at a concentration (500 microM) capable of inhibiting 90% of the PI-PLC activity, only slightly inhibited the basal level of PC-PLD, but significantly decreased the GTP gamma S-activated PC-PLD by 66%. These findings indicate that the inhibitory effects of neomycin on PC hydrolysis may exert through the regulatory mechanisms of G proteins. Exogenous phosphatidic acid, a product of PC-PLD, stimulated, whereas PC, the substrate of PC-PLD, inhibited PI-PLC. These data implicate one mechanism by which PC-PLD may modulate PI-PLC activity through changing the phospholipid composition in the membrane, specifically the ratio of PA/PC. These findings are useful for the further studies on the communication between membrane-associated PI-PLC- and PC-PLD-mediated signal transduction pathways.

Animals↗
PubMed1994

Mirror symmetry and parallelism: two opposite rules for the identity transform in space perception and their unified treatment by the Great Circle Model.

Two opposite rules control the contributions of individual lines to the perceptual processing of two different spatial dimensions of egocentric localization and orientation. For lines restricted to the frontal plane, a tilted line on one side of the median plane induces a rotation of the orientation visually perceived as vertical (VPV) identical to that induced by the same tilt on the other side of the median plane, but the influences exerted on the elevation of visually perceived eye level (VPEL) are mirror symmetric. The rule for VPV fits our intuitions; the rule for VPEL does not. However, the reverse peculiarity holds when the inducing lines are rotated within sagittal planes (pitched): Two parallel, pitched-from-vertical lines on opposite sides of the median plane generate identical effects on VPEL but mirror symmetric effects on VPV. These counterintuitive symmetry reversals are reconciled by the Great Circle Model of spatial orientation (GCM), in which line orientations are represented by the great circle coordinates of their images on a sphere centered at the nodal point of the eye via central projection.

Humans↗
PubMed1994

The temporal bone in multiple myeloma.

Multiple myeloma is a malignant disease of the skeleton. Anatomically, any bone may ultimately come to be involved in a given case. In a literature review, no published series of temporal bone findings have been reported. In this study, oto-histopathologic changes associated with multiple myeloma are analyzed and reported in 15 temporal bones from 8 patients. The bone marrow of 13 temporal bones was involved by the tumor. Osteolysis was evident in 11 temporal bones. Serous otitis media (SOM) or purulent otitis media (POM) was seen in 13 ears with 12 showing mastoid effusions. Eight ears exhibited pathological changes in inner ears, including degeneration of the organ of Corti, atrophy of stria vascularis, decreased ganglion cells, and labyrinthine hydrops. The inner ear changes were most severe in 2 patients who had otologic symptoms. Infiltration of myeloma cells was not apparent in the middle ear mucosa or the inner ears.

Aged↗
PubMed1994

Toxicity of mildly modified low-density lipoproteins to cultured retinal capillary endothelial cells and pericytes.

To investigate the role of modified low-density lipoproteins (LDL) in the pathogenesis of diabetic retinopathy, we studied the cytotoxicity of normal and mildly modified human LDL to bovine retinal capillary endothelial cells and pericytes in vitro. Pooled LDL was incubated (in phosphate-buffered saline-EDTA, 3 days, 37 degrees C) under 1) nitrogen with additional chelating agents and 2) air, to prepare normal and minimally oxidized LDL, respectively. Similar conditions, but with the addition of 50 mM D-glucose, were used to prepare glycated and glycoxidized LDL. None of the LDL preparations was recognized by the macrophage scavenger receptor, confirming limited modification. Retinal capillary endothelial cells and pericytes were grown to confluence and then exposed for 2 or 3 days to serum-free medium (1% albumin) supplemented with normal or modified LDL (100 mg/l) or to serum-free medium alone. Cytotoxicity was assessed by cell counting (live and total cells) and by cell protein determination. Compared with normal LDL, modified LDL were cytotoxic to both cell types at both time points, causing highly significant decreases in live and total cell counts (P < 0.001) (analysis of variance). Reductions in cell protein also were significant for pericytes at day 3 (P = 0.016) and of borderline significance for endothelial cells at day 2 (P = 0.05) and day 3 (P = 0.063). Cytotoxicity increased as follows: normal < glycated < or = minimally oxidized < glycoxidized LDL. We conclude that, in diabetes, mild modification of LDL resulting from separate or combined processes of glycation and oxidation may contribute to chronic retinal capillary injury and thus to the development of diabetic retinopathy.

