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Biomedical subjects

J S Pan

Publications and source records attributed to J S Pan.

At least 19 recordsLinked to original sources
PubMed2006

Nucleation and growth of cobalt nanostructures on highly oriented pyrolytic graphite.

Cobalt in the form of three-dimensional (3D) hemispherical clusters (size approximately 10-30 nm) were observed to grow on pristine graphite surfaces via a Volmer-Weber growth mode. X-Ray photoelectron spectroscopy (XPS) reveals that these clusters are physisorbed on the surface. In the presence of minute surface contamination, the morphology of Co changes into a mixture of irregular and hemispherical three-dimensional islands. The formation of irregular islands appears to be mediated by the chemical interactions between Co and the surface contaminants as evidenced from analysis of the carbon pi-pi* transitions. Further analysis of size distribution of Co nanoclusters grown on pristine surfaces shows a critical nucleus size of i* = 1, i.e. a Co dimer forms the smallest stable cluster on a pristine graphite surface.

Adsorption↗
PubMed2005

The molecular mechanism of actinomycin D in preventing neointimal formation in rat carotid arteries after balloon injury.

The pathological mechanism of restenosis is primarily attributed to excessive proliferation of vascular smooth muscle cells (SMC). Actinomycin D has been regarded as a potential candidate to prevent balloon injury-induced neointimal formation. To explore its molecular mechanism in regulating cell proliferation, we first showed that actinomycin D markedly reduced the SMC proliferation via the inhibition of BrdU incorporation at 80 nM. This was further supported by the G1-phase arrest using a flowcytometric analysis. Actinomycin D was extremely potent with an inhibitory concentration IC50 at 0.4 nM, whereas the lethal dose LD50 was at 260 microM. In an in vivo study, the pluronic gel containing 80 nM and 80 microM actinomycin D was applied topically to surround the rat carotid adventitia; the thickness of neointima was substantially reduced (45 and 55%, respectively). The protein expression levels of proliferating cell nuclear antigen (PCNA), focal adhesion kinase (FAK), and Raf were all suppressed by actinomycin D. Extracellular signal-regulated kinases (Erk) involved in cell-cycle arrest were found to increase by actinomycin D. These observations provide a detailed mechanism of actinomycin D in preventing cell proliferation thus as a potential intervention for restenosis.

Animals↗
PubMed2000

[Production of herbicide-resistant rice with transforming heterogene].

Using pAHC20 (containing Bar gene), pWRG1515 (containing GUS gene and hygromycin phosphotransferase gene), and pCAMBIA3300 RG with Bar gene and snowdrop lectin (GNA) gene as donor DNA, the micro-adventitious shoots and the calli induced from mature embryos of Oryza sativa 87203, Eyi105, Shangnong aromatic glutinous rice as recipients were transformed with particle bombardment and Agrobacterium tumefaciens strain LBA4404 containing pAL4404, respectively. After chosen with phosphinothricin and antibiotic, GUS detection and PCR analysis, The results showed that the foreign genes had been transformed microprojectile-mediated to Oryza sativa Eyi105, the regeneration plants were obtained, and, 5 transgenic calli of Oryza sativa Eyi105 were obtained with Agrobacterium-mediated transformation.

Genes, Plant↗
PubMed1996

Protein crystal growth in microgravity using a liquid/liquid diffusion method.

Crystallization of proteins by liquid liquid diffusion method was performed in microgravity using the MDA Minilab aboard the US Space Shuttle. Three proteins, namely lysozyme, trichosanthin, and a new lechin, were crystallized in the space experiment. In contrast to the results of space experiments with a tube-like vapor diffusion method, the crystallization conditions for growing better crystals in space are remarkably different from the conditions optimized on earth. This may be due to difficulties in ground optimization, which are caused by gravity-dependent phenomena, in particular the specific convective flow occurring with liquid liquid diffusion.

Biotechnology↗
PubMed1993

In vitro studies on the effects of dehydroepiandrosterone and corticosterone on hepatic steroid receptor binding and mitochondrial respiration.

1. The in vitro effects of dehydroepiandrosterone (DHEA), DHEA-sulfate (DHEA-S) and related steroids on glucocorticoid corticosterone (GC) binding in hepatic cytosol and hepatic mitochondrial respiration were examined in male BHE/cdb and Sprague-Dawley (SD) rats. 2. The Kd and the IC50 for GC binding in SD rats were 5- and 2-fold higher, respectively, than in BHE/cdb rats. 3. Hepatic cytosol from BHE/cdb rats bound six times more [3H]-GC to receptors than that from SD rats. 4. The percentage displacement and Bmax of GC for its receptors were similar for the two strains of rats. 5. DHEA and DHEA-S did not displace GC from its receptors. 6. DHEA and related non-sulfated steroids decreased state 3 mitochondrial respiration, respiratory control and oxidative phosphorylation capacity in a dose-dependent manner with malate + pyruvate as substrate.

