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Biomedical subjects

J Dai

Publications and source records attributed to J Dai.

At least 109 records · Page 6Linked to original sources
PubMed1999

Extraction and colorimetric determination of azadirachtin-related limonoids in neem seed kernel.

A colorimetric method was developed for the determination of total azadirachtin-related limonoids (AZRL) in neem seed kernel extracts. The method employed acidified vanillin solution in methanol for the colorization of the standard azadirachtin or neem seed kernel extracts in dichloromethane. Through the investigation of various factors influencing the sensitivity of detection, such as the concentration of vanillin, acid, and the time required for the formation of color, optimum conditions were selected to perform the assay. Under the optimum conditions, a good linearity was found between the absorbance at 577 nm and the concentration of standard azadirachtin solution in the range of 0.01-0.10 mg/mL. In addition, different extraction procedures were evaluated using the vanillin assay. The HPLC analysis of the extracts indicated that if the extractions were performed in methanol followed by partitioning in dichloromethane, approximately 50% of the value determined by the vanillin assay represents azadirachtin content.

Colorimetry↗
PubMed1999

Growth induction of hepatic stimulator substance in hepatocytes through its regulation on EGF receptors.

The cytosolic liver-specific growth factor-hepatic stimulator substance (HSS) has been shown to be able to amplify the rat hepatocyte proliferation responded to EGF. In order to get more insight into the mechanism, the regulatory effect of HSS on EGF-receptor (EGF-R) and the receptor phosphorylation at molecular level was studied. HSS partially purified from weanling rat liver was given to cultured hepatocytes and its influence on EGF-R specific binding and internalization as well as mRNA expression were investigated. The results showed that preincubation of hepatocytes with HSS could lead to an increase in [125I]-EGF binding to its receptors and inhibit EGF-induced receptor down-regulation. Furthermore, the over-expression of EGF-R mRNA stimulated by HSS was seen during 2-12 h after the incubation. Additionally, it was demonstrated with human hepatoma SMMC-7721 cells in Western blot that the EGF-R expression and the receptor autophosphorylation were increased with dose/time-dependency after HSS treatment. These results strongly suggest that the mechanism of HSS action on hepatocyte growth might be related to its modulation on EGF-R and receptor-mediated signaling transduction.

Animals↗
PubMed1999

Retrovirus-mediated herpes simplex virus thymidine kinase gene therapy approach for hepatocellular carcinoma.

The therapeutic effect of herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) system on hepatocellular carcinoma was studied in this experiment. The tk-containing retroviral recombinants were used to infect hepatoma cells (BEL-7402) and the cells were treated with ganciclovir (0-1000 microg/ml). The results showed that HSV-tk gene could be efficiently transferred in vitro into hepatoma cells and stably expressed. The growth potential of the tk-containing cells was significantly inhibited by GCV (P<0.01) as compared to the non-tk-containing cells. The antitumor effect of HSV-tk/GCV system was also produced ex vivo in tk-containing tumor of nude mice as characterized by a marked decrease in tumor growth after GCV treatment contrary to a progressive enlargement of non-tk-containing tumors. Although the histological examination demonstrated that the efficiency of the gene transfer was less than 30%, the killing effect of HSV-tk/GCV system on hepatocellular carcinoma was still significantly generated. The proper mechanism of HSV-tk gene therapy on hepatic tumor referred as "bystander effect" in therapeutic approach has not been found in this study and required to be explored further.

Animals↗
PubMed1999

ACE inhibitors in HF restore canine pulmonary endothelial function and ANG II vasoconstriction.