Analysis of Variance↗
PubMed1994

Human resources development and poverty alleviation: a study of 23 poor counties in China.

"In recent years, poverty has become a serious issue in the socioeconomic development of China. One of the most important features of poverty is 'poor population quality', a factor that also causes poverty. Human resources development (HRD) strategies have been used as a weapon against poverty in many developing countries; some have proven to be quite effective. This article, which researches the relationship between HRD indicators and poverty status, finds that enhancement of education levels, improvement of health status, the gaining of skills and experience, increasing time away from home and choosing suitable occupations, all can contribute greatly to the reduction and alleviation of poverty."

Asia↗
PubMed1994

[Exploration on the association between the pattern of HBV markers and infection of HCV among population].

Sera from 193 cases with positive HBV markers in April 1993 were detected for infection of HCV to explore the association between the pattern of HBV markers and the infection of HCV among population. The result showed that 14 patterns were found: the pattern of positive HBsAg, HBeAb, HBcAb (43.01%) and the pattern of positive HBsAg, HBeAg, HBcAb (30.57%) were more often seen. The percentage of HCV infection among cases infected with HBV was 11.39%. The difference of the positive rate of anti-HCV among various patterns of HBV markers was significant (chi 2 = 24.48, P = 2.062 x 10(-5).

China↗
PubMed1994

[Cloning and sequencing of promoter and signal sequence coding regions from Bacillus subtilis].

Promoter and signal sequence coding regions from B. subtilis were cloned in E. coli using a bifunctional and signal sequence selection plasmid pGPB14 as a vector. The Sau3A digested chromosome DNA was ligated with BamHI digested pGPB14. The ligated mixture was used to transform E. coli C600. Ampicillin and erythromycin resistant clones were selected. Recombinant plasmids were isolated from double resistant transformants. Restriction analysis showed that inserts of various length had been cloned and these inserts rendered the E. coli cells resistant to different concentrations of ampicillin. The recombinant plasmids were transformed and showed the same secretion function in B. subtilis. The amount and localization of beta-lactamase were determined in transformed E. coli and B. subtilis. The results indicate that the beta-lactamase activities of E. coli mainly in periplasm while the enzyme produced by B. subtilis secreted extracellularly. 10 of the cloned fragments were sequenced by Sanger's dideoxy chain termination method. The sequencing data show that all fragments contain promoter, ribosome binding site and signal sequence coding region.

Amino Acid Sequence↗
PubMed1994

Primary carcinoid of the renal pelvis.

We report a case of a surgically resected carcinoid of the renal pelvis diagnosed as papillary transitional cell carcinoma by light microscopy. Immunocytochemistry studies identified three immunoreactive products: cytokeratin, S-100 protein, and neuron-specific enolase. Ultrastructurally, dense core granules were seen. The histogenesis of renal pelvis carcinoid has not been clarified. This is the first documented case of a renal pelvis carcinoid.

Adult↗
PubMed1994

[Effect of bee pollen on maternal nutrition and fetal growth].

Plant pollen collected by the honeybee is called bee pollen, which is a natural nutrient. We studied the effects of the bee pollen of Brassia campestres L. on maternal nutrition and fetal growth. Pregnant Sprague-Dawley rats at O-d were divided randomly into three groups. The control group (C) was fed with a diet. The other two groups (A) and (B) were fed with the diet plus bee pollen 20 g/kg.d-1 and 10 g/kg.d-1, respectively. All the dams in each group took a diet and drank water and libitm. Pollen-fed dams in both groups (A) and (B) had greater body weight and higher levels of haemoglobin, total protein, serum iron and albumin (P < 0.01, P < 0.05). Fetuses of pollen-fed dams had greater body weight (P < 0.01) and lower death rate (P < 0.005). No gross external, visceral and skeletal malformations were observed in the fetuses. These results suggested that bee pollen could improve maternal nutrition without affecting normal fetal development. It is a practical and effective nutrient during pregnancy.