Animals↗
PubMed1993

Glucose turnover in lean and obese rats of the SHR/N-cp and LA/N-cp strains.

1. The relationship between hypertension, obesity, non-insulin-dependent diabetes mellitus and various parameters of glucose metabolism was studied. Lean and obese rats of the SHR/N-cp and LA/N-cp congenic strains were studied at four months of age. 2. Tritium and 14C-labeled glucoses were infused in one set of rats while tritiated water and 14C-labeled alanine were infused in a second group. 3. Glucose oxidation, turnover, conversion to glycogen, fatty acid synthesis, and alanine conversion to glucose were determined, as were blood pressure, pulse pressure and heart rate. 4. The presence of obesity influenced body weight, body fat, de novo fatty acid synthesis, organ weights, glucose mass, glucose oxidation, glucose synthesis, glucose carbon turnover and pulse pressure. 5. It had no effect on glycogen synthesis, tissue glycogen levels, blood glucose, glucose space, or blood pressure. 6. Strain differences were observed in final body weight, organ weights, blood pressure, pulse pressure, hepatic fatty acid synthesis, glucose mass, glucose space, glucose synthesis, liver glycogen levels and glucose conversion to muscle glycogen. 7. Strain-phenotype interaction effects were observed on glucose incorporation into hepatic glycogen, Cori cycle activity, hepatic de novo fatty acid synthesis, final body weight, fat pad weight, heart weight, and mean arterial pressure. 8. These results suggest that although obesity and hypertension are genetic traits in these rats, these traits are independent in their influence on the metabolism of glucose and the development of non-insulin-dependent diabetes mellitus.

Animals↗
PubMed1992

A novel cereal storage protein: molecular genetics of the 19 kDa globulin of rice.

A lambda gt11 cDNA library, constructed from poly(A)+ RNA isolated from immature rice seed endosperm, was screened with affinity-purified antibodies against the rice storage protein called alpha-globulin (previously), or the 19 kDa globulin (our term). A positive clone was isolated and sequenced and shown to encode a 21 kDa precursor for the 19 kDa globulin, based on the identity of portions of the inferred amino acid sequence and the sequence of three cyanogen bromide peptides of the 19 kDa globulin. Analysis of genomic DNA by Southern blotting using the cDNA clone probe revealed one hybridizing band in Eco RI, Hind III, and Bam HI digests. This strongly suggests that the 19 kDa globulin is encoded by a single-copy gene. Because of its single-copy nature and its abundance of Arg and lack of Lys, the 19 kDa rice globulin appears to be a particularly attractive target for genetically engineering increased Lys content in rice seeds.

Amino Acid Sequence↗
PubMed1991

Dietary fat saturation affects glucose metabolism without affecting insulin receptor number and affinity in adipocytes from BHE rats.

The effects of dietary fat source on epididymal fat cell insulin receptor binding and affinity and on glucose transport and use by genetically diabetic rats were studied. Male BHE rats were fed 6% fat/64% sucrose diets. The fat consisted of 1% corn oil plus 5% beef tallow, menhaden oil or corn oil. Glucose tolerance was assessed at 100, 300 and 600 d of age. At 100 d of age the fat pads were excised, isolated adipocytes prepared and insulin receptor number, receptor affinity, 3-O-methyl glucose uptake and glucose use determined. Insulin receptor number and binding affinity were not affected by dietary fat type. The transport and subsequent use of glucose were greater in fat cells from rats fed beef tallow compared with those from rats fed corn oil or menhaden oil. All three groups exhibited a deterioration in glucose tolerance with age. Although we observed greater glucose transport, oxidation and conversion to fatty acids in beef tallow-fed rats, we saw no differences in these measurements between cells from corn or menhaden oil-fed rats. Thus, we conclude that the effects of these dietary lipids are attributable to effects of saturated fatty acids on intracellular events rather than on the insulin receptor per se, and that the type of unsaturated fatty acid [(n-3) vs. (n-6)] is of little importance to the regulation of glucose metabolism by isolated adipocytes.

Adipose Tissue↗
PubMed1991

Dietary fat saturation affects hepatocyte insulin binding and glucose metabolism in BHE rats.

The influence of feeding 6% hydrogenated coconut oil, corn oil or menhaden oil on hepatocyte insulin binding, receptor number and glucose use was studied. Hepatocytes isolated from rats fed menhaden oil had a significantly greater affinity for insulin than hepatocytes from rats fed hydrogenated coconut oil. Glucose use was not influenced by diet; uniformly labeled glucose was metabolized to CO2 or to lipid similarly in cells isolated from rats fed the three oils. Thus, dietary fat type in a low fat diet influenced events at the plasma membrane without influencing intracellular events.