Chronic mitral regurgitation (MR) in dogs results in pulmonary congestion and increased cardiac angiotensin-converting enzyme (ACE) activity and angiotensin (ANG) II levels. ACE could contribute to altered pulmonary vasomotion in heart failure, and ACE inhibitor (ACEI) therapy may normalize pulmonary vasomotion. We evaluated pulmonary artery (PA) responses to ANG II and bradykinin (BK) in control dogs, in dogs with 4 mo of MR, in MR dogs treated with the ACEI ramipril (MR + R), and in control dogs treated with ramipril (C + R). Mean PA systolic pressure increased in MR dogs (21 +/- 4 mmHg) but was normal in MR + R dogs (13 +/- 1 mmHg). Constriction of PA rings to ANG II was depressed in MR dogs. ACEI treatment (MR + R) restored ANG II responsiveness, but peak ANG II response (3.6 +/- 0.2 g) in MR + R dogs remained lower than in C + R dogs (4.7 +/- 0.2 g). Endothelium-dependent relaxation to BK was decreased (-87 +/- 4% C, -65 +/- 4% MR; P < 0.05). Ramipril (MR + R) restored relaxation to BK. This demonstrates that pulmonary congestion results in impaired pulmonary vasomotion to ANG II and BK, which ACEIs could normalize, supporting the use of ACEIs in clinical management of chronic congestive heart failure.

Angiotensin II↗
PubMed1999

Induction of fibrogenic mediators by fine and ultrafine titanium dioxide in rat tracheal explants.

Respirable ambient particles [particulate matter <10 micrometer (PM(10))] are associated with both acute and chronic adverse health effects including chronic airflow obstruction. PM(10) can induce expression of inflammatory and fibrogenic mediators, but there is controversy about the types and/or sizes of particles involved and, in particular, whether ultrafine particles are the major toxic agents. To examine whether particle size affects mediator generation, we exposed rat tracheal explants, an inflammatory cell-free model of the airway wall, to various concentrations up to 500 microgram/cm(2) of fine (0.12 micrometer) or ultrafine (0.021 micrometer) titanium dioxide (anatase), maintained the explants in an organ culture in air for 1-7 days, and used RT-PCR to examine the expression of fibrogenic mediators and procollagen. No increase in gene expression was seen at 1 or 3 days, but at 5 days, ultrafine dust induced a small increase in procollagen. At 7 days, fine titanium dioxide produced significantly greater increases for platelet-derived growth factor (PDGF)-B, transforming growth factor-alpha, and transforming growth factor-beta compared with those by ultrafine dust; both dusts produced similar increases for PDGF-A; and ultrafine dust produced increases in procollagen expression, whereas fine dust had no effect. Expression levels were dose related. Both dusts produced a similar decrease in expression of PDGF receptor-alpha and a similar increase in PDGF receptor-beta. These observations suggest that ultrafine particles are intrinsically able to induce procollagen expression even in the absence of inflammatory cells; that chronic exposure to PM(10) may result in chronic airflow obstruction, in part because of ultrafine particle-mediated increases in airway wall fibrosis; and that chemically identical dusts of differing size can produce quite different patterns of gene expression in the airway wall. Differential upregulation of PDGF receptors does not appear to explain dust-induced fibrosis in this model.

Air Pollutants↗
PubMed1999

Measurement of four tumor marker antigens in the sera of pregnant women.

We sought to determine the maternal serum levels of four tumor-associated antigens during the three trimesters of pregnancy in healthy women. CEA, CA 228, CA 15-3, and Her2/neu oncogene product p105 assay values were determined for 90 healthy pregnant women during the three trimesters of pregnancy at five participating evaluation sites. Results were compared to means and cut-off values determined for healthy nonpregnant women. Differences in assay values in the 1st and 3rd trimester were analyzed for statistical significance (Student's t-test). CEA, CA 228 and CA 15-3 assay values in general were found to be within the normal range. CA 15-3 and Her2/neu p105 serum assay values were above the cut-off (3.3% and 8.2%, respectively) and were significantly elevated in the 3rd trimester as compared to the 1st trimester of pregnancy (P < 0.05 and P < 0.001, respectively). CEA and CA 228 may be of potential value in monitoring pregnant women with malignant disease. Normal elevations in 3rd trimester serum Her2/neu p105 and CA 15-3 assay values should be considered when monitoring a pregnant patient with malignant disease.