Animal Nutritional Physiological Phenomena↗
PubMed1994

[Role of adenosine in weak electro-acupuncture-induced depression of nociceptive response of spinal dorsal horn neurons in rats].

In this study, extracellular recordings were made from wide dynamic range (WDR) neurons in lumbar segments of the spinal cord in rats transsected at the first lumbar segment. The nociceptive discharges of WDR neurons were depressed by weak electro-acupuncture applied to "Yanglingquan"-"Xuanzhong" points. The depression was blocked by i.v. administration of adenosine receptor antagonists, theophylline and caffeine. The observations indicate that depression of the nociceptive response of the WDR neurons induced by weak EA may be mediated by adenosine within the spinal cord.

Adenosine↗
PubMed1994

[The application radionuclide bone imaging in the treatment of hallux valgus].

Radionuclide bone imaging (RNBI) was performed by means of 99mTc-MDP on both 20 health subjects (40 feet) and 20 patients with hallux valgus (26 feet). The results showed that radioactivity intake were increased in second (or third) metatarsal of 26 feet of hallux valgus. The ratio of radioactivity of the lesion and contralateral normal site (D/N) had statistical difference (P < 0.01). Both the patient and normal groups RNBI is a highly sensitive study and valuable for the classification of diagnosis. It help for selection of surgical treatment, as to evaluate the results of the treatment.

Adolescent↗
PubMed1994

Expression and secretion of alpha-amylase and glucoamylase in Saccharomyces cerevisiae.

alpha-Amylase genes of Bacillus licheniformis and glucoamylase cDNA of Aspergillus niger were ligated to a E. coli-yeast shuttle vector. The resultant plasmid was used to transform Saccharomyces cerevisiae to construct starch-degrading yeast strain. The results of enzyme activity assay and enzyme property analysis show that alpha-amylase and glucoamylase genes have been expressed simultaneously in yeast under the control of promoters and terminators of yeast MF-alpha 1 factor and PGK genes and over 99% of enzyme activities were secreted to the medium. The engineered yeast strain hydrolyses 97% of the starch (10%) in the medium after 6 days. The recombinant plasmid exists stably in yeast.

Aspergillus niger↗
PubMed1994

[Carotid body tumor: diagnosis and surgical treatment].

Carotid body tumors are rarely encountered and can present a difficult surgical problem. During the period of June 1988 to November 1992, 8 patients were operated on for carotid body tumors at PLA General Hospital. Details of the surgery, morbidity and outcome of these patients are presented. Our experience suggests that: 1) The presence of a pulsatile neck mass located in the region of carotid triangle, vertically fixed and laterally mobile, should raise the suspicion of a carotid body tumor; 2) Color Doppler flow imaging has a role to play in the diagnosis of carotid body tumor; 3) DSA is very important for a number of reasons, especially for the use of concomitant embolization; 4) Management of these tumours is primarily surgical; 5) The decision whether to resect the carotid artery or not can only be made intra-operatively based on status of the patient and tumor, there might be 4 surgical options open to the operators.

Adult↗
PubMed1994

[Using ELISA to evaluate the serologic and epidemiologic effect following rabies vaccination].

After vaccinating the people bitten by animals against rabies, we have examined their serum antibodies by using ELISA. One year later, we sent a mail to everyone of them inquiring if he had contracted rabies. The response rate was 85%. The case fatality rate of the positive antibody group was 0.24% (1/415). The case fatality rate of the negative antibody group was 3.16 (3/95). It showed that there was significant difference in the case fatality rate of rabies between the two groups, (P = 0.022). The dead person of the positive antibody group was bitten on his cheek by a rabid dog. He had not cleaned his wound. He had received 6 injections of rabies vaccines. His incubation period was 28 days. The P/N of serum antibody on the 28th day was 3.27.

Adult↗