Adenosine Triphosphate↗
PubMed1991

[Diagnosis and treatment of rapidly progressive glomerulonephritis. An analysis of 20 cases].

In order to know the incidence and character of rapidly progressive glomerulonephritis (RPGN) in China, 20 patients with RPGN were analysed and 10 of them followed. Their diagnosis were confirmed by biopsy showing extensive crescent formation. Five patients were rebiopsied. RPGN was found in about 3% of the patients with glomerulonephritis in our center. Only one case was mediated by anti-GBM antibody, while the other 19 by immune complex. Prodromal infection was common (12/20). Hematuria, nephrotic syndrome and hypertension were found in 20, 15 and 12 patients respectively. Five patients without special treatment died of renal cause within 6 months. Intensive treatment (pulse methylprednisone or plasmapheresis) was effective in all of the four cases with cellular crescents. After the treatment, their renal function improved with decrease of proliferation and crescent formation as shown by rebiopsy. However, deterioration of renal function reappeared after 3 months to 3 years in three of the cases. It is shown that in China, RPGN was predominantly mediated by immune complex and is associated with a high incidence of prodromal infection. Clinically, nephrotic syndrome was more frequently seen here than in western countries. For improvement of the prognosis, it is necessary to pay attention not only to earlier diagnosis but also to protection of renal function after intensive therapy.

Acute Disease↗
PubMed1990

Thyroxine effects on parameters of glucose turnover in BHE rats fed menhaden oil.

The effect of hyperthyroidism on glucose turnover in BHE rats fed menhaden oil was studied. Thyroxine-treated rats had a greater glucose mass, a greater absolute glucose synthesis rate, less hepatic and muscle glycogen levels, and greater hepatic and peripheral fat cell lipogenic rates than nontreated rats. No differences in body weight gain were observed, nor were there differences in blood glucose levels, glucose space, or fractional reversible or irreversible glucose use. These observations suggest that thyroxine and menhaden oil were additive in their effects on glucose metabolism in BHE rats, which are genetically programmed to develop non-insulin-dependent diabetes mellitus.

Journal Article↗
PubMed1990

[Renal involvement in amyloidosis: analysis of 14 cases].

UNLABELLED: 14 cases were investigated between 1963 to 1988. Age ranging from 25-66 (mean 48.2). 9 cases (64%) were over age 50. Diagnosis was established by renal biopsy or autopsy. 11 cases (79%) were primary. 3 cases (21%) were secondary with chronic infection. Besides renal involvement, primary amyloidosis principally affected the heart, gastrointestinal tract and tongue. Hepatosplenomegaly and anemia were found in secondary cases. Proteinuria was found in 14 cases. Nephrotic Syndrome (NS) found in 8 cases, both renal insufficiency and hypertension were 21% respectively. In 3 cases performed renal venography, 2 cases showed renal vein thrombosis. 9 cases (64%) showed kidneys were enlarged. Congo red test showed positive reaction were 100% in secondary and 50% in primary. By light microscopy stained with congo red there was a specific protein deposited in glomeruli and mesangium, by electron microscopy. There was fine amyloid fibrils. These findings are characteristic and to have diagnostic value. CONCLUSION: (1) Renal amyloidosis is not very rare in China. (2) Proteinuria and NS were major clinical manifestations. (3) Renal biopsy and autopsy have diagnostic value, congo red test does not prove the absence of primary amyloidosis.

Adult↗
PubMed1990

Glucose turnover in BHE rats fed EFA deficient hydrogenated coconut oil.

The effects of feeding corn or hydrogenated coconut oil on various parameters of glucose metabolism in prediabetic BHE rats was studied. Weanling rats were fed a 6% fat-64% sucrose diet. At seven weeks of age, the rats were weight matched within diet treatments. Half of the rats were injected with 6(3)H/U14C glucose while their weight matched counterparts were injected with U14C alanine and 3HOH. Diet had no effect on glucose mass, glucose space, hepatic glycogen or blood glucose levels. However, diet did affect other parameters. HCO fed rats had higher fractional irreversible glucose turnover rates, fractional glucose carbon recycling, hepatic fatty acid synthesis rates, adipose fatty acid synthesis rate, lower muscle glycogen and lower rates of incorporation of glucose into muscle glycogen than corn oil fed rats. These differences in glucose flux explain the maintenance of glucose homeostasis in these prediabetic coconut oil fed rats in the face of increased fatty acid and glucose synthesis.

Animals↗
PubMed1989

Inhibition of implantation of murine bladder tumor by thiotepa in cauterized bladder.