Adolescent↗
PubMed1999

Effects of cigarette smoke on nitric oxide synthase expression in the rat lung.

To examine the effects of cigarette smoke on nitric oxide synthase (NOS) gene expression and protein production, groups of rats were exposed to smoke once only or daily and were sacrificed after 1, 2, 7, or 28 days of exposure. NOS-1, NOS-2, and NOS-3 mRNAs in whole lung were quantified using reverse transcription polymerase chain reaction (RT-PCR), and NOS protein levels were determined by Western blots. Neither NOS-1 gene expression nor protein levels changed with smoke exposure. Levels of NOS-2 expression were more than doubled in smokers at Day 1 and decreased to control values during 1 month with daily smoke exposure, while protein levels did not change. NOS-3 expression was increased approximately 35% after 2 days of smoke exposure and remained increased to 28 days, whereas protein levels were increased by approximately 60% at Day 7 and remained elevated. In situ hybridization showed that NOS-2 was diffusely expressed in the lung parenchyma, airways, and vessels, and that NOS-3 was strongly expressed in vascular endothelium. Protein distribution, as determined by immunohistochemical staining, was identical to mRNA tissue distribution, and these distributions were not changed by smoke. We conclude that smoke exposure induces a rapid but transient increase in transcription of NOS-2, and a sustained increase in transcription and translation of NOS-3; up-regulation of NOS occurs within the anatomic compartment where these genes are normally expressed. These findings indicate that cigarette smoke can directly and rapidly affect NOS expression, and thus potentially affect the function of the pulmonary vasculature.

Animals↗
PubMed1999

Construction of a stable bioengineered strain of biotechmycin.

A stable bioengineered strain of Biotechmycin (Streptomyces spiramyceticus WSJ-1) was constructed by integrating the 4"-isovaleryltransferase gene (ist) through homologous recombination into the chromosome of spiramycin-producing strain S.spiramyceticus F21. In this construction, a Streptomyces/E.coli shuttle plasmid pKC1139 (AmR) was used as the vector and tsr gene was inserted as the marker for selection of homologous recombination. This constructed strain, S.spiramyceticus WSJ-1, was genetically very stable in production titer and in the production of biotechmycin as well as in carrying tsr selective marker when grown without pressure. The fermentation of S.spiramyceticus WSJ-1 was also improved compared with the original strain harboring unintegrated plasmid. Southern hybridization confirmed the integrated status of the ist gene in the host genome.

Acyltransferases↗
PubMed1999

A brief history of antibiotic science.

As the greatest achievement in the history of microbiology, the story of antibiotic is an extremely inspired chapter in its history. Like the developmental process of other sciences, antibiotic reveals a history of first accumulating experience, followed by the stage of interpretation of the phenomena as other experimental study. Meantime, there is no end to the discovery of new antibiotics. Currently, the scope and province of antibiotic research is expanding both in its profundity and coverage.

Anti-Bacterial Agents↗
PubMed1999

[Ultrasonic and CT diagnosis of large upper abdominal mass].

OBJECTIVE: To assess accuracy of ultrasonic (US) and CT diagnosis of big mass in the upper abdomen. METHODS: Data from 38 clinically and pathologically confirmed cases were retrospectively analyzed and accuracy of their preoperative US and CT diagnosis compared. RESULTS: US diagnosis was correct in 3 of 9 (33.3%) cases with a mass in the liver, in 16 of 21 (76.2%) cases with a mass in the adrenal gland and in 2 of 4 cases with a mass in the kidney. In contrast, CT diagnosis was correct in 2 of 9 (22.2%) cases with a mass in the liver, in 4 of 18 (22.2%) cases with a mass in the adrenal gland and none in a case with a mass in the kidney. In 4 cases with a mass in the spleen, neither US nor CT diagnosis was correct. CONCLUSION: Because organs in the upper abdomen are closely located with each other, correct imaging localization of big mass in this region is not without difficulty. In this series, accuracy of diagnosis with US and CT is comparable, but for localizing tumor in the adrenal gland, US imaging seems superior. US and CT are both incapable of accurately diagnosing large mass in the spleen.

Abdominal Neoplasms↗
PubMed1999

[CT findings of metastatic and primary neoplasms of the kidney: a comparative study].

OBJECTIVE: To study CT findings of renal metastases and compare them with primary renal cell carcinoma. METHODS: CT features of eleven cases of renal metastases and one hundred cases of primary renal cell carcinoma confirmed by histopathology were studied and compared. The metastastic tumors arised from lung carcinoma in 6 cases, esophagus carcinoma in 2 cases and one in each of adrenal cortical carcinoma, testis seminoma and unknown primary tumor. RESULTS: Renal metastases accounted for 3.7% of all malignant tumors of the kidney. The ratio of renal metastases to second primary renal carcinoma was 1:1. On CT, the renal metastases appeared as diffusely invasive, ill-definded mass (63.6%), 18.2% of the neoplasms were multiple, without or less exophytic (81.8%) and without or with minimal enhancing on postcontrast scan (100%). The tumor invaded the pelvocalyceal system (72.7%). In contrast, the primary renal cell carcinomas were nodular, rounded or lobulated and more exophytic mass with well-defined border and regular contours (87.0%). Moderate to high enhancing postcontrast (80.7%) was observed with obvious necrosis (60.2%), foci of calcification (15.0%) and invasion of the renal vein and inferior vena cava (7.0%). CONCLUSION: Contrast-enhanced CT is helpful in the differential diagnosis of renal metastases from primary renal cell carcinoma. But for those showing single, more exophytic mass with well-defined border and intense enhancing postcontrast, the correct diagnosis depends on histopathology.

Adult↗
PubMed1999

[The clinical features of myocardial infarction in patients younger than 35 years and over 45 years of age].

OBJECTIVE: To investigate the clinical features and the characteristics of coronary angiography in young patients with myocardial infarction. METHODS: 27 patients younger than 35 years with myocardial infarction were studied with respect to their history, habit of smoking and drinking and body weight index. Comparison was made between the left ventricular ejection fraction with ultrasound method and X-ray heart/chest ratio in patients with or without thrombolytic therapy. Selective coronary angiography was performed in 23 of the 27 patients. RESULTS: All of the 27 patients were male. 81.5% of them had smoking index more than 100, 55.5% drinking index more than 150, 51.9% family history of hypertension and 72.2% low blood level of HDL cholesterol. Most of the cardiac accidents took place in the night and morning. 17.4% of the patients had angiographically normal coronary arteries and 30.0% mild stenosis (no significant stenosis). 39.1%, 8.7% and 4.4% of the patients had one-vessel, two-vessel and three- vessel disease respectively. The frequency of patients with left ventricular ejection fraction less than 0.5 was 6.0% in patients with thrombolytic therapy and 33.3% without. CONCLUSION: 47.8% of the patients younger than 35 years with myocardial infarction has no or no significant stenosis of the coronary arteries. Heavy smoking is the most important one of relative factors for young patients with myocardial infarction. Other factors include low blood level of HDL cholesterol, drinking index of more than 150 and family history of hypertension in order. Thrombolysis treatment helps to maintain ventricular performance.

Adult↗
PubMed1999

[Clinical practice of spherical allogeneic biological membranous implant in the eye socket].

OBJECTIVE: To investigate the effect of implantation of spherical allogeneic biological material implant after eyeball enucleation. METHODS: A spherical allogeneic biological material implant was implanted in the eye socket after eyeball enucleation in 50 cases including stage I in 48 cases and stage II in 2 cases. RESULTS: After operation, the motility of installed artificial eyes was good in 49 cases, the orbit and eyelids were full in all the cases. In the follow-up of 4 - 24 months (mean, 8 months), the conjunctival wound and muscular tissue were adherent firmly to the biological material, and there were no postoperative infection, no dislocation and shift of the implant. CONCLUSION: The spherical allogeneic biological membranous implant is an ideal material for the implantation in the eye socket after enucleation.