This study was designed to determine the role of immediate intravesical instillation of single dose thiotepa post transurethral resection of bladder tumor in the prevention of recurrence by tumor implantation, using murine bladder tumor line 2 and 201 C3H/He mice. Previous studies have suggested implantation may take place as early as the first hour and reach its maximum in 24 hours after resection of bladder tumor. An in vitro dose response curve of MBT2 to thiotepa was established by treatment with various concentrations of thiotepa of 0.00, 0.01, 0.21, 0.44, and 1.91 mg./ml. In a group of 201 mice, the bladder was catheterized with a 24G angiocatheter, and a fine copper wire was inserted through the lumen. The bladder was cauterized by touching the wire with a Bovie coagulator for four seconds at the lowest setting. All bladders were instilled with 1 x 10(6) cells of murine bladder tumor line 2, followed by instillation of 1.91 mg./ml. of thiotepa with various time delays per treatment group. The bladder implantation rates were 30.4% (17/56), 3.4% (2/59), 6.5% (2/31) and 26.9% (7/26) in the control, immediate, one-hour delay and 24-hour delay groups, respectively. The urethral implantation rates were 21.4% (12/56), 0% (0/59), 6.5% (2/31) and 0% (2/26), respectively. The overall implantation rates (bladder, urethra, or both) were 42.9% (24/56), 3.4% (2/59), 6.5% (2/31) and 25.9% (7/27), respectively. Implantation rates were significantly higher in the control and 24-hour delay groups than in the immediate and one-hour instillation groups (p less than 0.05, Fisher Exact Test). We conclude from this animal model that intravesical instillation of single dose thiotepa, to be effective, should be initiated within the first hour after tumor resection, since it dramatically decreased the incidence of bladder and urethral implantation.

Administration, Intravesical↗
PubMed1989

[CT diagnosis of coal workers' pneumoconiosis].

In order to evaluate the usefulness of CT in CWP, 100 coal workers were examined with both chest radiograph and CT scan. Comparison was done, the result indicated that both modalities yielded similar sensitivity to simple CWP. The CT score of simple CWP correlated well with ILO classification and 1986 Chinese criteria for staging of pneumoconiosis, whereas in complicated CWP, the CT scan was significantly superior to chest radiograph. CT scan identified readily large opacities. It could detect large opacities in 40% of simple CWP diagnosed on the basis of chest radiograph. CT scan also identified more cavities and calcifications within large opacities. The CT attenuation values were less reliable. The authors were of the opinion that at present CT attenuation values is not recommended for routine evaluation of CWP.

Adult↗
PubMed1989

[Renal vein thrombosis in nephrotic syndrome--a prospective study of 54 cases].

Recent advance of radiographic technique makes antemortem diagnosis of renal vein thrombosis (RVT) possible. However the incidence of RVT in patients with nephrotic syndrome(NS) is still not known. This study was designed to investigate the incidence, clinical presentation and radiological features of RVT in NS patients in China. A prospective study including clinical, and pathological examination as well as renal venogram was carried out in all our hospitalized NS patients except those having contradiction for renal venogram. RVT was found in 23 of the 54 cases (42%) and there was obstruction in 34 renal vein branches. RVT was more common in left (19) than right side (15), in upper (19) than middle and lower branches (10). It is interesting that in our group not only membranous but also minimal change as well as mesangium proliferative glomerulonephritis had high incidence of RVT (47%, 45% and 36% respectively) Only 6 cases (26%) had a typical acute presentation with severe loin pain, significant increase of urinary protein, enlargement of involved kidney. Occasionally fever, deterioration of renal function and sterile urinary white cells were also present. The remaining patients (74%) had latent onset of RVT which could hardly be identified in the clinical course of the underlying NS. For the high incidence and atypical clinical course of RVT shown in our study, it is recommended that due attention should be paid of this complication during management of NS and interpretation of therapeutic response.

Adolescent↗
PubMed1986

Age and thyroid hormone as factors in the responses of BHE rats to starvation-refeeding.

The interacting effects of thyroid hormone, age, and duration of starvation on the enzyme and liver lipid responses of BHE rats to starvation-refeeding were studied. Rats were starved for 2, 4, or 7 days and refed a 65% glucose diet for 2 days. The rats were either 150 or 420 days of age and injected daily with either saline or 10 micrograms thyroxine/100 g body weight. Neither age nor duration of starvation affected the glucose-6-phosphate dehydrogenase or malic enzyme activity or liver lipid response to starvation-refeeding. However, thyroxine treatment potentiated the response to starvation-refeeding in the 420-day-old rats when the duration of starvation increased from 2 to 7 days.

Age Factors↗