Adolescent↗
PubMed1999

[Histopathology studies on 8,673 cases of ocular adnexal hyperplastic lesions and tumors].

OBJECTIVE: To study the histopathologic classification of ocular adnexal hyperplastic lesions and tumors according to the histogenesis and the anatomic sites. METHOD: To analyze retrospectively the pathologic specimens of 8,673 cases of ocular adnexal hyperplastic lesions and tumors between 1961 - 1997. RESULTS: There were 7,265 benign cases (83.77%), and 1,408 malignant cases (16.23%). Classification by anatomic sites: eye lid 5,313 cases (61.26%), orbit 1,484 cases (17.11%) and epibulbar 1,876 cases (21.63%). Classification by histogenesis: (1) Primary tumor 6,679 cases: epitheliogenic 2,481 cases (37.15%), mesenchymal 753 cases (11.27%), lympho-hematopoietic 102 cases (1.53%), neurogenic 1,542 cases (23.09%), congenital abnormal embryogenetic 1,767 cases (26.46%), uncertain resource tumor 34 cases (0.50%). (2) Secondary tumor 13 cases; (3) Metastatic tumor 9 cases; (4) Non-tumor lesion 1,972 cases. CONCLUSION: The classification is helpful to the histopathologic diagnosis and the study about the detailed distribution of common ocular adnexal hyperplastic lesions and rare tumors, and it also increases the pathologic diagnostic data in North China.

Eyelid Neoplasms↗
PubMed1999

[Inhibitory effects of recombinant human neurotrophin-4/5 protein on neurotoxicity caused by arsenic trioxide].

OBJECTIVE: To study preliminarily the inhibitory effects of recombinant human neurotrophin (hNT)-4/5 protein on neurotoxicity caused by arsenic trioxide (As(2)O(3)). METHODS: Nerve cells of the chicken embryonic forebrain and PC12 cells were co-cultured with recombinant hNT-4/5 protein and As(2)O(3) (0 - 16 micromol/L) for 24 and 48 hours, respectively, to observe the survival of nerve cells and the outgrowth of PC12 cells, with clone expression and recombination techniques. RESULTS: There was significant difference in survival rate of nerve cells between the experimental and control groups (P < 0.01) after co-culture for 48 hours, and survival rate and number of neuron outgrowth increased with the concentration of hNT-4/5 protein. CONCLUSION: Recombinant hNT-4/5 protein could inhibit neurotoxicity caused by As(2)O(3), which provided a basis to find an anti-toxic factor in the environment by genetic engineering.

Animals↗
PubMed1999

[Rapid determination of saccharin sodium in ice cream by high performance liquid chromatography (HPLC)].

This is a method for the rapid determination of saccharin sodium in ice cream by HPLC. A radial compression C18 cohumn, 100 mm x 8 mm i.d., and ultraviolet detector at 220 nm were applied to the determination without extraction. The solution of samples would be determined after they were treated with the solution of copper sulfate and sodium hydroxide in water. The detectable amount was 0.38 mg/kg, the coefficient of variation CV was 1.72%, and the recovery was 96.25%-101.75%.

Chromatography, High Pressure Liquid↗
PubMed1999

[Intensity-modulation radiotherapy using independent collimator: algorithm study].

To investigate algorithms for independent collimator (IC) to modulate beam intensity distributions. Field-setting sequences were determined for three clinical intensity distributions with two forward algorithms. The delivery order of all fields in the sequences was optimized in order to minimize the overall jaw-moving time. Suppose treatments were performed with Varian 600C, delivery time was calculated. The delivery time was between 5 min to 10 min, It was approximately inversely proportional to machine dose rate, and also related to algorithm, number of intensity levels and metrix element size.

Algorithms↗